Letters
are needed to build and sustain excellence, innovation, and methodological rigor in peer review research. Mario Malički, MD, MA Erik von Elm, MD, MSc Ana Marušić, MD, PhD Author Affiliations: Department of Research in Biomedicine and Health, University of Split School of Medicine, Split, Croatia (Malički, Marušić); Institute for Social and Preventive Medicine, University Hospital Lausanne, Lausanne, Switzerland (von Elm). Corresponding Author: Ana Marušić, MD, PhD, Department of Research in Biomedicine and Health, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia ([email protected]). Author Contributions: Dr Marušić had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: von Elm, Marušić. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Drafting of the manuscript: all authors. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: Malički. Administrative, technical, and material support: Malički, Marušić. Study supervision: von Elm, Marušić. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Marušić and von Elm are members of the Advisory Board of the Seventh International Congress on Peer Review and Biomedical Publication. Previous Presentation: This study was presented at the Seventh International Congress on Peer Review and Biomedical Publication, Chicago, Illinois, September 8-10, 2013. Additional Contributions: We thank the Esteve Foundation for organizing a Discussion Group on Editorial Research in Barcelona (Catalonia, Spain) on December 12-13, 2012, which gave us the idea for the study. We thank Annette Flanagin, RN, MA, and Drummond Rennie, MD, at JAMA for providing access to the abstracts and JAMA articles from the early Peer Review Congresses, for which they were not compensated. 1. Rennie D. Preface. In: Peer Review in Scientific Publishing. Papers from the First International Congress on Peer Review and Biomedical Publication. Chicago, IL: Council of Biology Editors; 1991. 2. National Library of Medicine. Medical Subject Headings: “Peer Review, Research.” http://www.ncbi.nlm.nih.gov/mesh/?term=peer+review%2C+ research. Accessed October 5, 2013. 3. Bossuyt PM, Reitsma JB, Bruns DE, et al; Standards for Reporting of Diagnostic Accuracy. Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. Clin Chem. 2003;49(1):1-6. 4. Dickersin K, Scherer R, Lefebvre C. Identifying relevant studies for systematic reviews. BMJ. 1994;309(6964):1286-1291. 5. Dickersin K. The existence of publication bias and risk factors for its occurrence. JAMA. 1990;263(10):1385-1389. 6. Scherer RW, Langenberg P, von Elm E. Full publication of results initially presented in abstracts. Cochrane Database Syst Rev. 2007;(2):MR000005.
COMMENT & RESPONSE
Mortality in Patients With Hypovolemic Shock Treated With Colloids or Crystalloids To the Editor The Colloids vs Crystalloids for the Resuscitation of the Critically Ill (CRISTAL) trial1 found no difference in 28day mortality but improved 90-day mortality in patients in the intensive care unit (ICU) with hypovolemic shock resuscitated using colloids (mainly hydroxyethyl starch solutions) vs crystalloids (mainly isotonic saline). The CRISTAL trial was unblinded and allocation of patients occurred by envelope ran-
domization using fixed block size, which may not have ensured allocation concealment. That adequate randomization may have failed and allocation of patients into the 2 intervention groups may have been skewed in the CRISTAL trial is supported by marked baseline imbalance in the numbers of patients that received crystalloids and colloids in the 12 hours prior to randomization. In a large trial like CRISTAL, such differences are unlikely to occur by chance. Lack of allocation concealment and blinding can introduce bias, which often leads to overestimation of intervention effects.2 Bias is also suggested because the results of the CRISTAL trial contrast with those of other recent trials with low risk of bias3,4 and a systematic review5 that showed increased use of renal replacement therapy, increased mortality, or both, with hydroxyethyl starch. Interpretation of the CRISTAL trial1 is further complicated by the variety of colloid and crystalloid solutions used in the 2 intervention groups. In addition, randomization may not have been preserved in the subgroup analyses by type of fluid received because the allocation to different types of fluids may have depended on trial site in addition to randomization. Anders Perner, MD, PhD Nicolai Haase, MD, PhD Jørn Wetterslev, MD, PhD Author Affiliations: Intensive Care Medicine, Copenhagen University Hospital, Copenhagen, Denmark. Corresponding Author: Anders Perner, MD, PhD, Copenhagen University Hospital, Blegdamsvej 9, DK-2100 Copenhagen, Denmark (anders.perner @regionh.dk). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Perner reported receiving research grants from CSL Behring and Fresenius Kabi; and payment for lectures from LBP SA. Dr Haase reported being a member of the steering committee of the Scandinavian Starch for Severe Sepsis/Septic Shock (6S) Trial, a publicly funded trial with support by B Braun Medical, which provided study fluid free of charge. No other disclosures were reported. 1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Savović J, Jones HE, Altman DG, et al. Influence of reported study design characteristics on intervention effect estimates from randomized, controlled trials. Ann Intern Med. 2012;157(6):429-438. 3. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 4. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134. 5. Zarychanski R, Abou-Setta AM, Turgeon AF, et al; Association of hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients requiring volume resuscitation: a systematic review and meta-analysis. JAMA. 2013;309(7):678-688.
