Downloaded from http://thorax.bmj.com/ on June 24, 2015 - Published by group.bmj.com
PostScript
CORRESPONDENCE
Subacute bronchial toxicity induced by an electronic cigarette: take home message The case-based discussion of an adult smoker with respiratory symptoms and worsened pulmonary function shortly after switching to an electronic cigarette (e-cig)1 can be interpreted differently. Ironically, some people experience transient (days/weeks) worsening of respiratory symptoms (cough, wheezing, chest tightness) after quitting.2 Cough and breathlessness have been reported when switching to e-cigs, but progressive improvement in respiratory symptoms is usually observed with regular use of these products.3 Significant risk reduction and harm reversal are expected in smokers who switch from tobacco to e-cigs.3 4 Signs and symptoms compatible with contact dermatitis around the mouth or in the oral mucosa may occur in predisposed e-cig users exposed to propylene glycol (PG) in the vapour,5 but the e-liquid used by this patient contained glycerol, not PG. Hypersensitivity response to glycerol has never been reported to our knowledge. Consequently, performing skin prick testing with a product that does not contain PG and is not approved for this indication is of questionable utility and safety. Additionally, the authors’ reference to ethylene glycol and mineral oil is irrelevant since these ingredients are not normally present in e-liquids and are not in the GRAS generally regarded as safe list. Alternatively, some unknown contaminants/by-products in the e-cig vapour might have been responsible for this patient’s symptoms. The observation that the patient has moderate COPD recovering from a right upper lobe resection together with the lack of lung function results at earlier time points after lung surgery complicates the interpretation of the pulmonary function test findings in relation to e-cig use. Riccardo Polosa,1,2 Davide Campagna,1,2 Donald Tashkin3 Teaching Hospital ‘Policlinico-Vittorio Emanuele’, Centro per la Prevenzione e Cura del Tabagismo (CPCT), Catania, Italy 2 Teaching Hospital ‘Policlinico-Vittorio Emanuele’, Institute of Internal and Emergency Medicine, Catania, Italy 3 UCLA University of California, David Geffen School of Medicine, Los Angeles, California, USA
Contributors RP had the idea of sketching a response article, but all authors contributed in equal parts to the reporting and writing up. All authors have read and approved the final manuscript. RP is responsible for the overall content as guarantor. Competing interests RP has received lecture fees from Pfizer and GSK, a research grant from Pfizer, and he served as a consultant for Pfizer, Global Health Alliance for treatment of tobacco dependence and Arbi Group Srl (the Italian distributor for Categoria electronic cigarettes). Provenance and peer review Not commissioned; internally peer reviewed.
To cite Polosa R, Campagna D, Tashkin D. Thorax 2014;69:588. Received 4 February 2014 Revised 25 March 2014 Accepted 26 March 2014 Published Online First 12 April 2014
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204767 Thorax 2014;69:588. doi:10.1136/thoraxjnl-2014-205230
REFERENCES 1
2
3
4
5
Hureaux J, Drouet M, Urban T. A case report of subacute bronchial toxicity induced by an electronic cigarette. Thorax 2014;69:596–7. Cummings KM, Giovino G, Jaen CR, et al. Reports of smoking withdrawal symptoms over a 21-day period of abstinence. Addict Behav 1985;10:373–81. Caponnetto P, Campagna D, Cibella F, et al. Efficiency and safety of an electronic cigarette (ECLAT) as tobacco cigarettes substitute: a prospective 12-month randomized control design study. PLoS One 2013;8: e66317. Farsalinos KE, Polosa R. Safety evaluation and risk assessment of electronic cigarettes as tobacco cigarettes substitutes: a systematic review. Ther Adv Drug Safety 2014;2:67–86. Hua M, Alfi M, Talbot P. Health-related effects reported by electronic cigarette users in online forums. J Med Internet Res 2013;15:e59.
