The Journal of Arthroplasty xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Early Death Following Primary Total Hip Arthroplasty Mark D. Jones, MBBS, MRCS, Michael C. Parry, BSc, MBChB, MD, FRCS, Michael R. Whitehouse, BSc, MSc, MBChB, PhD, FRCS, Ashley W. Blom, MD, PhD, FRCS Musculoskeletal Research Unit, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK
a r t i c l e
i n f o
Article history: Received 14 December 2013 Accepted 3 February 2014 Available online xxxx Keywords: total hip arthroplasty mortality survivorship analysis surgical mortality surgical outcomes
a b s t r a c t This study aims to describe the timing, cause of death, and excess surgical mortality associated with primary total hip arthroplasty when compared to a population awaiting primary total hip arthroplasty. Mortality rates were calculated at cutoffs of 30 and 90 days post-operation or following the addition to the waiting list. Cause of death was recorded from the death certificate. An excess surgical mortality of 0.256% at 30 days (P = 0.002) and 0.025% at 90 days post-operation (P = 0.892), unaffected by age or gender, was seen with myocardial infarction and pneumonia the cause of death in the majority of cases. By using a more appropriate control population, an excess surgical mortality at 30 days post-operation is demonstrated; the effect diminishes at 90 days post-operation. © 2014 Elsevier Inc. All rights reserved.
Total hip arthroplasty (THA) is widely accepted as an efficacious [1] and cost-effective [2,3] treatment for debilitating arthritis of the hip. Despite its universal acceptance in terms of safety, mortality remains a recognized complication following THA [4] with death rates in the region of 1%–2% at 90 days post-operation [5–8] and 15%–33% at 6–10 years following THA [4,8–10]. However, accurate assessments of the increased risk of mortality above baseline following THA are unclear. Mortality rates following THA have often been reported by comparing death rates to that of the general population or to an age and sex matched population. By using these comparators, many of these studies consistently demonstrate an apparent improved survivorship in THA populations when compared to comparable, non-arthroplasty populations, or samples of the population as a whole [4,5,11,12], though this benefit does diminish with time following operation [5,9]. This feature would suggest a protective effect of arthroplasty on the incidence of death in these populations [4,8]. An alternative explanation is the so-called “well” patient effect in that the arthroplasty population is not comparable to the population as a whole as patients with significant comorbidity are denied surgery and thus excluded from the arthroplasty population. Therefore, studies comparing the death rate in populations of patients undergoing primary THA with sample populations can underestimate the increased risk of mortality attributable to surgery. This reduces the
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.02.002. Reprint requests: Michael C. Parry, BSc, MBChB, MD, FRCS, Musculoskeletal Research Unit, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Westbury On Trym, Bristol BS10 5NB, UK.
clarity of advice given to patients undergoing THA in terms of their risk of death. In order to account for this “well” patient phenomenon, we have previously compared 30- and 90-day mortality in patients undergoing primary total knee arthroplasty (TKA) with a population of patients awaiting the same procedure and found that mortality is significantly increased [13]. Here we report a study using the same methodology in THA patients. The aim of this study was to describe the timing and cause of mortality following primary THA and to ascertain the amount of excess mortality above baseline. A recent study has shown that excess mortality is highest in the first 24 hours after THA and declines to baseline over the first 90 post-operative days [14]. We thus compared the death rate in this group with the 30- and 90-day mortality in a population of patients who were added to the waiting list for the same procedure.