To the Editor The CRISTAL trial1 requires scrutiny because its results contradict other high-quality evidence.2 The CRISTAL trial was stopped for futility based on no difference in 28-day
jama.com
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
1067
Letters
mortality, but reported numerically lower mortality for the colloids group. However, eFigure 1 in the article suggests lower mortality in the crystalloids group when the trial was stopped. eFigure 2 shows a sudden increase in probability of death at 28 days in both groups; this indicates either censoring (suggesting the denominator for 90-day mortality was wrong) or an unexplained and puzzling cluster of deaths on day 28 resulting in the mortality difference at 90 days. Because the trial was open label, it is important to demonstrate equality of resuscitation between the 2 groups as occurred in previous crystalloid vs colloid trials.3,4 Annane and colleagues 1 reported blood pressure only during the first 24 hours, which may be influenced by many factors in the ICU, including use of sedation and vasopressors. Other data such as daily heart rate, filling pressures, and urine output for at least the period of active resuscitation should be provided. eFigure 4c indicates a marked increase in the cardiovascular Sequential Organ Failure Assessment (SOFA) score from day 0 to day 1 in the crystalloids group, an effect not apparent in the larger blinded trials.3,4 This suggests that unblinded clinicians may have treated the 2 groups unequally. Hydroxyethyl starch, the predominant colloid used, causes renal injury.4,5 eFigure 4b demonstrates an increase in the renal SOFA score from day 0 to day 1 in the colloids but not the crystalloids group. The SOFA score is derived from serum creatinine level and urine output with increasing creatinine being a more reliable marker of renal injury. Annane et al1 should provide daily creatinine levels by treatment assignment so that renal injury can be properly assessed. The explanations offered for the results of the CRISTAL trial differing from larger blinded trials (that the recommended dose of starch was not exceeded and that patients in the crystalloids group received chloride-rich fluids [normal saline]) do not stand up to scrutiny. Patients in the Crystalloid vs Hydroxyethyl Starch Trial (CHEST) received on average only 10% of the recommended daily maximum dose of starch,4 and normal saline was the comparator for both the CHEST and the Saline vs Albumin Fluid Evaluation (SAFE) studies.3,4 Rinaldo Bellomo, MD, FCICM Simon Finfer, MD, FCICM John Myburgh, PhD, FCICM Author Affiliations: Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Australia (Bellomo); George Institute for Global Health, University of Sydney, Sydney, Australia (Finfer, Myburgh). Corresponding Author: Simon Finfer, MD, FCICM, University of Sydney, PO Box M201 Missenden Road, Camperdown, Australia 2050 (sfinfer@georgeinstitute .org.au). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Bellomo reported receiving personal fees and nonfinancial support from Gambro; grants and personal fees from Baxtter; and personal fees from Philips. Dr Finfer reported receiving institutional grants and travel reimbursement from Fresenius Kabi; honoraria for speaking at symposia sponsored by PPTA, which were paid to the International Sepsis Forum. Dr Myburgh reported receiving institutional payments for serving as a board member for Baxter; and receiving grants, payment for lectures, and travel expenses from Fresenius Kabi. No other disclosures were reported.
1068
1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Perel P, Roberts I, Ker K. Colloids versus crystalloids for fluid resuscitation in critically ill patients. Cochrane Database Syst Rev. 2013;2:CD000567. 3. Finfer S, Bellomo R, Boyce N, French J, Myburgh J, Norton R; SAFE Study Investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. N Engl J Med. 2004;350(22):2247-2256. 4. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 5. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134.
To the Editor Dr Annane and colleagues1 reported that 28-day mortality (primary end point) did not significantly differ between patients with hypovolemic shock assigned to various colloid fluid therapies (69% of whom received hydroxyethyl starch) vs crystalloid fluid therapies. They also reported that 90-day mortality (one of many secondary end points) was significantly higher with crystalloids. Annane et al1 appropriately acknowledged that the 90day mortality results were exploratory. However, potential users of hydroxyethyl starch need clarity on the robustness of this finding and whether it is consistent with the published literature. Such clarity is particularly necessary given the recent decision by the European Medicines Agency allowing hydroxyethyl starch use in patients with hypovolemic shock and bleeding but not in patients with sepsis, burn, or critically illness. With regard to consistency, the results of this trial contradict 3 randomized controlled trials in patients with critically illness or sepsis in which renal morbidity or mortality was significantly higher with hydroxyethyl starch compared with crystalloid therapy.2-4 Notably, the CRISTAL trial1 is the only study to show a significant survival benefit for hydroxyethyl starch vs another resuscitation fluid. For a secondary end point to be convincing when the primary outcome is not significant, the P value should ideally remain robust after correcting for multiple comparisons. Because at least 7 secondary end points were examined, the authors should provide a P value for 90-day mortality corrected for multiple comparisons. In addition, the 90-day end point was added midway through the 9-year trial,5 further obscuring how to interpret the finding. The 90-day cumulative incidence curve shows increases in both treatment groups at 28 days, suggesting a brisk, unexplained accumulation of deaths at that point. Given that this end point in some patients was collected retrospectively, Annane et al1 should describe how the missing mortality data between days 28 and 90 were handled. The sequential triangular test figure shows a sharp decrease in the curve between the fifth and sixth interim analyses, and the authors should comment on this unusual pattern. In addition, in light of the recent European Medicines Agency decision, a test of interaction between survival difference at 90 days between the 2 fluid therapy groups
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
jama.com
Letters
and the presence vs absence of shock due to bleeding would be helpful to determine whether hydroxyethyl starch has a different effect on bleeding in patients with hypovolemic shock than it does in other critically ill patients. Christian Brun-Buisson, MD Junfeng Sun, PhD Charles Natanson, MD Author Affiliations: Service de Réanimation Médicale, GH Henri Mondor, Créteil, France (Brun-Buisson); Department of Critical Care Medicine, National Institutes of Health Clinical Center, Bethesda, Maryland (Sun, Natanson). Corresponding Author: Christian Brun-Buisson, MD, Service de Réanimation Médicale, GH Henri Mondor, 51 Ave de Lattre de Tassigny, 9010 Créteil, France ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Brun-Buisson reported receiving a grant from the European Commission. No other disclosures were reported. Disclaimer: The opinions expressed in this article are those of the authors and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the US government. 1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Brunkhorst FM, Engel C, Bloos F, et al; German Competence Network Sepsis (SepNet). Intensive insulin therapy and pentastarch resuscitation in severe sepsis. N Engl J Med. 2008;358(2):125-139. 3. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 4. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134. 5. ClinicalTrials.gov website. CRISTAL: colloids compared to crystalloids in fluid resuscitation of critically ill patients: a multinational randomised controlled trial. http://www.clinicaltrials.gov/ct2/show/NCT00318942. Accessed October 3, 2013.
