Review of survival analyses published in cancer journals

Abstract

Summary Survival analysis has found widespread applications in medicine in the last 10-15 years. However, there has been no published review of the use and presentation of survival analyses. We have carried out a systematic review of the research papers published between October and December 1991 in five clinical oncology journals. A total of 132 papers were reviewed. We looked at several aspects of study design, data handling, analysis and presentation of the results. We found that almost half of the papers did not give any summary of length of follow-up; that in 62% of papers at least one end point was not clearly defined; and that both logrank and multivariate analyses were frequently reported at most only as P-values [63/84 (75%) Survival analysis has found widespread applications in medicine in the last 10-15 years (Andersen, 1991), particularly in clinical oncology, and its correct application and presentation is critically relevant for much of the cancer literature. Although the use of statistical methods in medicine has been subjected to much scrutiny (see Altman, 1982Altman, , 1991, we believe that there has not been any published review of the use of survival analysis methods in medical journals. Hence, we have carried out a systematic review of the appropriateness of the application and presentation of survival analyses in clinical oncology journals. We have focused on the size of the studies being published, the adequacy of the description of the data analysed (with particular interest given to the length and quality of follow-up and the clarity of the end points of interest) and the choice and quality of univariate, multivariate and graphical analyses. In the light of disappointing findings, we discuss existing guidelines and present some new guidelines aimed in particular at presentation. MethodsWe examined all papers published in British Journal of Cancer, European Journal of Cancer, Journal of Clinical Oncology and American Journal of Clinical Oncology between October and December 1991 which included analyses of survival data. There were 132 papers which reported at least one of the following: Kaplan-Meier or actuarial survival curves; logrank or related tests; parametric or semiparametric survival analyses. Those papers with survival data which did not present any of these analyses, and thus were not included, were largely phase I or II clinical trials.The 132 papers were reviewed using a standard form that had been tested in a small pilot study of 20 papers which were read by all four authors. When the form was finalised each paper was read by two of the authors according to a balanced randomisation scheme. Disagreements between reviewers were resolved in paired discussions and by discussion between all four reviewers on the rare occasions when it was necessary.The assessment form included separate sections relating to distinct aspects of each paper. It also included the time taken by each author to extract the information from the paper onto the form as an indication of the clarity of each...

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