Quality of randomised trials in chronic obstructive pulmonary disease

¹ Horten Centre for patient-oriented research and knowledge transfer, University of Zurich, Switzerland
² Kleijnen Systematic Reviews Ltd, York, United Kingdom. jos@sytematic-reviews.com; and Care and Public Health Research Institute (CAPHRI), University of Maastricht, The Netherlands
³ Horten Centre for patient-oriented research and knowledge transfer, University of Zurich, Switzerland; and Dept of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore (MD), USA

^* To whom correspondence should be addressed. E-mail: mpuhan{at}jhsph.edu.

	Abstract

Randomised trials can provide high-level evidence to inform treatment decisions. Since their quality in respiratory medicine is largely unknown, we assessed the quality of a large set of COPD trials.

As a marker of trial quality we assessed the procedure and concealment of random allocation and the conduct of an intention-to-treat-analysis in 344 randomised trials published between 1957 and 2006. We used ordered logistic regression to assess the association between trial quality and type of intervention, type of journal, impact factor, and years of publication.

257 (75%) trials assessed pharmacological and 87 (25%) non-pharmacological interventions. The generation of an appropriate randomisation was reported in 27.0% of the trials, concealment of random allocation in 11.6% and an intention-to-treat analysis in 21.8% of trials, respectively. Significantly higher quality was found in trials on non-pharmacological interventions (odds ratio 2.49 [95% 1.56–3.99]), when published in general medical (versus specialised) journals (2.25 [1.30–3.90]) and after 2000 (versus 1957 to 2000, 2.28 [1.45–3.58]). The association of quality with a high impact factor was of borderline significance (p=0.06).

The quality of many COPD trials is low but tends to become better since the adoption of the CONSORT statement.