In Reply Dr Perner and colleagues suggest that allocation concealment was not ensured in the CRISTAL trial. However, procedures were in place to hide the allocation sequence until assignment. Sequentially numbered, sealed, and opaque envelopes were used. An envelope assigned to a patient was opened only after the investigator wrote patient information on it. The signed inclusion sheet with patient and randomization details was faxed to the coordinating center, allowing monitoring of treatment allocation to unique patients in appropriate order. Only 6 errors in envelope assignment were found, corresponding to simultaneous inclusion of a patient by multiple investigators in the same center. This process ensured a low risk of bias.1 Perner and colleagues also suggest that the 2 groups were not balanced at baseline. However, imbalances in a randomized trial occur by chance. All of the baseline variables except for fluid administration prior to ICU admission were well balanced between the 2 groups. Dr Bellomo and colleagues suggest that physicians favored management of patients assigned to colloids vs crystal-
loids. In practice, the 2 treatment groups did not differ with regard to time to initiation of a vasopressor (mean [SD] of 0.8 [4.9] days for the colloids group vs 0.5 [1.9] days for the crystalloids group, P = .82), mechanical ventilation (mean [SD] of 0.4 [5.2] days for the colloids group vs 0.2 [2.2] days for the crystalloids group, P = .89), or renal replacement therapy (mean [SD] of 2.3 [1.5] days for the colloids group vs 2.2 [1.4] days for the crystalloids group, P = .71). Moreover, the study was designed to show a higher risk of death and kidney injury with colloids than with crystalloids, which was in keeping with the beliefs of the investigators throughout the recruitment period. Dr Brun-Buisson and colleagues and Bellomo and colleagues point out a brisk increase in the number of deaths at 28 days. We do not have a definite explanation for this accumulation of deaths, which occurred in both treatment groups. There were no missing data for 90-day mortality or errors in the denominator. Decision to withdraw care preceded death prior to 28 days in 11% of the patients treated with colloids and 13% of patients treated with crystalloids, and preceded death after 28 days in 9% of both groups. The decrease in the sequential triangular test figure between the fifth and sixth interim analyses is a pattern that has been observed previously.2 All 3 groups of writers incorrectly stated that the CRISTAL trial found results contradictory to trials that compared a starch solution with a single crystalloid.3-5 None of these trials3-5 or the CRISTAL trial found significant differences in 28-day mortality between crystalloids and colloids. The 90-day mortality outcome was secondary for the Efficacy of Volume Substitution and Insulin Therapy in Severe Sepsis (VISEP) trial and the CRISTAL trial. Only the Scandinavian Starch for Severe Sepsis/Septic Shock (6ES) trial showed a barely significant increase in 90day mortality with colloids (relative risk [RR], 1.17; 95% CI, 1.01-1.36).3 In the other 2 trials, death rates at 90 days were not different between groups.3,5 Thus, any mortality difference at 90 days between colloids and crystalloids remains uncertain. Our findings of fewer deaths at 90 days could only be considered exploratory because it was a secondary outcome. Correction for multiple analyses was not planned for the secondary outcomes. There was no heterogeneity in the treatment effect on mortality in nontraumatic hemorrhagic shock vs nonhemorrhagic shock (P = .10). The prevalence of renal replacement therapy was significantly increased with starch in the VISEP 3 and 6ES trials.4 In CHEST,5 this risk was not statistically significant (RR, 1.21; 95% CI, 1.00-1.45), fewer patients receiving starch than isotonic saline developed renal injury, and the proportion of patients who developed renal failure was not different. In the CRISTAL trial, there was no difference between treatment groups in creatinine levels over time up to 28 days. Thus, there was no marked difference in renal adverse events between CHEST and the CRISTAL trial, which are the 2 largest trials on fluid therapy. Djillali Annane, MD, PhD Sylvie Chevret, MD, PhD
jama.com
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
1069
Letters
3. Brunkhorst FM, Engel C, Bloos F, et al; German Competence Network Sepsis (SepNet). Intensive insulin therapy and pentastarch resuscitation in severe sepsis. N Engl J Med. 2008;358(2):125-139.
proliferative functional cardiomyocytes may offer an advantage because intermediate tumorigenic cells are not generated and the reprogrammed cells can mature in the in vivo environment.4 However, directly reprogrammed, terminally differentiated postmitotic cells provide only a limited supply of tissues for drug and toxicity screening. Instead, nonpluripotent, tissuespecific precursors could be generated, such as cardiomyocyte progenitors or oligodendrocyte progenitors.5 These expandable cells can generate clinically significant amounts of therapeutic cell types yet they limit the dangers and inefficiencies associated with generation of unwanted cell types from iPSCs. Direct reprogramming is a potentially more costeffective, efficient, and safer alternative approach to iPSCbased technology.
4. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911.
Rajesh C. Rao, MD Brian J. Dlouhy, MD
Author Affiliations: Raymond Poincaré Hospital, University of Versailles, Garches, France (Annane); Saint Louis Hospital, Paris, France (Chevret). Corresponding Author: Djillali Annane, MD, PhD, Raymond Poincaré Hospital, University of Versailles, 104 Blvd Raymond Poincaré, 92380 Garches, France ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. 1. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. http://www.cochrane-handbook.org. Accessibility verified February 11, 2014. 2. Hulot JS, Cucherat M, Charlesworth A, et al. Planning and monitoring of placebo-controlled survival trials: comparison of the triangular test with usual interim analyses methods. Br J Clin Pharmacol. 2003;55(3):299-306.
5. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134.
Stem Cells and Cardiovascular Drug Development To the Editor We are hopeful that induced pluripotent stem cells (iPSCs) will lead to powerful drug discovery platforms based on their ability to model disease at the cellular level and will serve as a reservoir of transplantable tissues for many diseases. Dr Mordwinkin and colleagues1 highlighted these aspects to assert that iPSC technology may reduce preclinical drug development times and more accurately predict efficacy and toxicity of novel or off-label therapeutic agents in human cardiomyocytes. However, iPSC-based technology is not the ideal platform for drug and toxicity screening or for the derivation of transplantable tissues. Currently, somatic cell reprogramming to iPSCs takes several weeks, in part because the process is laborious, with reprogramming efficiencies ranging from 0.005% to 0.01%.2 Although more efficient, directed human iPSC differentiation to terminally differentiated cell types in vitro requires several additional weeks or months. 2 Moreover, during many of the steps in direc ted iPSC differentiation, unwanted intermediate cell types with proliferative and tumorigenic properties are produced. 3 Therefore, iPSCbased technology remains expensive, time consuming, and in the context of therapeutic transplantation, potentially risky due to the possibility of iPSC-derived tumorigenic cells in the graft. For these reasons, safer and more cost-effective approaches to drug discovery, toxicity screening, and generation of therapeutically valuable cell types should use strategies that skip the iPSC stage altogether. Direct reprogramming (also known as lineage conversion or transdifferentiation) describes the process whereby somatic cells are directly converted in vitro or in vivo to a tissue-specific cell type, without passage through the iPSC intermediate state.4 In terms of therapy, direct reprogramming of scar-associated cardiac fibroblasts in vivo (formed after myocardial infarction) to non1070
Author Affiliations: University of Michigan Medical School, Ann Arbor (Rao); Prince of Wales Hospital, Randwick, New South Wales, Australia (Dlouhy). Corresponding Author: Rajesh C. Rao, MD, University of Michigan Medical School, 1000 Wall St, Brehm 8326, Ann Arbor, MI 48105 ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. 1. Mordwinkin NM, Lee AS, Wu JC. Patient-specific stem cells and cardiovascular drug discovery. JAMA. 2013;310(19):2039-2040. 2. Narsinh K, Narsinh KH, Wu JC. Derivation of human induced pluripotent stem cells for cardiovascular disease modeling. Circ Res. 2011;108(9):1146-1156. 3. Miura K, Okada Y, Aoi T, et al. Variation in the safety of induced pluripotent stem cell lines. Nat Biotechnol. 2009;27(8):743-745. 4. Qian L, Huang Y, Spencer CI, et al. In vivo reprogramming of murine cardiac fibroblasts into induced cardiomyocytes. Nature. 2012;485(7400):593-598. 5. Najm FJ, Lager AM, Zaremba A, et al. Transcription factor-mediated reprogramming of fibroblasts to expandable, myelinogenic oligodendrocyte progenitor cells. Nat Biotechnol. 2013;31(5):426-433.