Materials and Methods All patients undergoing primary THA in a single unit formed the arthroplasty population for the study. Procedures were completed between January 2006 and December 2011 allowing sufficient time frame for death to be recorded. Details regarding patient age, sex and date of death where applicable, were recorded. A second data set was prepared comprising all patients added to the hospital waiting list for the same procedure. Again, patient demographics were recorded as were date of removal from the waiting list as well as reason for removal. Reasons for exclusion were as follows. Patients who were on the waiting list for less than 30 days were excluded from the 30-day
0883-5403/0000-0000$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2014.02.002
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
2
M.D. Jones et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
survivorship analysis (3.3%). Those on the waiting list for more than 30 but less than 90 days were excluded from the 90-day analysis (33.7%). Patients undergoing bilateral procedures, either synchronous or sequential, were also excluded. All patients were seen prior to their operation in a pre-assessment clinic. At this time, an assessment of comorbidity was performed at which stage medical reasons for exclusion from surgery were identified. These included poorly controlled hypertension, diabetes, ischemic heart disease, respiratory illness and renal dysfunction. Patients for whom surgery was deemed to carry excessive risk were removed from the waiting list and therefore, were not included in either the waiting list group or the surgical group. For those in whom medical optimization was required and who were relisted for THA within the study period, only the subsequent relisting was used for the survivorship analysis. All patients were drawn from the same population. Therefore, many of the patients in the arthroplasty population were included in the waiting list population if they had been on the waiting list for 30 days or more. Following exclusion, 3621 patients in the waiting list group were available for the 30-day survivorship analysis and 2131 patients for the 90-day analysis. In the arthroplasty group, 3128 patients were available for both the 30- and 90-day survivorship analysis. Retrieval of information pertaining to death was completed as previously described [13]. Using the Demographics Batch Service through the National Health Service (NHS) Connecting for Health, the details of the two populations were traced against the national Personal Demographics Service which stores information regarding demographic characteristics of all users of the NHS within the United Kingdom (UK). It was possible to identify patients who had died within each group as well as the date of death. In each group, patients who died within 90 days either after the operation or after being listed for the operation were identified. Death certificates for these patients were retrieved from the UK General Register Office, and the cause of death was identified. In the population of patients undergoing primary THA, surgical technique was at the discretion of the operating surgeon. The method of anesthesia was at the discretion of the anesthetist. All patients received prophylactic antibiotics as per hospital protocol. The use of chemical thromboprophylaxis and intermittent pneumatic compression devices depended on the operating surgeon. All patients were fitted with graduated compression/anti-embolism stockings at the time of surgery and were advised to wear them for 6 weeks after surgery unless contraindicated. Mortality rates were calculated on the basis of cutoff points of 30 and 90 days following the date of surgery or the date of listing. Confidence intervals were calculated with the score method [15]. A chi-squared test was used to compare the proportions of patients who died between the waiting list and THA groups. Data distribution was checked with a D'Agostino and Pearson normality test. Where data were not normally distributed, central tendency is described with the median and inter-quartile ranges (IQR). Where data were normally distributed, central tendency was described with the mean and standard deviation. Normally distributed data comparison was performed with parametric tests and non-normally distributed data with non-parametric tests (Mann–Whitney test). For illustrative purposes, patients in each group were stratified according to age and the mortality rate and day-by-day mortality were calculated. A multiple regression model was used to determine if age or gender influenced the risk of death in the waiting list or THA groups at 90 days.
the mortality rate of the waiting list group was zero. The excess surgical mortality at 30 days was 0.256% (95% confidence interval: 0.130% to 0.398%); this difference was significant (P = 0.002). The 90-day mortality of patients placed on the waiting list for primary THA was 0.422% (95% confidence interval: 0.222% to 0.801%), whereas following primary THA it was 0.448% (95% confidence interval: 0.267% to 0.750%). The odds ratio was 1.06 (95% confidence interval: 0.458 to 2.453). The excess surgical mortality at 90 days was 0.025% (95% confidence interval: − 0.051% to 0.044%); this difference was not significant (P = 0.892). In the 30-day comparison the median age was 69.0 years (IQR 61.0–76.0) in those on the waiting list and 69.0 years (IQR 59.0–76.0) for those undergoing THA. In the 90-day comparison the median age was 69.0 years (IQR 61.0–76.0) in those on the waiting list and 69.0 years (IQR 59.0–76.0) for those undergoing THA. Neither of these differences was significant (P N 0.05). There was no significant difference in gender distribution in the 30-day comparison (P N 0.05; waiting list group 38.0% male, 42.0% female; THA group 38.5% male, 41.5% female) or the 90-day comparison (P N 0.05; waiting list group 36.7% male, 43.3% female; THA group 38.4% male, 41.6% female). The multiple regression model revealed that in the waiting list group at 90 days neither age (P = 0.146) nor gender (P = 0.423) influenced the risk of death. Similar findings were found in the THA group (age P = 0.307; gender P = 0.326), though the incidence of death in the over 75 years group was more common than the population under 75 years of age (0.61% versus 0.33%). The day-to-day 90-day mortality for all age groups and for those under and over the age of 75 years is shown in Figs. 1, 2 and 3. Death certificates were available for the 14 patients who died within 90 days of surgery and the 9 patients who died within 90 days of being added to the waiting list. The cause of death as detailed on the death certificate in each population is shown in Table 1. Myocardial infarction and pneumonia accounted for the majority of the postoperative deaths. Discussion The current study presents data on the incidence of death in the early post-operative period following primary THA and compares it to the incidence of death in a population of patients on the waiting list for the same period. The primary focus of this study was to identify the importance of utilizing an appropriate comparison population when identifying the increased risk of death following THA. Using the same methodology as used here, we have previously demonstrated an excess surgical mortality in association with TKR [13]. We have now
Results The 30-day mortality of patients placed on the waiting list for primary THA was 0.000% (95% confidence interval: 0.000% to 0.106%), whereas following primary THA it was 0.256% (95% confidence interval: 0.130% to 0.504%). The odds ratio could not be calculated, as
Fig. 1. Ninety-day mortality for patients undergoing primary THA compared to those remaining on the waiting list for the same procedure.
