International Journal of

Radiation Oncology biology

physics

www.redjournal.org

COMMENTS We Need Better Figures! To the Editor: In the health-related scientific literature, the Kaplan-Meier method is commonly used to generate an estimate of survival when follow-up is less than complete (1). In a similar fashion, the cumulative incidence method is frequently invoked to estimate time to an event because it specifically adjusts for other competing risks (2). The results of these analyses are typically displayed in figures within scientific reports. These figures should be designed to provide the reader with sufficient information to make judgments about the content. It is my contention that the figures published in many reports do not meet this standard. Allow me to make my case. Although no rigorous guidelines have been published, one article published more than a decade ago suggested some best practices (3). In my opinion, there are at least four elements that should be provided for every Kaplan-Meier or cumulative incidence estimate in a scientific paper. First, a confidence interval should be included in the text for each estimate. In addition, three other elements should be evident from the figures: (1) the number of patients at risk; (2) censoring marks; and (3) the curves should be truncated when there are fewer than 10 patients at risk. In the November 1, 2013, edition of the International Journal of Radiation Oncology, Biology, Physics (the Red Journal), nine articles included figures with Kaplan-Meier or cumulative incidence methods. I examined each of the nine articles and determined whether the four elements listed above were present. The results are listed in Table 1. The good news is that censoring marks were evident in a majority of figures, but the remaining elements were rarely present, and I could find no evidence that any of the figures were truncated when fewer than 10 patients were at risk. The lack of confidence intervals is a recurring problem (4, 5). I freely admit that this analysis is not rigorous, and it could be that this one edition is not representative of the Red Journal, but I suspect a larger sample would produce the same results.

Table 1

Analysis of figures Element

Confidence interval of estimate No. of patients at risk Censoring marks Curve truncated with

We need better figures!

We need better figures! - PDF Download Free
113KB Sizes 0 Downloads 0 Views