In Reply Drs Rao and Dlouhy mention several valid points regarding the bottlenecks of iPSC derivation and suggest that direct reprogramming to induced cardiomyocytes (iCMs) may be a more cost-effective, efficient, and safe alternative. Transdifferentiation to iCMs presents both advantages and disadvantages compared with the use of iPSC-derived cardiomyocytes. We think that both of these methods offer significant potential for the clinical treatment of cardiac disease in addition to cardiovascular drug discovery. First, we recognize that the derivation of iPSCs from somatic cells has traditionally been a relatively inefficient process. However, recent advances in iPSC derivation have significantly improved reprogramming methods to near 100% efficiency within a span of less than 1 week.1 Even though direct differentiation is promising, transdifferentiation of human fibroblasts into iCMs is also a relatively inefficient method and the criteria to evaluate bona fide iCMs have yet to be standardized.2 For example, a recent study by Fu et al3 demonstrated that the majority of human iCMs are only partially reprogrammed to cardiac lineages and less than 1.5% of iCMs analyzed exhibit human cardiac
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
jama.com
are needed to build and sustain excellence, innovation, and methodological rigor in peer review research. Mario Malički, MD, MA Erik von Elm, MD, MSc Ana Marušić, MD, PhD Author Affiliations: Department of Research in Biomedicine and Health, University of Split School of Medicine, Split, Croatia (Malički, Marušić); Institute for Social and Preventive Medicine, University Hospital Lausanne, Lausanne, Switzerland (von Elm). Corresponding Author: Ana Marušić, MD, PhD, Department of Research in Biomedicine and Health, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia ([email protected]). Author Contributions: Dr Marušić had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: von Elm, Marušić. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Drafting of the manuscript: all authors. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: Malički. Administrative, technical, and material support: Malički, Marušić. Study supervision: von Elm, Marušić. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Marušić and von Elm are members of the Advisory Board of the Seventh International Congress on Peer Review and Biomedical Publication. Previous Presentation: This study was presented at the Seventh International Congress on Peer Review and Biomedical Publication, Chicago, Illinois, September 8-10, 2013. Additional Contributions: We thank the Esteve Foundation for organizing a Discussion Group on Editorial Research in Barcelona (Catalonia, Spain) on December 12-13, 2012, which gave us the idea for the study. We thank Annette Flanagin, RN, MA, and Drummond Rennie, MD, at JAMA for providing access to the abstracts and JAMA articles from the early Peer Review Congresses, for which they were not compensated. 1. Rennie D. Preface. In: Peer Review in Scientific Publishing. Papers from the First International Congress on Peer Review and Biomedical Publication. Chicago, IL: Council of Biology Editors; 1991. 2. National Library of Medicine. Medical Subject Headings: “Peer Review, Research.” http://www.ncbi.nlm.nih.gov/mesh/?term=peer+review%2C+ research. Accessed October 5, 2013. 3. Bossuyt PM, Reitsma JB, Bruns DE, et al; Standards for Reporting of Diagnostic Accuracy. Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. Clin Chem. 2003;49(1):1-6. 4. Dickersin K, Scherer R, Lefebvre C. Identifying relevant studies for systematic reviews. BMJ. 1994;309(6964):1286-1291. 5. Dickersin K. The existence of publication bias and risk factors for its occurrence. JAMA. 1990;263(10):1385-1389. 6. Scherer RW, Langenberg P, von Elm E. Full publication of results initially presented in abstracts. Cochrane Database Syst Rev. 2007;(2):MR000005.
COMMENT & RESPONSE
Mortality in Patients With Hypovolemic Shock Treated With Colloids or Crystalloids To the Editor The Colloids vs Crystalloids for the Resuscitation of the Critically Ill (CRISTAL) trial1 found no difference in 28day mortality but improved 90-day mortality in patients in the intensive care unit (ICU) with hypovolemic shock resuscitated using colloids (mainly hydroxyethyl starch solutions) vs crystalloids (mainly isotonic saline). The CRISTAL trial was unblinded and allocation of patients occurred by envelope ran-
domization using fixed block size, which may not have ensured allocation concealment. That adequate randomization may have failed and allocation of patients into the 2 intervention groups may have been skewed in the CRISTAL trial is supported by marked baseline imbalance in the numbers of patients that received crystalloids and colloids in the 12 hours prior to randomization. In a large trial like CRISTAL, such differences are unlikely to occur by chance. Lack of allocation concealment and blinding can introduce bias, which often leads to overestimation of intervention effects.2 Bias is also suggested because the results of the CRISTAL trial contrast with those of other recent trials with low risk of bias3,4 and a systematic review5 that showed increased use of renal replacement therapy, increased mortality, or both, with hydroxyethyl starch. Interpretation of the CRISTAL trial1 is further complicated by the variety of colloid and crystalloid solutions used in the 2 intervention groups. In addition, randomization may not have been preserved in the subgroup analyses by type of fluid received because the allocation to different types of fluids may have depended on trial site in addition to randomization. Anders Perner, MD, PhD Nicolai Haase, MD, PhD Jørn Wetterslev, MD, PhD Author Affiliations: Intensive Care Medicine, Copenhagen University Hospital, Copenhagen, Denmark. Corresponding Author: Anders Perner, MD, PhD, Copenhagen University Hospital, Blegdamsvej 9, DK-2100 Copenhagen, Denmark (anders.perner @regionh.dk). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Perner reported receiving research grants from CSL Behring and Fresenius Kabi; and payment for lectures from LBP SA. Dr Haase reported being a member of the steering committee of the Scandinavian Starch for Severe Sepsis/Septic Shock (6S) Trial, a publicly funded trial with support by B Braun Medical, which provided study fluid free of charge. No other disclosures were reported. 1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Savović J, Jones HE, Altman DG, et al. Influence of reported study design characteristics on intervention effect estimates from randomized, controlled trials. Ann Intern Med. 2012;157(6):429-438. 3. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 4. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134. 5. Zarychanski R, Abou-Setta AM, Turgeon AF, et al; Association of hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients requiring volume resuscitation: a systematic review and meta-analysis. JAMA. 2013;309(7):678-688.
