Clinical trial investigators often record a great deal of baseline data on each patient at randomization. When reporting the trial's findings such baseline data can be used for (i) subgroup analyses which explore whether there is evidence that the treatment difference depends on certain patient characteristics, (ii) covariate-adjusted analyses which aim to refine the analysis of the overall treatment difference by taking account of the fact that some baseline characteristics are related to outcome and may be unbalanced between treatment groups, and (iii) baseline comparisons which compare the baseline characteristics of patients in each treatment group for any possible (unlucky) differences. This paper examines how these issues are currently tackled in the medical journals, based on a recent survey of 50 trial reports in four major journals. The statistical ramifications are explored, major problems are highlighted and recommendations for future practice are proposed. Key issues include: the overuse and overinterpretation of subgroup analyses; the underuse of appropriate statistical tests for interaction; inconsistencies in the use of covariate-adjustment; the lack of clear guidelines on covariate selection; the overuse of baseline comparisons in some studies; the misuses of significance tests for baseline comparability, and the need for trials to have a predefined statistical analysis plan for all these uses of baseline data.

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A randomized, single-blind controlled trial was conducted to test the efficacy of a community-based group intervention to reduce fear of falling and associated restrictions in activity levels among older adults. A sample of 434 persons age 60+ years, who reported fear of falling and associated activity restriction, was recruited from 40 senior housing sites in the Boston metropolitan area. Data were collected at baseline, and at 6-week, 6-month, and 12-month follow-ups. Compared with contact control subjects, intervention subjects reported increased levels of intended activity (p < .05) and greater mobility control (p < .05) immediately after the intervention. Effects at 12 months included improved social function (p < .05) and mobility range (p < .05). The intervention had immediate but modest beneficial effects that diminished over time in the setting with no booster intervention.

With a sample survey (N = 266) of elderly adults residing in six housing developments in Massachusetts, we used logistic regression to: (a) identify covariates of fear of falling among all subjects and (b) identify covariates of activity curtailment among the subset of subjects who were afraid of falling. Fifty-five percent of respondents were afraid of falling; of those who were afraid, 56% had curtailed activity due to this fear. Factors associated with fear of falling were: being female, having had previous falls, and having fewer social contacts. Factors associated with activity curtailment among those who were afraid were: not communicating about falls; having less social support; and knowing someone who had fallen. Falls history appears an important contributor to fear of falling, whereas the impact of this fear on activities appears more a function of social support. These findings suggest different strategies for the primary and secondary prevention of fear of falling.

Objectives To review current practice in the analysis and reporting of epidemiological research and to identify limitations.