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
M.D. Jones et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
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Table 1 Cause of Death as Detailed on the Death Certificates of Patients Who Died Within 90 Days of Undergoing Primary Total Hip Arthroplasty or Within 90 Days of Being Added to the Waiting List for a Primary Total Hip Arthroplasty. Number of Deaths Cause of Death Bronchopneumia Acute myocardial event Multiorgan failure Metastatic carcinoma Sepsis Peritonitis secondary to perforated diverticulum Gastrointestinal hemorrhage secondary to perforated duodenal ulcer Acute myeloid leukaemia Chronic lymphocytic leukaemia Total Fig. 2. Ninety-day mortality in patients under 75 years of age undergoing primary total hip arthroplasty in comparison to those on the waiting list for the same procedure.
demonstrated a similar finding for patients undergoing primary THA, although the effect seems to be confined to the first 30 days after surgery. The 30-day mortality in the operative group in this study is comparable to that observed by others [16] but is lower than that reported elsewhere in the literature [4,7,12,17–19]. The 90-day mortality in the operative group was comparable to that demonstrated by Aynardi et al [16] and Cusick and Beverland [20] but was lower than that demonstrated by other studies [4–7,17]. The National Joint Registry for England and Wales analysis of mortality following 409,000 primary hip arthroplasties for osteoarthritis reported a secular decline in 90-day mortality from 0.6% in 2003 to 0.3% in 2011 [14]. In addition to the well-recognized decline in mortality that has resulted in an aging population, these differences may well be explained by improvements in orthopedic practice that have evolved in recent years. Improvements in anesthesia and post-operative pain management, particularly the use of hypotensive neuroaxial anesthesia techniques have greatly improved mortality from postoperative cardiorespiratory complications [21–23]. The use of both mechanical and chemical thromboprophylaxis is increasing and both are independently associated with reduced mortality [14]. Postoperative care has evolved with an increasing emphasis on early mobilization, improved analgesia and accelerated discharge. All these factors may decrease the risk of thromboembolism and pneumonia [24–26].
Fig. 3. Ninety-day mortality in patients 75 years and older undergoing primary total hip arthroplasty in comparison to those on the waiting list for the same procedure.
Arthroplasty Population
Waiting List Population
5 (36%) 5 (36%) 2 (14%) 2 (14%) 0 0 0
1 (11%) 1 (11%) 0 0 3 (33%) 1 (11%) 1 (11%)
0 0 14
1 (11%) 1 (11%) 9
Percentages are based on total number of deaths in each population.
Improvements in survival in the modern arthroplasty era may also be explained by improved pre-operative assessment of patients. The identification and optimization of significant risk factors for poor outcome following arthroplasty surgery, especially cardiovascular, respiratory and renal comorbidities, have been shown to improve mortality following surgery [27]. We have demonstrated an excess mortality at 30 days of 0.256%, but the effect was not significant at 90 days, when death in the operative group is compared to death in a comparable population awaiting the same procedure. This finding is in contrast to the often demonstrated phenomenon that patients undergoing arthroplasty procedures have improved survivorship when compared to control populations. This can be explained by looking at the control population rather than the arthroplasty population. Barrett et al [5] demonstrated an improved survivorship at 90 days when comparing patients undergoing primary hip arthroplasty with a sample of the general population. Lie et al [4] found a similar outcome when comparing long-term survivorship following THA with the general population at 8 years following surgery. Indeed, when using alternative measures such as standardized mortality ratios or age controls, the effect remains [11,12]. This can be explained by the “well” patient effect whereby patients are denied elective surgery if they are deemed to be medically unfit, thereby selecting a surgical cohort with better health than the general population. The cause of death in the arthroplasty population in this study is in keeping with those described by others with the majority of deaths resulting from cardiac events or bronchopneumonia [17]. In comparison, the distribution of causes of death in the waiting list group was much more diverse. These included perforation of viscus and sepsis, which would not have been identified on pre-operative assessment. Of note, fatal pulmonary embolus did not feature as a cause of death in the arthroplasty population. This is in contrast to the previously reported incidence of fatal embolic events following lower limb arthroplasty [28–30] and suggests that fatal pulmonary embolus is a rare event following primary THA. An extremely low incidence of fatal pulmonary embolus following THA has previously been reported [20,31]. Patents in the arthroplasty population of this study did not receive a standardized thromboprophylaxis regimen but all received both mechanical and chemical thromboprophylaxis, so conclusions about the efficacy or otherwise of any particular pharmacological or mechanical intervention, cannot be made. Rather, suffice to say, in the modern era, a combination of factors have combined to reduced fatal thrombotic events following elective THA to a rare occurrence. Using a multivariate analysis model, we have demonstrated no significant effect of either age or gender on the incidence of death at 90 days between the arthroplasty and waiting list populations. However, death in the operated group was more common in the more elderly population. Increasing age and male gender are well