To the Editor The CRISTAL trial1 requires scrutiny because its results contradict other high-quality evidence.2 The CRISTAL trial was stopped for futility based on no difference in 28-day
jama.com
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
1067
Letters
mortality, but reported numerically lower mortality for the colloids group. However, eFigure 1 in the article suggests lower mortality in the crystalloids group when the trial was stopped. eFigure 2 shows a sudden increase in probability of death at 28 days in both groups; this indicates either censoring (suggesting the denominator for 90-day mortality was wrong) or an unexplained and puzzling cluster of deaths on day 28 resulting in the mortality difference at 90 days. Because the trial was open label, it is important to demonstrate equality of resuscitation between the 2 groups as occurred in previous crystalloid vs colloid trials.3,4 Annane and colleagues 1 reported blood pressure only during the first 24 hours, which may be influenced by many factors in the ICU, including use of sedation and vasopressors. Other data such as daily heart rate, filling pressures, and urine output for at least the period of active resuscitation should be provided. eFigure 4c indicates a marked increase in the cardiovascular Sequential Organ Failure Assessment (SOFA) score from day 0 to day 1 in the crystalloids group, an effect not apparent in the larger blinded trials.3,4 This suggests that unblinded clinicians may have treated the 2 groups unequally. Hydroxyethyl starch, the predominant colloid used, causes renal injury.4,5 eFigure 4b demonstrates an increase in the renal SOFA score from day 0 to day 1 in the colloids but not the crystalloids group. The SOFA score is derived from serum creatinine level and urine output with increasing creatinine being a more reliable marker of renal injury. Annane et al1 should provide daily creatinine levels by treatment assignment so that renal injury can be properly assessed. The explanations offered for the results of the CRISTAL trial differing from larger blinded trials (that the recommended dose of starch was not exceeded and that patients in the crystalloids group received chloride-rich fluids [normal saline]) do not stand up to scrutiny. Patients in the Crystalloid vs Hydroxyethyl Starch Trial (CHEST) received on average only 10% of the recommended daily maximum dose of starch,4 and normal saline was the comparator for both the CHEST and the Saline vs Albumin Fluid Evaluation (SAFE) studies.3,4 Rinaldo Bellomo, MD, FCICM Simon Finfer, MD, FCICM John Myburgh, PhD, FCICM Author Affiliations: Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Australia (Bellomo); George Institute for Global Health, University of Sydney, Sydney, Australia (Finfer, Myburgh). Corresponding Author: Simon Finfer, MD, FCICM, University of Sydney, PO Box M201 Missenden Road, Camperdown, Australia 2050 (sfinfer@georgeinstitute .org.au). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Bellomo reported receiving personal fees and nonfinancial support from Gambro; grants and personal fees from Baxtter; and personal fees from Philips. Dr Finfer reported receiving institutional grants and travel reimbursement from Fresenius Kabi; honoraria for speaking at symposia sponsored by PPTA, which were paid to the International Sepsis Forum. Dr Myburgh reported receiving institutional payments for serving as a board member for Baxter; and receiving grants, payment for lectures, and travel expenses from Fresenius Kabi. No other disclosures were reported.
1068
1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Perel P, Roberts I, Ker K. Colloids versus crystalloids for fluid resuscitation in critically ill patients. Cochrane Database Syst Rev. 2013;2:CD000567. 3. Finfer S, Bellomo R, Boyce N, French J, Myburgh J, Norton R; SAFE Study Investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. N Engl J Med. 2004;350(22):2247-2256. 4. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 5. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134.
To the Editor Dr Annane and colleagues1 reported that 28-day mortality (primary end point) did not significantly differ between patients with hypovolemic shock assigned to various colloid fluid therapies (69% of whom received hydroxyethyl starch) vs crystalloid fluid therapies. They also reported that 90-day mortality (one of many secondary end points) was significantly higher with crystalloids. Annane et al1 appropriately acknowledged that the 90day mortality results were exploratory. However, potential users of hydroxyethyl starch need clarity on the robustness of this finding and whether it is consistent with the published literature. Such clarity is particularly necessary given the recent decision by the European Medicines Agency allowing hydroxyethyl starch use in patients with hypovolemic shock and bleeding but not in patients with sepsis, burn, or critically illness. With regard to consistency, the results of this trial contradict 3 randomized controlled trials in patients with critically illness or sepsis in which renal morbidity or mortality was significantly higher with hydroxyethyl starch compared with crystalloid therapy.2-4 Notably, the CRISTAL trial1 is the only study to show a significant survival benefit for hydroxyethyl starch vs another resuscitation fluid. For a secondary end point to be convincing when the primary outcome is not significant, the P value should ideally remain robust after correcting for multiple comparisons. Because at least 7 secondary end points were examined, the authors should provide a P value for 90-day mortality corrected for multiple comparisons. In addition, the 90-day end point was added midway through the 9-year trial,5 further obscuring how to interpret the finding. The 90-day cumulative incidence curve shows increases in both treatment groups at 28 days, suggesting a brisk, unexplained accumulation of deaths at that point. Given that this end point in some patients was collected retrospectively, Annane et al1 should describe how the missing mortality data between days 28 and 90 were handled. The sequential triangular test figure shows a sharp decrease in the curve between the fifth and sixth interim analyses, and the authors should comment on this unusual pattern. In addition, in light of the recent European Medicines Agency decision, a test of interaction between survival difference at 90 days between the 2 fluid therapy groups
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
jama.com
Letters
and the presence vs absence of shock due to bleeding would be helpful to determine whether hydroxyethyl starch has a different effect on bleeding in patients with hypovolemic shock than it does in other critically ill patients. Christian Brun-Buisson, MD Junfeng Sun, PhD Charles Natanson, MD Author Affiliations: Service de Réanimation Médicale, GH Henri Mondor, Créteil, France (Brun-Buisson); Department of Critical Care Medicine, National Institutes of Health Clinical Center, Bethesda, Maryland (Sun, Natanson). Corresponding Author: Christian Brun-Buisson, MD, Service de Réanimation Médicale, GH Henri Mondor, 51 Ave de Lattre de Tassigny, 9010 Créteil, France ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Brun-Buisson reported receiving a grant from the European Commission. No other disclosures were reported. Disclaimer: The opinions expressed in this article are those of the authors and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the US government. 1. Annane D, Siami S, Jaber S, et al; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013;310(17):1809-1817. 2. Brunkhorst FM, Engel C, Bloos F, et al; German Competence Network Sepsis (SepNet). Intensive insulin therapy and pentastarch resuscitation in severe sepsis. N Engl J Med. 2008;358(2):125-139. 3. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911. 4. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134. 5. ClinicalTrials.gov website. CRISTAL: colloids compared to crystalloids in fluid resuscitation of critically ill patients: a multinational randomised controlled trial. http://www.clinicaltrials.gov/ct2/show/NCT00318942. Accessed October 3, 2013.