Primary healthcare factors and hospital admission rates for COPD: no association
1
Correspondence to Professor Riccardo Polosa, AOU Policlinico-V. Emanuele, Via S. Sofia, 78, Catania 95123, Italy; [email protected] 588
As the ‘observant researchers’ who questioned the R2 value reported by Calderón-Larrañaga et al we were disappointed by the correction in Thorax, 10 July 2013.1 2 Our concerns were raised by the high adjusted R2 value of 0.75 in the multivariate linear regression of the association of primary care trust (PCT) factors with PCT hospital admission rates and the
high bivariate R2 value attributed to general practitioner (GP) supply. The authors pointed out to us their misreading of the bivariate ‘GP supply’ R2 of 0.14% which led to the error. We were surprised to read in their correction that the R2 value of 14.4% was for the variable ‘GP list size’. In the data they sent to us this variable R2 had been recorded as 17%. GP list size was not reported in the bivariate or multivariate analyses in the paper. This is worthy of comment. Adjustment for PCT practice list size was already included in the dependent variable which was COPD admissions/ 100 000 GP registered population. This newly reported finding suggests that a large proportion of the variance (bivariate) in hospital admission rates at PCT level was explained independently by GP list size. Calderón-Larrañaga et al reported PCT GPs/100 000 patients to have had a multivariate regression coefficient of 0.995 (95% CI 0.992 to 1.00) with respect to hospital admissions. While not statistically significant, even with an upper 95% CI limit of 0.995 the effect size would have been so small that the predictive power of the number of GPs/100 000 would have been irrelevant in practice. In their Poisson regression of GP-based factors on hospital admission count, the effect of practice GPs/100 000 patients had an incidence rate ratio of 0.998 (95% CI 0.998 to 0.999). This is harder to interpret. The dependent variable was the count of COPD admissions/practice in any year of 3 years. The predictor variable, the number of GPs/100 000 population at practice level, is also hard to interpret. Its mean was 60 with an IQR between 10 and 180. This suggests that in the bottom 25% of practices there was less than 1 GP per 10 000 patients, with more than 1 GP per 550 patients in the top 25%. The IQR for GPs/100 000 population derived from data for all general practices in England from the General Medical Services database and based on practice data submitted on 31 March 2007 was 46.94–71.39, a range more in keeping with observed practice.3 The effect size of GPs/100 000 population in the Poisson regression of practice level data, expressed as the incidence rate ratio, was tiny and perhaps statistically significant because the analysis was based on more than 8000 general practices. Our conclusion is that GP supply was not predictive of COPD admission rates. COPD and COPD admissions are more prevalent in deprived populations because rates of smoking are higher. There is no Thorax June 2014 Vol 69 No 6
Downloaded from http://thorax.bmj.com/ on June 24, 2015 - Published by group.bmj.com
PostScript evidence that GP supply or treatment factors are predictive of rates of COPD admissions at practice or PCT level. All of this suggests that the claim in the editorial published alongside this paper that the inverse care law is alive and well with respect to hospital admission rates for COPD needs to be reconsidered.4 Patrick White, Ana Lucia Jamieson Division of Health and Social Care Research, Department of Primary Care and Public Health Sciences, King’s College London, King’s Health Partners, London, UK Correspondence to Dr Patrick White, Division of Health and Social Care Research, Department of Primary Care and Public Health Sciences, King’s College London, 9th Floor Capital House, Weston Street, London SE1 3QD, UK; [email protected] Contributors PW conceived the correspondence and drafted the letter. ALJ drafted the letter. Competing interests None. Provenance and peer review Not commissioned; externally peer reviewed.
To cite White P, Jamieson AL. Thorax 2014;69:588– 589. Received 19 July 2013 Revised 5 November 2013 Accepted 7 November 2013 Published Online First 22 November 2013
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204798 ▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204807
science with eagle-eyed scrutiny by readers. Calderon-Larrañaga et al highlighted the important association of deprivation with hospital admission rates and asserted that markers of primary care quality, such as GP supply, were lower in deprived areas. Dr White makes some valid points when questioning the data suggesting that the quality of services in areas of deprivation is inferior. Having written the accompanying editorial3 to the paper by CalderonLarrañaga et al, I accept that the evidence underpinning the inverse care law is now subject to debate. Whether or not primary care services are better or worse in deprived areas, what is not is debate is that deprivation is the nursery of many chronic diseases, including COPD, vasculopathies and cancer.4 The theme of the editorial remains sound: investment in primary care services in areas of deprivation is needed if we are going to improve management of long-term conditions and reduce the impact on stretched hospitals and stretched commissioning budgets. Effective strategies linking health, social care and education in our deprived populations are needed to address the roots of this modern non-communicable plague. Rupert Jones Correspondence to Dr Rupert Jones, Plymouth University Peninsula School of Medicine and Dentistry, 1 Davy Rd (N21), Plymouth P6 8BX, UK; [email protected], [email protected] Competing interests None. Provenance and peer review Not commissioned; internally peer reviewed.
