Article type
Year
Abstract
Background: Several meta-epidemiological studies have examined the relationship between aspects of methodological quality of randomised controlled trials (RCTs) and bias in meta-analyses. With the development both of increased awareness of potential biases, and of reporting protocols (such as the CONSORT statement(1;2)), the quality and reporting of RCTs included in systematic reviews should have improved over time. We have created a database of meta-epidemiological studies which will be used to perform analysis of associations between trial characteristics and treatment effects, and will also allow examination of characteristics of RCTs over time
Objectives: To describe temporal changes in characteristics of RCTs included in systematic reviews.
Methods: Data were combined in an Access database. Unique identifiers were assigned for each trial using the identification number assigned by cataloguing databases, and duplicate references were identified. Year of publication was grouped to give approximately equal-sized groups.
Results: Publication dates, where given, of the 2950 unique RCTs ranged from 1950 to 2000. Three of the meta-epidemiological studies (3-5) (1679 RCTs from 184 meta-analyses) contained information about allocation concealment. In 391 (23%) RCTs, allocation concealment was considered adequate while in 950 (57%) it was unclear; in 338 (20%) it was inadequate. Over time, the proportion of RCTs in which reported allocation concealment was adequate remained approximately constant until 1995, after which it increased to 32% (Table1). Following the publication of the CONSORT statement the proportion of RCTs with adequate reported allocation concealment increased to 44%. Conclusions: In this group of RCTs included in meta-epidemiological studies, the proportion with adequate allocation concealment has improved since the mid 1990s. Publication of the CONSORT statement may have reinforced this improvement in trial quality.
(1) Begg C, Cho M, Eastwood S, Horton R, Moher D, Olkin I et al. Improving the Quality of Reporting of Randomized Controlled Trials - The Consort Statement. JAMA 1996; 276(8):637-639. (2) Altman DG, Schulz KF, Moher D, Egger M, Davidoff F, Elbourne D et al. The revised CONSORT statement for reporting randomized trials: Explanation and elaboration. Annals of Internal Medicine 2001; 134:663-694. (3) Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias - Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. Journal of the American Medical Association 1995; 273(5):408-412. (4) Jüni P, Holenstein F, Sterne J, Bartlett C, Egger M. Direction and impact of language bias in meta-analyses of controlled trials: empirical study . International Journal of Epidemiology 2002; in press. (5) Royle P, Milne R. Literature searching for randomised controlled trials used in Cochrane reviews: rapid versus exhaustive searches. International Journal of Technology Assessment in Health Care 2003; 19(4):1-13.
Objectives: To describe temporal changes in characteristics of RCTs included in systematic reviews.
Methods: Data were combined in an Access database. Unique identifiers were assigned for each trial using the identification number assigned by cataloguing databases, and duplicate references were identified. Year of publication was grouped to give approximately equal-sized groups.
Results: Publication dates, where given, of the 2950 unique RCTs ranged from 1950 to 2000. Three of the meta-epidemiological studies (3-5) (1679 RCTs from 184 meta-analyses) contained information about allocation concealment. In 391 (23%) RCTs, allocation concealment was considered adequate while in 950 (57%) it was unclear; in 338 (20%) it was inadequate. Over time, the proportion of RCTs in which reported allocation concealment was adequate remained approximately constant until 1995, after which it increased to 32% (Table1). Following the publication of the CONSORT statement the proportion of RCTs with adequate reported allocation concealment increased to 44%. Conclusions: In this group of RCTs included in meta-epidemiological studies, the proportion with adequate allocation concealment has improved since the mid 1990s. Publication of the CONSORT statement may have reinforced this improvement in trial quality.
(1) Begg C, Cho M, Eastwood S, Horton R, Moher D, Olkin I et al. Improving the Quality of Reporting of Randomized Controlled Trials - The Consort Statement. JAMA 1996; 276(8):637-639. (2) Altman DG, Schulz KF, Moher D, Egger M, Davidoff F, Elbourne D et al. The revised CONSORT statement for reporting randomized trials: Explanation and elaboration. Annals of Internal Medicine 2001; 134:663-694. (3) Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias - Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. Journal of the American Medical Association 1995; 273(5):408-412. (4) Jüni P, Holenstein F, Sterne J, Bartlett C, Egger M. Direction and impact of language bias in meta-analyses of controlled trials: empirical study . International Journal of Epidemiology 2002; in press. (5) Royle P, Milne R. Literature searching for randomised controlled trials used in Cochrane reviews: rapid versus exhaustive searches. International Journal of Technology Assessment in Health Care 2003; 19(4):1-13.