In Reply Dr Perner and colleagues suggest that allocation concealment was not ensured in the CRISTAL trial. However, procedures were in place to hide the allocation sequence until assignment. Sequentially numbered, sealed, and opaque envelopes were used. An envelope assigned to a patient was opened only after the investigator wrote patient information on it. The signed inclusion sheet with patient and randomization details was faxed to the coordinating center, allowing monitoring of treatment allocation to unique patients in appropriate order. Only 6 errors in envelope assignment were found, corresponding to simultaneous inclusion of a patient by multiple investigators in the same center. This process ensured a low risk of bias.1 Perner and colleagues also suggest that the 2 groups were not balanced at baseline. However, imbalances in a randomized trial occur by chance. All of the baseline variables except for fluid administration prior to ICU admission were well balanced between the 2 groups. Dr Bellomo and colleagues suggest that physicians favored management of patients assigned to colloids vs crystal-
loids. In practice, the 2 treatment groups did not differ with regard to time to initiation of a vasopressor (mean [SD] of 0.8 [4.9] days for the colloids group vs 0.5 [1.9] days for the crystalloids group, P = .82), mechanical ventilation (mean [SD] of 0.4 [5.2] days for the colloids group vs 0.2 [2.2] days for the crystalloids group, P = .89), or renal replacement therapy (mean [SD] of 2.3 [1.5] days for the colloids group vs 2.2 [1.4] days for the crystalloids group, P = .71). Moreover, the study was designed to show a higher risk of death and kidney injury with colloids than with crystalloids, which was in keeping with the beliefs of the investigators throughout the recruitment period. Dr Brun-Buisson and colleagues and Bellomo and colleagues point out a brisk increase in the number of deaths at 28 days. We do not have a definite explanation for this accumulation of deaths, which occurred in both treatment groups. There were no missing data for 90-day mortality or errors in the denominator. Decision to withdraw care preceded death prior to 28 days in 11% of the patients treated with colloids and 13% of patients treated with crystalloids, and preceded death after 28 days in 9% of both groups. The decrease in the sequential triangular test figure between the fifth and sixth interim analyses is a pattern that has been observed previously.2 All 3 groups of writers incorrectly stated that the CRISTAL trial found results contradictory to trials that compared a starch solution with a single crystalloid.3-5 None of these trials3-5 or the CRISTAL trial found significant differences in 28-day mortality between crystalloids and colloids. The 90-day mortality outcome was secondary for the Efficacy of Volume Substitution and Insulin Therapy in Severe Sepsis (VISEP) trial and the CRISTAL trial. Only the Scandinavian Starch for Severe Sepsis/Septic Shock (6ES) trial showed a barely significant increase in 90day mortality with colloids (relative risk [RR], 1.17; 95% CI, 1.01-1.36).3 In the other 2 trials, death rates at 90 days were not different between groups.3,5 Thus, any mortality difference at 90 days between colloids and crystalloids remains uncertain. Our findings of fewer deaths at 90 days could only be considered exploratory because it was a secondary outcome. Correction for multiple analyses was not planned for the secondary outcomes. There was no heterogeneity in the treatment effect on mortality in nontraumatic hemorrhagic shock vs nonhemorrhagic shock (P = .10). The prevalence of renal replacement therapy was significantly increased with starch in the VISEP 3 and 6ES trials.4 In CHEST,5 this risk was not statistically significant (RR, 1.21; 95% CI, 1.00-1.45), fewer patients receiving starch than isotonic saline developed renal injury, and the proportion of patients who developed renal failure was not different. In the CRISTAL trial, there was no difference between treatment groups in creatinine levels over time up to 28 days. Thus, there was no marked difference in renal adverse events between CHEST and the CRISTAL trial, which are the 2 largest trials on fluid therapy. Djillali Annane, MD, PhD Sylvie Chevret, MD, PhD
jama.com
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
1069
Letters
3. Brunkhorst FM, Engel C, Bloos F, et al; German Competence Network Sepsis (SepNet). Intensive insulin therapy and pentastarch resuscitation in severe sepsis. N Engl J Med. 2008;358(2):125-139.
proliferative functional cardiomyocytes may offer an advantage because intermediate tumorigenic cells are not generated and the reprogrammed cells can mature in the in vivo environment.4 However, directly reprogrammed, terminally differentiated postmitotic cells provide only a limited supply of tissues for drug and toxicity screening. Instead, nonpluripotent, tissuespecific precursors could be generated, such as cardiomyocyte progenitors or oligodendrocyte progenitors.5 These expandable cells can generate clinically significant amounts of therapeutic cell types yet they limit the dangers and inefficiencies associated with generation of unwanted cell types from iPSCs. Direct reprogramming is a potentially more costeffective, efficient, and safer alternative approach to iPSCbased technology.