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
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known to be associated with increased post-operative mortality [4,12,14,17,32], but our sample size was probably too small to demonstrate this. In summary, by using an appropriate control population, we have demonstrated that THA is associated with a significant excess surgical mortality at 30 days post-operation, but this effect diminishes by 90 days. Patients should be counseled accurately about the magnitude of this risk and efforts to decrease mortality should concentrate on the early post-operative period. Acknowledgments No further authors or contributors other than those stated were involved in the execution or preparation of this manuscript. No sources of funding were required for the execution or preparation of this manuscript. No sponsors were required for this study and none of the authors were involved with funding sources or sponsors for the execution of this study. Ethical approval was not required for this study. References 1. Ethgen O, Bruyère O, Richy F, et al. Health-related quality of life in total hip and total knee arthroplasty: a qualitative and systematic review of the literature. J Bone Joint Surg Am 2004;86(5):963. 2. Daigle ME, Weinstein AM, Katz JN, et al. The cost-effectiveness of total joint arthroplasty: a systematic review of the literature. Best Pract Res Clin Rheumatol 2012;26(5):649. 3. Chang RW. A cost-effectiveness analysis of total hip arthroplasty for osteoarthritis of the hip. JAMA 1996;275(11):858. 4. Lie SA, Engesaeter LB, Havelin LI, et al. Mortality after total hip replacement: 0–10year follow-up of 39,543 patients in the Norwegian Arthroplasty Register. Acta Orthop 2000;71(1):19. 5. Barrett J, Losina E, Baron JA, et al. Survival following total hip replacement. J Bone Joint Surg Am 2005;87(9):1965. 6. Mahomed NN, Barrett JA, Katz JN, et al. Rates and outcomes of primary and revision total hip replacement in the United States Medicare Population. J Bone Joint Surg Am 2003;85(1):27. 7. Pedersen AB, Baron JA, Overgaard S, et al. Short- and long-term mortality following primary total hip replacement for osteoarthritis: a Danish nationwide epidemiological study. J Bone and Joint Surgery Br 2011;93-B(2):172. 8. Holmberg S. Life expectancy after total hip arthroplasty. J Arthroplasty 1992 Jun;7(2):183. 9. Visuri T, Pulkkinen P, Turula KB, et al. Life expectancy after hip arthroplasty: case– control study of 1018 cases of primary arthrosis. Acta Orthop Scand 1994;65(1):9. 10. Garellick G, Malchau H, Herberts P, et al. Life expectancy and cost utility after total hip replacement. Clin Orthop Relat Res 1998;346:141. 11. Paavolainen P, Pukkala E, Pulkkinen P, et al. Causes of death after total hip arthroplasty. J Arthroplasty 2002;17(3):274.
12. Whittle J, Steinberg EP, Anderson GF, et al. Mortality after elective total hip arthroplasty in elderly Americans. Age, gender, and indication for surgery predict survival. Clin Orthop Relat Res 1993;295:119. 13. Parry MC, Smith AJ, Blom AW. Early death following primary total knee arthroplasty. J Bone Joint Surg Am 2011;93(10):948. 14. Hunt LP, Ben-Shlomo B, Clarke EM, et al. 90-day mortality after 409 096 total hip replacements for osteoarthritis, from the National Joint Registry for England and Wales: a retrospective analysis. Lancet 2013;382(9898):1097. 15. Wilson EB. Probable inference, the law of succession, and statistical inference. Journal of the American Statistical Association. Taylor & Francis Group; 1927;22(158):209–12 16. Aynardi M, Pulido L, Parvizi J, et al. Early mortality after modern total hip arthroplasty. Clin Orthop Relat Res 2008;467(1):213. 17. Blom A, Pattison G, Whitehouse S, et al. Early death following primary total hip arthroplasty: 1,727 procedures with mechanical thrombo-prophylaxis. Acta Orthop 2006;77(3):347. 18. Parvizi J, Johnson BG, Rowland C, et al. Thirty-day mortality after elective total hip arthroplasty. J Bone Joint Surg Am 2001;83-A(10):1524. 19. Coventry MB, Beckenbaugh RD, Nolan D, et al. 2,012 Total hip arthroplasties: a study of postoperative course and early complications. J Bone Joint Surg Am 1974;56(2):273. 20. Cusick LA, Beverland DE. The incidence of fatal pulmonary embolism after primary hip and knee replacement in a consecutive series of 4253 patients. J Bone Joint Surg Br 2009;91(5):645. 21. Lieberman JR, Huo MM, Hanway J, et al. The prevalence of deep venous thrombosis after total hip arthroplasty with hypotensive epidural anesthesia. J Bone Joint Surg Am 1994;76(3):341. 22. Sharrock NE, Cazan MG, Hargett MJ, et al. Changes in mortality after total hip and knee arthroplasty over a ten-year period. Anesth Analg 1995;80:242. 23. Macfarlane AJR, Prasad GA, Chan VWS, et al. Does regional anaesthesia improve outcome after total hip arthroplasty? A systematic review. Br J Anaesth 2009;103(3):335. 24. Andersen LJ, Poulsen T, Krogh B, et al. Postoperative analgesia in total hip arthroplasty: a randomized double-blinded, placebo-controlled study on peroperative and postoperative ropivacaine, ketorolac, and adrenaline wound infiltration. Acta Orthop 2007;78(2):187. 