Number needed to treat in COPD: exacerbations versus pneumonias
- PMID: 23125170
- DOI: 10.1136/thoraxjnl-2012-202709
Number needed to treat in COPD: exacerbations versus pneumonias
Abstract
Background: Several recent trials in chronic obstructive pulmonary disease (COPD) have assessed the effectiveness of the fluticasone-salmeterol combination inhaler in preventing COPD exacerbations, while finding an increased risk of pneumonia. The number needed to treat (NNT) is a simple measure to perform the comparative benefit-risk impact, but its calculation involving repeated outcome events such as COPD exacerbations has been incorrect. We describe the proper methods to calculate the NNT and, using data from published trials, apply them to evaluate the relative impact of fluticasone-salmeterol treatment on exacerbations and pneumonias in patients with COPD.
Methods: We review the fundamental definition of NNT and quantify it for situations with varying follow-up times. We review the 'event-based' NNT, proposed and used for repeated event outcomes, show its inaccuracy, describe its proper use and provide an approximate formula for its application.
Results: We show that a 1-year trial of the fluticasone-salmeterol combination versus salmeterol used the incorrect event-based approach to calculate the NNT as two patients that need to be treated for 1 year to prevent one COPD exacerbation, when the proper calculation results in a NNT of 14. In contrast, 20 patients need to be treated to induce one pneumonia case. For the TORCH trial, the NNT is 44 patients treated for 3 years with fluticasone-salmeterol versus salmeterol to prevent one exacerbation compared with 16 patients to induce one pneumonia case.
Conclusions: The NNT is a useful measure of the effect of drugs, but its proper calculation is essential to prevent misleading clinical practice guidelines.
Comment in
-
Number needed to treat in COPD: exacerbations versus pneumonias.Thorax. 2013 Sep;68(9):882. doi: 10.1136/thoraxjnl-2013-203403. Epub 2013 Mar 15. Thorax. 2013. PMID: 23503625 No abstract available.
-
Author's response to letter on number needed to treat in COPD: exacerbations versus pneumonias.Thorax. 2013 Sep;68(9):882-3. doi: 10.1136/thoraxjnl-2013-203461. Epub 2013 Mar 22. Thorax. 2013. PMID: 23935172 No abstract available.
Similar articles
-
Salmeterol and fluticasone propionate and survival in chronic obstructive pulmonary disease.N Engl J Med. 2007 Feb 22;356(8):775-89. doi: 10.1056/NEJMoa063070. N Engl J Med. 2007. PMID: 17314337 Clinical Trial.
-
Relative effectiveness of budesonide/formoterol and fluticasone propionate/salmeterol in a 1-year, population-based, matched cohort study of patients with chronic obstructive pulmonary disease (COPD): Effect on COPD-related exacerbations, emergency department visits and hospitalizations, medication utilization, and treatment adherence.Clin Ther. 2010 Jul;32(7):1320-8. doi: 10.1016/j.clinthera.2010.06.022. Clin Ther. 2010. PMID: 20678680
-
Tiotropium versus salmeterol for the prevention of exacerbations of COPD.N Engl J Med. 2011 Mar 24;364(12):1093-1103. doi: 10.1056/NEJMoa1008378. N Engl J Med. 2011. PMID: 21428765 Clinical Trial.
-
Evaluating the effectiveness of combination therapy to prevent COPD exacerbations: the value of NNT analysis.Int J Clin Pract. 2005 Oct;59(10):1187-94. doi: 10.1111/j.1368-5031.2005.00664.x. Int J Clin Pract. 2005. PMID: 16178987 Review.
-
Methodological issues in therapeutic trials of COPD.Eur Respir J. 2008 May;31(5):927-33. doi: 10.1183/09031936.00098307. Epub 2008 Jan 23. Eur Respir J. 2008. PMID: 18216056 Review.
Cited by
-
Efficacy of a self-management plan in exacerbations for patients with advanced COPD.Int J Chron Obstruct Pulmon Dis. 2016 Aug 17;11:1939-47. doi: 10.2147/COPD.S104728. eCollection 2016. Int J Chron Obstruct Pulmon Dis. 2016. PMID: 27574418 Free PMC article. Clinical Trial.
-
Comparative effectiveness of triple therapy versus dual bronchodilation in COPD.ERJ Open Res. 2019 Aug 30;5(3):00106-2019. doi: 10.1183/23120541.00106-2019. eCollection 2019 Jul. ERJ Open Res. 2019. PMID: 31497610 Free PMC article.
-
Withdrawal of inhaled corticosteroids can be safe in COPD patients at low risk of exacerbation: a real-life study on the appropriateness of treatment in moderate COPD patients (OPTIMO).Respir Res. 2014 Jul 8;15(1):77. doi: 10.1186/1465-9921-15-77. Respir Res. 2014. PMID: 25005873 Free PMC article.
-
Inhaled corticosteroids and the increased risk of pneumonia: what's new? A 2015 updated review.Ther Adv Respir Dis. 2016 Jun;10(3):235-55. doi: 10.1177/1753465816630208. Epub 2016 Feb 18. Ther Adv Respir Dis. 2016. PMID: 26893311 Free PMC article. Review.
-
Drugs for chronic obstructive pulmonary disease.Aust Prescr. 2017 Feb;40(1):15-19. doi: 10.18773/austprescr.2017.003. Epub 2017 Feb 1. Aust Prescr. 2017. PMID: 28246430 Free PMC article. Review. No abstract available.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Medical