4. Myburgh JA, Finfer S, Bellomo R, et al; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med. 2012;367(20):19011911.
Rajesh C. Rao, MD Brian J. Dlouhy, MD
Author Affiliations: Raymond Poincaré Hospital, University of Versailles, Garches, France (Annane); Saint Louis Hospital, Paris, France (Chevret). Corresponding Author: Djillali Annane, MD, PhD, Raymond Poincaré Hospital, University of Versailles, 104 Blvd Raymond Poincaré, 92380 Garches, France ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. 1. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. http://www.cochrane-handbook.org. Accessibility verified February 11, 2014. 2. Hulot JS, Cucherat M, Charlesworth A, et al. Planning and monitoring of placebo-controlled survival trials: comparison of the triangular test with usual interim analyses methods. Br J Clin Pharmacol. 2003;55(3):299-306.
5. Perner A, Haase N, Guttormsen AB, et al; 6S Trial Group; Scandinavian Critical Care Trials Group. Hydroxyethyl starch 130/0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med. 2012;367(2):124-134.
Stem Cells and Cardiovascular Drug Development To the Editor We are hopeful that induced pluripotent stem cells (iPSCs) will lead to powerful drug discovery platforms based on their ability to model disease at the cellular level and will serve as a reservoir of transplantable tissues for many diseases. Dr Mordwinkin and colleagues1 highlighted these aspects to assert that iPSC technology may reduce preclinical drug development times and more accurately predict efficacy and toxicity of novel or off-label therapeutic agents in human cardiomyocytes. However, iPSC-based technology is not the ideal platform for drug and toxicity screening or for the derivation of transplantable tissues. Currently, somatic cell reprogramming to iPSCs takes several weeks, in part because the process is laborious, with reprogramming efficiencies ranging from 0.005% to 0.01%.2 Although more efficient, directed human iPSC differentiation to terminally differentiated cell types in vitro requires several additional weeks or months. 2 Moreover, during many of the steps in direc ted iPSC differentiation, unwanted intermediate cell types with proliferative and tumorigenic properties are produced. 3 Therefore, iPSCbased technology remains expensive, time consuming, and in the context of therapeutic transplantation, potentially risky due to the possibility of iPSC-derived tumorigenic cells in the graft. For these reasons, safer and more cost-effective approaches to drug discovery, toxicity screening, and generation of therapeutically valuable cell types should use strategies that skip the iPSC stage altogether. Direct reprogramming (also known as lineage conversion or transdifferentiation) describes the process whereby somatic cells are directly converted in vitro or in vivo to a tissue-specific cell type, without passage through the iPSC intermediate state.4 In terms of therapy, direct reprogramming of scar-associated cardiac fibroblasts in vivo (formed after myocardial infarction) to non1070
Author Affiliations: University of Michigan Medical School, Ann Arbor (Rao); Prince of Wales Hospital, Randwick, New South Wales, Australia (Dlouhy). Corresponding Author: Rajesh C. Rao, MD, University of Michigan Medical School, 1000 Wall St, Brehm 8326, Ann Arbor, MI 48105 ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. 1. Mordwinkin NM, Lee AS, Wu JC. Patient-specific stem cells and cardiovascular drug discovery. JAMA. 2013;310(19):2039-2040. 2. Narsinh K, Narsinh KH, Wu JC. Derivation of human induced pluripotent stem cells for cardiovascular disease modeling. Circ Res. 2011;108(9):1146-1156. 3. Miura K, Okada Y, Aoi T, et al. Variation in the safety of induced pluripotent stem cell lines. Nat Biotechnol. 2009;27(8):743-745. 4. Qian L, Huang Y, Spencer CI, et al. In vivo reprogramming of murine cardiac fibroblasts into induced cardiomyocytes. Nature. 2012;485(7400):593-598. 5. Najm FJ, Lager AM, Zaremba A, et al. Transcription factor-mediated reprogramming of fibroblasts to expandable, myelinogenic oligodendrocyte progenitor cells. Nat Biotechnol. 2013;31(5):426-433.
In Reply Drs Rao and Dlouhy mention several valid points regarding the bottlenecks of iPSC derivation and suggest that direct reprogramming to induced cardiomyocytes (iCMs) may be a more cost-effective, efficient, and safe alternative. Transdifferentiation to iCMs presents both advantages and disadvantages compared with the use of iPSC-derived cardiomyocytes. We think that both of these methods offer significant potential for the clinical treatment of cardiac disease in addition to cardiovascular drug discovery. First, we recognize that the derivation of iPSCs from somatic cells has traditionally been a relatively inefficient process. However, recent advances in iPSC derivation have significantly improved reprogramming methods to near 100% efficiency within a span of less than 1 week.1 Even though direct differentiation is promising, transdifferentiation of human fibroblasts into iCMs is also a relatively inefficient method and the criteria to evaluate bona fide iCMs have yet to be standardized.2 For example, a recent study by Fu et al3 demonstrated that the majority of human iCMs are only partially reprogrammed to cardiac lineages and less than 1.5% of iCMs analyzed exhibit human cardiac
JAMA March 12, 2014 Volume 311, Number 10
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Oakland University User on 06/02/2015
jama.com