25. Ranawat AS, Ranawat CS. Pain management and accelerated rehabilitation for total hip and total knee arthroplasty. J Arthroplasty 2007;22(7 Suppl 3):12. 26. Wylde V, Blom AW, Bolink S, et al. Assessing function in patients undergoing joint replacement: a study protocol for a cohort study. BMC Musculoskelet Disord 2012;13(1):1. 27. Parvizi J, Mui A, Purtill JJ, et al. Total joint arthroplasty: when do fatal or near-fatal complications occur? J Bone Joint Surg Am 2007;89(1):27. 28. Wood M, Mantilla CB, Horlocker TT, et al. Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty. Anesthesiology 2002;96(5):1140. 29. Phillips CB, Barrett JA, Losina E, et al. Incidence rates of dislocation, pulmonary embolism, and deep infection during the first six months after elective total hip replacement. J Bone Joint Surg Am 2003;85(1):20. 30. Howie C, Hughes H, Watts AC. Venous thromboembolism associated with hip and knee replacement over a ten-year period: a population-based study. J Bone Joint Surg Br 2005;87(12):1675. 31. Parry M, Wylde V, Blom AW. Ninety-day mortality after elective total hip replacement: 1549 patients using aspirin as thromboprophylaxis. J Bone Joint Surg Br 2008;90-B:305. 32. Tarity TD, Herz AL, Parvizi J, et al. Ninety-day mortality after hip arthroplasty. J Arthroplasty 2006;21(6):60.
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Early Death Following Primary Total Hip Arthroplasty Mark D. Jones, MBBS, MRCS, Michael C. Parry, BSc, MBChB, MD, FRCS, Michael R. Whitehouse, BSc, MSc, MBChB, PhD, FRCS, Ashley W. Blom, MD, PhD, FRCS Musculoskeletal Research Unit, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK
a r t i c l e
i n f o
Article history: Received 14 December 2013 Accepted 3 February 2014 Available online xxxx Keywords: total hip arthroplasty mortality survivorship analysis surgical mortality surgical outcomes
a b s t r a c t This study aims to describe the timing, cause of death, and excess surgical mortality associated with primary total hip arthroplasty when compared to a population awaiting primary total hip arthroplasty. Mortality rates were calculated at cutoffs of 30 and 90 days post-operation or following the addition to the waiting list. Cause of death was recorded from the death certificate. An excess surgical mortality of 0.256% at 30 days (P = 0.002) and 0.025% at 90 days post-operation (P = 0.892), unaffected by age or gender, was seen with myocardial infarction and pneumonia the cause of death in the majority of cases. By using a more appropriate control population, an excess surgical mortality at 30 days post-operation is demonstrated; the effect diminishes at 90 days post-operation. © 2014 Elsevier Inc. All rights reserved.
Total hip arthroplasty (THA) is widely accepted as an efficacious [1] and cost-effective [2,3] treatment for debilitating arthritis of the hip. Despite its universal acceptance in terms of safety, mortality remains a recognized complication following THA [4] with death rates in the region of 1%–2% at 90 days post-operation [5–8] and 15%–33% at 6–10 years following THA [4,8–10]. However, accurate assessments of the increased risk of mortality above baseline following THA are unclear. Mortality rates following THA have often been reported by comparing death rates to that of the general population or to an age and sex matched population. By using these comparators, many of these studies consistently demonstrate an apparent improved survivorship in THA populations when compared to comparable, non-arthroplasty populations, or samples of the population as a whole [4,5,11,12], though this benefit does diminish with time following operation [5,9]. This feature would suggest a protective effect of arthroplasty on the incidence of death in these populations [4,8]. An alternative explanation is the so-called “well” patient effect in that the arthroplasty population is not comparable to the population as a whole as patients with significant comorbidity are denied surgery and thus excluded from the arthroplasty population. Therefore, studies comparing the death rate in populations of patients undergoing primary THA with sample populations can underestimate the increased risk of mortality attributable to surgery. This reduces the
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.02.002. Reprint requests: Michael C. Parry, BSc, MBChB, MD, FRCS, Musculoskeletal Research Unit, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Westbury On Trym, Bristol BS10 5NB, UK.
clarity of advice given to patients undergoing THA in terms of their risk of death. In order to account for this “well” patient phenomenon, we have previously compared 30- and 90-day mortality in patients undergoing primary total knee arthroplasty (TKA) with a population of patients awaiting the same procedure and found that mortality is significantly increased [13]. Here we report a study using the same methodology in THA patients. The aim of this study was to describe the timing and cause of mortality following primary THA and to ascertain the amount of excess mortality above baseline. A recent study has shown that excess mortality is highest in the first 24 hours after THA and declines to baseline over the first 90 post-operative days [14]. We thus compared the death rate in this group with the 30- and 90-day mortality in a population of patients who were added to the waiting list for the same procedure.