Thorax 2014;69:588–589. doi:10.1136/thoraxjnl-2013-204215
REFERENCES 1
2 3 4
Calderón-Larrañaga A, Carney L, Soljak M, et al. Association of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease in England: national cross-sectional study. Thorax 2011;66:191–6. Calderón-Larrañaga A, Carney L, Soljak M, et al. Correction. Thorax 2013;68:781. Health and Social Care Information Centre, Leeds. http://www.ic.nhs.uk/ Jones RCM. Hospital admission rates for COPD: the inverse care law is alive and well. Thorax 2011;66:185–6.
Primary healthcare factors and hospital admission rates for COPD Dr White’s interesting observations1 on the paper by Calderon-Larrañaga et al2 show the real benefit of peer-reviewed
Thorax June 2014 Vol 69 No 6
To cite Jones R. Thorax 2014;69:589. Accepted 8 November 2013 Published Online First 28 November 2013
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204215 ▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204807 Thorax 2014;69:589. doi:10.1136/thoraxjnl-2013-204798
REFERENCES 1
2
White P, Jamieson AL. Primary healthcare factors and hospital admission rates for COPD: no association. Thorax 2014;69:588–9. Calderon-Larranaga A, Carney L, Soljak M, et al. Association of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease in England:
3 4
national cross-sectional study. Thorax 2011;66: 191–6. Jones RC. Hospital admission rates for COPD: the inverse care law is alive and well. Thorax 2011;66:185–6. Barnett K, Mercer SW, Norbury M, et al. Epidemiology of multimorbidity and implications for health care, research, and medical education: a cross-sectional study. Lancet 2012;380:37–43.
Authors’ response to: primary healthcare factors and hospital admission rates for COPD: no association We thank White and Jamieson for their comments1 on our 2011 Thorax paper on associations with admission rates for COPD.2 White and Jamieson appear to be confused about the practice population measures we used. If that is because we referred to the variable concerned too loosely in our correspondence with them we apologise. However as table 4 of our paper demonstrates, the only general practitioner (GP) supply variable used in the analysis, at either primary care trust or practice levels, was GPs/100 000 practice population. We do not agree with their statement that COPD admissions/100 000 GP-registered population includes an adjustment for practice list size, as it is purely a measure of the incidence rate in a population. We included practice list size (which is not a measure of supply) as an independent variable, but it was later dropped in the multivariable analysis stepwise variable selection. We agree with White and Jamieson that the effect size of GPs/100 000 population is small compared with the much larger effects of other population and healthcare factors in the paper. However White and Jamieson then go on to make the sweeping and unjustified statement that “there is no evidence that GP supply or treatment factors are predictive of rates of COPD admissions”. Our COPD analysis shows that patient-perceived access to primary healthcare—Quality & Outcomes Framework (QOF) Patient Experience indicators 07 and 08—has a large effect size, with incidence rate ratios (IRRs) of 0.790 and 0.902, respectively, as does influenza immunisation (QOF COPD indicator 8, IRR 0.825). Surely these are primary healthcare factors? It is plausible that actual or perceived poor access to primary care could delay treatment for COPD exacerbations. Simulation modelling suggests that the best strategy to reduce the burden of COPD is by reducing exacerbations, and our analysis provides evidence for that.3
589
Downloaded from http://thorax.bmj.com/ on June 24, 2015 - Published by group.bmj.com
Primary healthcare factors and hospital admission rates for COPD: no association Patrick White and Ana Lucia Jamieson Thorax 2014 69: 588-589 originally published online November 22, 2013
doi: 10.1136/thoraxjnl-2013-204215 Updated information and services can be found at: http://thorax.bmj.com/content/69/6/588.1
These include:
References Email alerting service
