Comprehensive geriatric assessment is a technique for multidimensional diagnosis of frail elderly people with the purpose of planning and/or delivering medical, psychosocial, and rehabilitative care. When comprehensive geriatric assessment is coupled with some therapy, then the term geriatric evaluation and management (GEM) will be used. Following a brief history of comprehensive geriatric assessment, we describe the varied patterns of GEM program organization and review the literature of studies examining GEM effectiveness. Program diversity complicates drawing firm conclusions about GEM effects; however, the vast majority of studies report positive, if not uniformly significant, results. Our analysis suggests that much of the variability in findings is due to sample size limitations. In order to reach conclusions of program effects across studies and to avoid problems of small sample sizes, we undertook a formal meta-analysis. In this initial meta-analysis, we sought to evaluate the effect of GEM programs on a single outcome: mortality. We pooled all published GEM controlled trials into four major groups: inpatient consultation services, inpatient GEM units, home assessment services, and outpatient GEM programs. Meta-analysis of 6-month mortality demonstrates a 39% reduction of mortality for inpatient consultation services (odds ratio 0.61, 95% confidence interval 0.46-0.81, P = 0.0008) and a 37% reduction of mortality for inpatient GEM units (odds ratio 0.63, 95% CI 0.42-0.93, P = 0.02). Home assessment services reduced mortality by 29% (odds ratio 0.71, 95% CI 0.55-0.90, P = 0.005). On the other hand, no significant survival effect was found for outpatient GEM programs (odds ratio 0.96, 95% confidence interval 0.61-1.49).(ABSTRACT TRUNCATED AT 250 WORDS)