Materials and Methods All patients undergoing primary THA in a single unit formed the arthroplasty population for the study. Procedures were completed between January 2006 and December 2011 allowing sufficient time frame for death to be recorded. Details regarding patient age, sex and date of death where applicable, were recorded. A second data set was prepared comprising all patients added to the hospital waiting list for the same procedure. Again, patient demographics were recorded as were date of removal from the waiting list as well as reason for removal. Reasons for exclusion were as follows. Patients who were on the waiting list for less than 30 days were excluded from the 30-day
0883-5403/0000-0000$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2014.02.002
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
2
M.D. Jones et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
survivorship analysis (3.3%). Those on the waiting list for more than 30 but less than 90 days were excluded from the 90-day analysis (33.7%). Patients undergoing bilateral procedures, either synchronous or sequential, were also excluded. All patients were seen prior to their operation in a pre-assessment clinic. At this time, an assessment of comorbidity was performed at which stage medical reasons for exclusion from surgery were identified. These included poorly controlled hypertension, diabetes, ischemic heart disease, respiratory illness and renal dysfunction. Patients for whom surgery was deemed to carry excessive risk were removed from the waiting list and therefore, were not included in either the waiting list group or the surgical group. For those in whom medical optimization was required and who were relisted for THA within the study period, only the subsequent relisting was used for the survivorship analysis. All patients were drawn from the same population. Therefore, many of the patients in the arthroplasty population were included in the waiting list population if they had been on the waiting list for 30 days or more. Following exclusion, 3621 patients in the waiting list group were available for the 30-day survivorship analysis and 2131 patients for the 90-day analysis. In the arthroplasty group, 3128 patients were available for both the 30- and 90-day survivorship analysis. Retrieval of information pertaining to death was completed as previously described [13]. Using the Demographics Batch Service through the National Health Service (NHS) Connecting for Health, the details of the two populations were traced against the national Personal Demographics Service which stores information regarding demographic characteristics of all users of the NHS within the United Kingdom (UK). It was possible to identify patients who had died within each group as well as the date of death. In each group, patients who died within 90 days either after the operation or after being listed for the operation were identified. Death certificates for these patients were retrieved from the UK General Register Office, and the cause of death was identified. In the population of patients undergoing primary THA, surgical technique was at the discretion of the operating surgeon. The method of anesthesia was at the discretion of the anesthetist. All patients received prophylactic antibiotics as per hospital protocol. The use of chemical thromboprophylaxis and intermittent pneumatic compression devices depended on the operating surgeon. All patients were fitted with graduated compression/anti-embolism stockings at the time of surgery and were advised to wear them for 6 weeks after surgery unless contraindicated. Mortality rates were calculated on the basis of cutoff points of 30 and 90 days following the date of surgery or the date of listing. Confidence intervals were calculated with the score method [15]. A chi-squared test was used to compare the proportions of patients who died between the waiting list and THA groups. Data distribution was checked with a D'Agostino and Pearson normality test. Where data were not normally distributed, central tendency is described with the median and inter-quartile ranges (IQR). Where data were normally distributed, central tendency was described with the mean and standard deviation. Normally distributed data comparison was performed with parametric tests and non-normally distributed data with non-parametric tests (Mann–Whitney test). For illustrative purposes, patients in each group were stratified according to age and the mortality rate and day-by-day mortality were calculated. A multiple regression model was used to determine if age or gender influenced the risk of death in the waiting list or THA groups at 90 days.