This article cites 3 articles, 3 of which you can access for free at: http://thorax.bmj.com/content/69/6/588.1#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
PostScript
CORRESPONDENCE
Subacute bronchial toxicity induced by an electronic cigarette: take home message The case-based discussion of an adult smoker with respiratory symptoms and worsened pulmonary function shortly after switching to an electronic cigarette (e-cig)1 can be interpreted differently. Ironically, some people experience transient (days/weeks) worsening of respiratory symptoms (cough, wheezing, chest tightness) after quitting.2 Cough and breathlessness have been reported when switching to e-cigs, but progressive improvement in respiratory symptoms is usually observed with regular use of these products.3 Significant risk reduction and harm reversal are expected in smokers who switch from tobacco to e-cigs.3 4 Signs and symptoms compatible with contact dermatitis around the mouth or in the oral mucosa may occur in predisposed e-cig users exposed to propylene glycol (PG) in the vapour,5 but the e-liquid used by this patient contained glycerol, not PG. Hypersensitivity response to glycerol has never been reported to our knowledge. Consequently, performing skin prick testing with a product that does not contain PG and is not approved for this indication is of questionable utility and safety. Additionally, the authors’ reference to ethylene glycol and mineral oil is irrelevant since these ingredients are not normally present in e-liquids and are not in the GRAS generally regarded as safe list. Alternatively, some unknown contaminants/by-products in the e-cig vapour might have been responsible for this patient’s symptoms. The observation that the patient has moderate COPD recovering from a right upper lobe resection together with the lack of lung function results at earlier time points after lung surgery complicates the interpretation of the pulmonary function test findings in relation to e-cig use. Riccardo Polosa,1,2 Davide Campagna,1,2 Donald Tashkin3 Teaching Hospital ‘Policlinico-Vittorio Emanuele’, Centro per la Prevenzione e Cura del Tabagismo (CPCT), Catania, Italy 2 Teaching Hospital ‘Policlinico-Vittorio Emanuele’, Institute of Internal and Emergency Medicine, Catania, Italy 3 UCLA University of California, David Geffen School of Medicine, Los Angeles, California, USA
Contributors RP had the idea of sketching a response article, but all authors contributed in equal parts to the reporting and writing up. All authors have read and approved the final manuscript. RP is responsible for the overall content as guarantor. Competing interests RP has received lecture fees from Pfizer and GSK, a research grant from Pfizer, and he served as a consultant for Pfizer, Global Health Alliance for treatment of tobacco dependence and Arbi Group Srl (the Italian distributor for Categoria electronic cigarettes). Provenance and peer review Not commissioned; internally peer reviewed.
To cite Polosa R, Campagna D, Tashkin D. Thorax 2014;69:588. Received 4 February 2014 Revised 25 March 2014 Accepted 26 March 2014 Published Online First 12 April 2014
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204767 Thorax 2014;69:588. doi:10.1136/thoraxjnl-2014-205230
REFERENCES 1
2
3
4
5
Hureaux J, Drouet M, Urban T. A case report of subacute bronchial toxicity induced by an electronic cigarette. Thorax 2014;69:596–7. Cummings KM, Giovino G, Jaen CR, et al. Reports of smoking withdrawal symptoms over a 21-day period of abstinence. Addict Behav 1985;10:373–81. Caponnetto P, Campagna D, Cibella F, et al. Efficiency and safety of an electronic cigarette (ECLAT) as tobacco cigarettes substitute: a prospective 12-month randomized control design study. PLoS One 2013;8: e66317. Farsalinos KE, Polosa R. Safety evaluation and risk assessment of electronic cigarettes as tobacco cigarettes substitutes: a systematic review. Ther Adv Drug Safety 2014;2:67–86. Hua M, Alfi M, Talbot P. Health-related effects reported by electronic cigarette users in online forums. J Med Internet Res 2013;15:e59.
