Introduction: While mortality and morbidity are typically measured on binary scales (e.g., alive-dead; better-worse) in medical research and thus odds or relative risk ratios are pooled in systematic reviews/meta-analyses, there are many outcomes that are measured on continuous, interval scales. When the identical scale of measurement is used acoss studies (e.g., length of stay, bilirubin, G11bAI, DBP), then a pooled weighted mean difference can be calculated. When different scales are used to assess a conceptually similar outcome from different studies (e.g.. quality of life, pain, pulmonary function as peak flow, FEV, or %FEV), then a standardized mean difference is used to convert the outcomes to one comparable common metric for pooling and comparison purposes.

Objective: To describe the frequency and appropriateness of use of continuous outcomes in systematic reviews, and the types of problems to which they are applied.

Methods: Descriptive methods (simple counts and percentages) were used to examine systematic reviewss in CDSR.

Results: The complete set of 98 reviews in issue 3 of CDSR (Cochrane Library, BMJ Publishing, April 1996) were examined. These reviews contained a total of 1671 analyses or comparisons, or about 17 outcomes per review. Of the total set of 1671, 164 (about 10%) were outcomes measured on continuous scales, while the remainder were binary outcomes.

Discussion: A content analysis of the systematic reviews in which these 164 continuous outcomes appear is underway. The number and percentage of analyses in which a pooled weighted mean difference was appropriately used will be determined, as well as the frequency with which a pooled standardized mean difference was used or ought to have been used. Anomalies and possible errors will be tabulated (eg, extremely skewed data, questionable measures of variability). Some indication of the scope, use and quality of analyses of continuous outcomes should be possible to serve as a guide for future work.