the mortality rate of the waiting list group was zero. The excess surgical mortality at 30 days was 0.256% (95% confidence interval: 0.130% to 0.398%); this difference was significant (P = 0.002). The 90-day mortality of patients placed on the waiting list for primary THA was 0.422% (95% confidence interval: 0.222% to 0.801%), whereas following primary THA it was 0.448% (95% confidence interval: 0.267% to 0.750%). The odds ratio was 1.06 (95% confidence interval: 0.458 to 2.453). The excess surgical mortality at 90 days was 0.025% (95% confidence interval: − 0.051% to 0.044%); this difference was not significant (P = 0.892). In the 30-day comparison the median age was 69.0 years (IQR 61.0–76.0) in those on the waiting list and 69.0 years (IQR 59.0–76.0) for those undergoing THA. In the 90-day comparison the median age was 69.0 years (IQR 61.0–76.0) in those on the waiting list and 69.0 years (IQR 59.0–76.0) for those undergoing THA. Neither of these differences was significant (P N 0.05). There was no significant difference in gender distribution in the 30-day comparison (P N 0.05; waiting list group 38.0% male, 42.0% female; THA group 38.5% male, 41.5% female) or the 90-day comparison (P N 0.05; waiting list group 36.7% male, 43.3% female; THA group 38.4% male, 41.6% female). The multiple regression model revealed that in the waiting list group at 90 days neither age (P = 0.146) nor gender (P = 0.423) influenced the risk of death. Similar findings were found in the THA group (age P = 0.307; gender P = 0.326), though the incidence of death in the over 75 years group was more common than the population under 75 years of age (0.61% versus 0.33%). The day-to-day 90-day mortality for all age groups and for those under and over the age of 75 years is shown in Figs. 1, 2 and 3. Death certificates were available for the 14 patients who died within 90 days of surgery and the 9 patients who died within 90 days of being added to the waiting list. The cause of death as detailed on the death certificate in each population is shown in Table 1. Myocardial infarction and pneumonia accounted for the majority of the postoperative deaths. Discussion The current study presents data on the incidence of death in the early post-operative period following primary THA and compares it to the incidence of death in a population of patients on the waiting list for the same period. The primary focus of this study was to identify the importance of utilizing an appropriate comparison population when identifying the increased risk of death following THA. Using the same methodology as used here, we have previously demonstrated an excess surgical mortality in association with TKR [13]. We have now
Results The 30-day mortality of patients placed on the waiting list for primary THA was 0.000% (95% confidence interval: 0.000% to 0.106%), whereas following primary THA it was 0.256% (95% confidence interval: 0.130% to 0.504%). The odds ratio could not be calculated, as
Fig. 1. Ninety-day mortality for patients undergoing primary THA compared to those remaining on the waiting list for the same procedure.
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
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Table 1 Cause of Death as Detailed on the Death Certificates of Patients Who Died Within 90 Days of Undergoing Primary Total Hip Arthroplasty or Within 90 Days of Being Added to the Waiting List for a Primary Total Hip Arthroplasty. Number of Deaths Cause of Death Bronchopneumia Acute myocardial event Multiorgan failure Metastatic carcinoma Sepsis Peritonitis secondary to perforated diverticulum Gastrointestinal hemorrhage secondary to perforated duodenal ulcer Acute myeloid leukaemia Chronic lymphocytic leukaemia Total Fig. 2. Ninety-day mortality in patients under 75 years of age undergoing primary total hip arthroplasty in comparison to those on the waiting list for the same procedure.
demonstrated a similar finding for patients undergoing primary THA, although the effect seems to be confined to the first 30 days after surgery. The 30-day mortality in the operative group in this study is comparable to that observed by others [16] but is lower than that reported elsewhere in the literature [4,7,12,17–19]. The 90-day mortality in the operative group was comparable to that demonstrated by Aynardi et al [16] and Cusick and Beverland [20] but was lower than that demonstrated by other studies [4–7,17]. The National Joint Registry for England and Wales analysis of mortality following 409,000 primary hip arthroplasties for osteoarthritis reported a secular decline in 90-day mortality from 0.6% in 2003 to 0.3% in 2011 [14]. In addition to the well-recognized decline in mortality that has resulted in an aging population, these differences may well be explained by improvements in orthopedic practice that have evolved in recent years. Improvements in anesthesia and post-operative pain management, particularly the use of hypotensive neuroaxial anesthesia techniques have greatly improved mortality from postoperative cardiorespiratory complications [21–23]. The use of both mechanical and chemical thromboprophylaxis is increasing and both are independently associated with reduced mortality [14]. Postoperative care has evolved with an increasing emphasis on early mobilization, improved analgesia and accelerated discharge. All these factors may decrease the risk of thromboembolism and pneumonia [24–26].
Fig. 3. Ninety-day mortality in patients 75 years and older undergoing primary total hip arthroplasty in comparison to those on the waiting list for the same procedure.
Arthroplasty Population
Waiting List Population
5 (36%) 5 (36%) 2 (14%) 2 (14%) 0 0 0
1 (11%) 1 (11%) 0 0 3 (33%) 1 (11%) 1 (11%)
0 0 14
1 (11%) 1 (11%) 9
Percentages are based on total number of deaths in each population.