Primary healthcare factors and hospital admission rates for COPD: no association
1
Correspondence to Professor Riccardo Polosa, AOU Policlinico-V. Emanuele, Via S. Sofia, 78, Catania 95123, Italy; [email protected] 588
As the ‘observant researchers’ who questioned the R2 value reported by Calderón-Larrañaga et al we were disappointed by the correction in Thorax, 10 July 2013.1 2 Our concerns were raised by the high adjusted R2 value of 0.75 in the multivariate linear regression of the association of primary care trust (PCT) factors with PCT hospital admission rates and the
high bivariate R2 value attributed to general practitioner (GP) supply. The authors pointed out to us their misreading of the bivariate ‘GP supply’ R2 of 0.14% which led to the error. We were surprised to read in their correction that the R2 value of 14.4% was for the variable ‘GP list size’. In the data they sent to us this variable R2 had been recorded as 17%. GP list size was not reported in the bivariate or multivariate analyses in the paper. This is worthy of comment. Adjustment for PCT practice list size was already included in the dependent variable which was COPD admissions/ 100 000 GP registered population. This newly reported finding suggests that a large proportion of the variance (bivariate) in hospital admission rates at PCT level was explained independently by GP list size. Calderón-Larrañaga et al reported PCT GPs/100 000 patients to have had a multivariate regression coefficient of 0.995 (95% CI 0.992 to 1.00) with respect to hospital admissions. While not statistically significant, even with an upper 95% CI limit of 0.995 the effect size would have been so small that the predictive power of the number of GPs/100 000 would have been irrelevant in practice. In their Poisson regression of GP-based factors on hospital admission count, the effect of practice GPs/100 000 patients had an incidence rate ratio of 0.998 (95% CI 0.998 to 0.999). This is harder to interpret. The dependent variable was the count of COPD admissions/practice in any year of 3 years. The predictor variable, the number of GPs/100 000 population at practice level, is also hard to interpret. Its mean was 60 with an IQR between 10 and 180. This suggests that in the bottom 25% of practices there was less than 1 GP per 10 000 patients, with more than 1 GP per 550 patients in the top 25%. The IQR for GPs/100 000 population derived from data for all general practices in England from the General Medical Services database and based on practice data submitted on 31 March 2007 was 46.94–71.39, a range more in keeping with observed practice.3 The effect size of GPs/100 000 population in the Poisson regression of practice level data, expressed as the incidence rate ratio, was tiny and perhaps statistically significant because the analysis was based on more than 8000 general practices. Our conclusion is that GP supply was not predictive of COPD admission rates. COPD and COPD admissions are more prevalent in deprived populations because rates of smoking are higher. There is no Thorax June 2014 Vol 69 No 6
Downloaded from http://thorax.bmj.com/ on June 24, 2015 - Published by group.bmj.com
PostScript evidence that GP supply or treatment factors are predictive of rates of COPD admissions at practice or PCT level. All of this suggests that the claim in the editorial published alongside this paper that the inverse care law is alive and well with respect to hospital admission rates for COPD needs to be reconsidered.4 Patrick White, Ana Lucia Jamieson Division of Health and Social Care Research, Department of Primary Care and Public Health Sciences, King’s College London, King’s Health Partners, London, UK Correspondence to Dr Patrick White, Division of Health and Social Care Research, Department of Primary Care and Public Health Sciences, King’s College London, 9th Floor Capital House, Weston Street, London SE1 3QD, UK; [email protected] Contributors PW conceived the correspondence and drafted the letter. ALJ drafted the letter. Competing interests None. Provenance and peer review Not commissioned; externally peer reviewed.
To cite White P, Jamieson AL. Thorax 2014;69:588– 589. Received 19 July 2013 Revised 5 November 2013 Accepted 7 November 2013 Published Online First 22 November 2013
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204798 ▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204807
science with eagle-eyed scrutiny by readers. Calderon-Larrañaga et al highlighted the important association of deprivation with hospital admission rates and asserted that markers of primary care quality, such as GP supply, were lower in deprived areas. Dr White makes some valid points when questioning the data suggesting that the quality of services in areas of deprivation is inferior. Having written the accompanying editorial3 to the paper by CalderonLarrañaga et al, I accept that the evidence underpinning the inverse care law is now subject to debate. Whether or not primary care services are better or worse in deprived areas, what is not is debate is that deprivation is the nursery of many chronic diseases, including COPD, vasculopathies and cancer.4 The theme of the editorial remains sound: investment in primary care services in areas of deprivation is needed if we are going to improve management of long-term conditions and reduce the impact on stretched hospitals and stretched commissioning budgets. Effective strategies linking health, social care and education in our deprived populations are needed to address the roots of this modern non-communicable plague. Rupert Jones Correspondence to Dr Rupert Jones, Plymouth University Peninsula School of Medicine and Dentistry, 1 Davy Rd (N21), Plymouth P6 8BX, UK; [email protected], [email protected] Competing interests None. Provenance and peer review Not commissioned; internally peer reviewed.
