title: An assessment of methods to combine published survival curves.
abstract: OBJECTIVE
  To assess the accuracies of different techniques for combining published survival curves, for use in disease modeling applications.
  
  
  METHODS
  Five methods were identified: 1) iterative generalized least-squares (IGLS), 2) meta-analysis of failure-time data with adjustment for covariates (MFD), 3) nonlinear regression (NLR), 4) log relative risk (LRR), and 5) weighted LRR (w-LRR). Each method was used to combine the survival curves from eight single-arm Phase II trials of chemotherapy in 918 patients with advanced non-small-cell lung cancer (NSCLC). The resulting summary curves were compared with the curve calculated from the corresponding individual patient data (IPD).
  
  
  RESULTS
  All methods were able to produce accurate summary survival curves statistically similar to the IPD-derived curve. Maximum discrepancies ranged from 1.8% to 4.7%. MFD appeared to be the most accurate when censoring information was complete. Characteristics of the component trials that adversely affected the accuracies of the different techniques were 1) a high proportion of censored observations (MFD); 2) variability in the length of follow-up (IGLS, NLR, LRR, w-LRR); and 3) the heterogeneity of the treatment results (NLR, w-LRR).
  
  
  CONCLUSIONS
  All methods were able to accurately reproduce summary survival curves from the published literature. The best method depends on characteristics of the data and the purpose of the analysis.
authors.affiliation: University of Ottawa and Ottawa Regional Cancer Centre, Ontario, Canada. craig_earle@dfci.harvard.edu
authors.forename: C C
authors.initials: CC
authors.lastname: Earle
authors.forename: B
authors.initials: B
authors.lastname: Pham
authors.forename: G A
authors.initials: GA
authors.lastname: Wells
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000401:mortality*; D017322:Clinical Trials, Phase II as Topic / Q000706:statistics & numerical data*; D006801:Humans; D016018:Least-Squares Analysis; D015993:Life Tables; D008175:Lung Neoplasms / Q000188:drug therapy / Q000401:mortality*; D015201:Meta-Analysis as Topic; D016016:Proportional Hazards Models; D016019:Survival Analysis