Improvements in survival in the modern arthroplasty era may also be explained by improved pre-operative assessment of patients. The identification and optimization of significant risk factors for poor outcome following arthroplasty surgery, especially cardiovascular, respiratory and renal comorbidities, have been shown to improve mortality following surgery [27]. We have demonstrated an excess mortality at 30 days of 0.256%, but the effect was not significant at 90 days, when death in the operative group is compared to death in a comparable population awaiting the same procedure. This finding is in contrast to the often demonstrated phenomenon that patients undergoing arthroplasty procedures have improved survivorship when compared to control populations. This can be explained by looking at the control population rather than the arthroplasty population. Barrett et al [5] demonstrated an improved survivorship at 90 days when comparing patients undergoing primary hip arthroplasty with a sample of the general population. Lie et al [4] found a similar outcome when comparing long-term survivorship following THA with the general population at 8 years following surgery. Indeed, when using alternative measures such as standardized mortality ratios or age controls, the effect remains [11,12]. This can be explained by the “well” patient effect whereby patients are denied elective surgery if they are deemed to be medically unfit, thereby selecting a surgical cohort with better health than the general population. The cause of death in the arthroplasty population in this study is in keeping with those described by others with the majority of deaths resulting from cardiac events or bronchopneumonia [17]. In comparison, the distribution of causes of death in the waiting list group was much more diverse. These included perforation of viscus and sepsis, which would not have been identified on pre-operative assessment. Of note, fatal pulmonary embolus did not feature as a cause of death in the arthroplasty population. This is in contrast to the previously reported incidence of fatal embolic events following lower limb arthroplasty [28–30] and suggests that fatal pulmonary embolus is a rare event following primary THA. An extremely low incidence of fatal pulmonary embolus following THA has previously been reported [20,31]. Patents in the arthroplasty population of this study did not receive a standardized thromboprophylaxis regimen but all received both mechanical and chemical thromboprophylaxis, so conclusions about the efficacy or otherwise of any particular pharmacological or mechanical intervention, cannot be made. Rather, suffice to say, in the modern era, a combination of factors have combined to reduced fatal thrombotic events following elective THA to a rare occurrence. Using a multivariate analysis model, we have demonstrated no significant effect of either age or gender on the incidence of death at 90 days between the arthroplasty and waiting list populations. However, death in the operated group was more common in the more elderly population. Increasing age and male gender are well
Please cite this article as: Jones MD, et al, Early Death Following Primary Total Hip Arthroplasty, J Arthroplasty (2014), http://dx.doi.org/ 10.1016/j.arth.2014.02.002
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known to be associated with increased post-operative mortality [4,12,14,17,32], but our sample size was probably too small to demonstrate this. In summary, by using an appropriate control population, we have demonstrated that THA is associated with a significant excess surgical mortality at 30 days post-operation, but this effect diminishes by 90 days. Patients should be counseled accurately about the magnitude of this risk and efforts to decrease mortality should concentrate on the early post-operative period. Acknowledgments No further authors or contributors other than those stated were involved in the execution or preparation of this manuscript. No sources of funding were required for the execution or preparation of this manuscript. No sponsors were required for this study and none of the authors were involved with funding sources or sponsors for the execution of this study. Ethical approval was not required for this study. References 1. Ethgen O, Bruyère O, Richy F, et al. Health-related quality of life in total hip and total knee arthroplasty: a qualitative and systematic review of the literature. J Bone Joint Surg Am 2004;86(5):963. 2. Daigle ME, Weinstein AM, Katz JN, et al. The cost-effectiveness of total joint arthroplasty: a systematic review of the literature. Best Pract Res Clin Rheumatol 2012;26(5):649. 3. Chang RW. A cost-effectiveness analysis of total hip arthroplasty for osteoarthritis of the hip. JAMA 1996;275(11):858. 4. Lie SA, Engesaeter LB, Havelin LI, et al. Mortality after total hip replacement: 0–10year follow-up of 39,543 patients in the Norwegian Arthroplasty Register. Acta Orthop 2000;71(1):19. 5. Barrett J, Losina E, Baron JA, et al. Survival following total hip replacement. J Bone Joint Surg Am 2005;87(9):1965. 6. Mahomed NN, Barrett JA, Katz JN, et al. Rates and outcomes of primary and revision total hip replacement in the United States Medicare Population. J Bone Joint Surg Am 2003;85(1):27. 7. Pedersen AB, Baron JA, Overgaard S, et al. Short- and long-term mortality following primary total hip replacement for osteoarthritis: a Danish nationwide epidemiological study. J Bone and Joint Surgery Br 2011;93-B(2):172. 8. Holmberg S. Life expectancy after total hip arthroplasty. J Arthroplasty 1992 Jun;7(2):183. 9. Visuri T, Pulkkinen P, Turula KB, et al. Life expectancy after hip arthroplasty: case– control study of 1018 cases of primary arthrosis. Acta Orthop Scand 1994;65(1):9. 10. Garellick G, Malchau H, Herberts P, et al. Life expectancy and cost utility after total hip replacement. Clin Orthop Relat Res 1998;346:141. 11. Paavolainen P, Pukkala E, Pulkkinen P, et al. Causes of death after total hip arthroplasty. J Arthroplasty 2002;17(3):274.
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