A compression of Kaplan Meier vs. Weighted Kaplan-Meier in Comparing Estimation of Heavy Censoring Data

Khalid Shoaib, Dr. Ahmed Hamdi, Dr. Al Taiyb Ahmed


This study aimed to compare estimations of Kaplan-Meier (K-M) and Weighted Kaplan-Meier (W-K-M) as an alternative method to deal with the problem of heavy-censoring data for Children under-five years, whom do not reach the event of interest during the end period of the study. Usually, this kind of biostatistics study has been estimated based on K-M. In such situations survival probabilities, can be estimated for censored observation by K-M estimator. However, in case of heavy censoring these estimates are biased and overestimate the survival probabilities. For heavy censoring a new method was proposed (Bahrawar Jan, 2005) to estimate the survival probabilities by weighting the censored observations by non-censoring rate. But the main defect in this weighted method is that it gives zero weight to the last censored observation. The survival rates of the patients with standard error estimation based on K-M vs. W-K-M for 5 years shown in Table 3. In cases where censoring assumption is not made, and the study has many censored observations, estimations obtained from the K-M are biased and are estimated higher than its real amount. But W-K-M decreases bias of survival probabilities by providing appropriate weights and presents more accurate understanding. Weighted Kaplan-Meier was the suitable method to estimate the Survival Time of these patients, have determined after surgery at Jafar ibn Oaf Hospital for Children in Sudan form January 2012 to December 2016. The five years’ survival rate for these patients were evaluated based on K-M and W-K-M. A total of 245(22%) Children<5 years passed away by the end of the study and 853(78%) Children<5 years were censored. The median of survival time for these patients was 16 days.

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