Thorax 2014;69:588–589. doi:10.1136/thoraxjnl-2013-204215
REFERENCES 1
2 3 4
Calderón-Larrañaga A, Carney L, Soljak M, et al. Association of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease in England: national cross-sectional study. Thorax 2011;66:191–6. Calderón-Larrañaga A, Carney L, Soljak M, et al. Correction. Thorax 2013;68:781. Health and Social Care Information Centre, Leeds. http://www.ic.nhs.uk/ Jones RCM. Hospital admission rates for COPD: the inverse care law is alive and well. Thorax 2011;66:185–6.
Primary healthcare factors and hospital admission rates for COPD Dr White’s interesting observations1 on the paper by Calderon-Larrañaga et al2 show the real benefit of peer-reviewed
Thorax June 2014 Vol 69 No 6
To cite Jones R. Thorax 2014;69:589. Accepted 8 November 2013 Published Online First 28 November 2013
▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204215 ▸ http://dx.doi.org/10.1136/thoraxjnl-2013-204807 Thorax 2014;69:589. doi:10.1136/thoraxjnl-2013-204798
REFERENCES 1
2
White P, Jamieson AL. Primary healthcare factors and hospital admission rates for COPD: no association. Thorax 2014;69:588–9. Calderon-Larranaga A, Carney L, Soljak M, et al. Association of population and primary healthcare factors with hospital admission rates for chronic obstructive pulmonary disease in England:
3 4
national cross-sectional study. Thorax 2011;66: 191–6. Jones RC. Hospital admission rates for COPD: the inverse care law is alive and well. Thorax 2011;66:185–6. Barnett K, Mercer SW, Norbury M, et al. Epidemiology of multimorbidity and implications for health care, research, and medical education: a cross-sectional study. Lancet 2012;380:37–43.
Authors’ response to: primary healthcare factors and hospital admission rates for COPD: no association We thank White and Jamieson for their comments1 on our 2011 Thorax paper on associations with admission rates for COPD.2 White and Jamieson appear to be confused about the practice population measures we used. If that is because we referred to the variable concerned too loosely in our correspondence with them we apologise. However as table 4 of our paper demonstrates, the only general practitioner (GP) supply variable used in the analysis, at either primary care trust or practice levels, was GPs/100 000 practice population. We do not agree with their statement that COPD admissions/100 000 GP-registered population includes an adjustment for practice list size, as it is purely a measure of the incidence rate in a population. We included practice list size (which is not a measure of supply) as an independent variable, but it was later dropped in the multivariable analysis stepwise variable selection. We agree with White and Jamieson that the effect size of GPs/100 000 population is small compared with the much larger effects of other population and healthcare factors in the paper. However White and Jamieson then go on to make the sweeping and unjustified statement that “there is no evidence that GP supply or treatment factors are predictive of rates of COPD admissions”. Our COPD analysis shows that patient-perceived access to primary healthcare—Quality & Outcomes Framework (QOF) Patient Experience indicators 07 and 08—has a large effect size, with incidence rate ratios (IRRs) of 0.790 and 0.902, respectively, as does influenza immunisation (QOF COPD indicator 8, IRR 0.825). Surely these are primary healthcare factors? It is plausible that actual or perceived poor access to primary care could delay treatment for COPD exacerbations. Simulation modelling suggests that the best strategy to reduce the burden of COPD is by reducing exacerbations, and our analysis provides evidence for that.3
589
Downloaded from http://thorax.bmj.com/ on June 24, 2015 - Published by group.bmj.com
Primary healthcare factors and hospital admission rates for COPD: no association Patrick White and Ana Lucia Jamieson Thorax 2014 69: 588-589 originally published online November 22, 2013
doi: 10.1136/thoraxjnl-2013-204215 Updated information and services can be found at: http://thorax.bmj.com/content/69/6/588.1
These include:
References Email alerting service
This article cites 3 articles, 3 of which you can access for free at: http://thorax.bmj.com/content/69/6/588.1#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
