title: Meta-analysis of failure-time data with adjustment for covariates.
abstract: The objective of this study was to present and illustrate a technique for combining failure-time data from various sources, adjusting for differences in case-mix among studies. Based on the proportional-hazards model and the actuarial life-table approach, the method used assumes that the variation across studies is in part due to heterogeneity of the case-mix and adjusts for the case-mix before pooling results. As an example, the technique is applied to life-table data from six selected papers reporting patency of affected arteries following femoropopliteal angioplasty. Published 4- and 5-year patency results ranged from 25% to 58%, with a pooled five-year cumulative patency rate (without adjustment for case-mix) of 45% (+/- 2%). The populations in these studies, however, differed markedly in the prevalence of factors with prognostic value: type of lesion and distal runoff vessels. After adjustment for these differences in case-mix, the pooled five-year patency rates ranged from 60% (+/- 2%) for patients with stenotic lesions and good runoff to 24% (+/- 9%) for those with occlusion and poor runoff. The authors conclude that pooling studies without considering the effect of case-mix yields an average result with inappropriately narrow confidence intervals that does not reflect the variability across subgroups. The presented technique provides a method for combining failure-time data, adjusting for case-mix.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: M G
authors.initials: MG
authors.lastname: Hunink
authors.forename: J B
authors.initials: JB
authors.lastname: Wong
mesh_terms: D000704:Analysis of Variance; D000800:Angioplasty, Balloon / Q000706:statistics & numerical data; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D007511:Ischemia / Q000401:mortality / Q000628:therapy; D007866:Leg / Q000098:blood supply; D015993:Life Tables; D009010:Monte Carlo Method; D016016:Proportional Hazards Models; D012306:Risk; D016019:Survival Analysis; D017211:Treatment Failure; D014654:Vascular Patency / Q000502:physiology