title: Survival analysis, more than meets the eye.
abstract: The log-rank test is a cornerstone of phase III oncology clinical trials. However, there are at least three different mathematical procedures that can be named the log-rank test and two of them are widely used by commercial statistical programs. Consequently, different P values can be obtained. In the case of a borderline statistical significance, this can mean the difference between the evidence (significant P value) and merely an observation. Since all three methods can be reported under the same name, space for possible data manipulation occurs. This should be of a particular concern in a drug regulatory context. Randomized clinical trials with borderline significant results should perhaps be required to report P values calculated by all three methods, in order to properly evaluate drug efficacy. An interactive MS Excel spreadsheet that uses all three logrank test variants is prepared as a supplementary file accompanying this article. Association of high grade of bone marrow fibrosis with poor outcome in patients with myelofibrosis is used as an example.
authors.affiliation: Hematology Department, University Hospital Dubrava, Zagreb, Croatia.
authors.forename: Marko
authors.initials: M
authors.lastname: Lucijanic
authors.affiliation: Pharmacy Department, General Hospital Šibenik, Šibenik, Croatia.
authors.forename: Marko
authors.initials: M
authors.lastname: Skelin
authors.affiliation: Endocrinology, diabetes and metabolism disorders Department, University Hospital Dubrava, Zagreb, Croatia.
authors.forename: Tomo
authors.initials: T
authors.lastname: Lucijanic
mesh_terms: D017326:Clinical Trials, Phase III as Topic / Q000706:statistics & numerical data*; D006801:Humans; D015233:Models, Statistical; D055728:Primary Myelofibrosis / Q000401:mortality*; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D016019:Survival Analysis
keywords: clinical trial; primary myelofibrosis; software; statistics; survival analysis