Study of Social Loss or Gain from a Particular Cause: Scope for the Developing Countries - a Review with Reference to Cancer

Incidence rates have long been used to assess the burden of different diseases in a population, whereas lossdue to occurrence of diseases is studied using the death rates. Death rates however, are based on and thereforedescribe, only number of lives lost. There have been two approaches to arrive at the actual loss or gain from aparticular cause viz. Person years of life lost (PYLL) approach and cause elimination life table (CELT) approach.This review covers these approaches and the competing risk theory and models focusing on the methodologicaldevelopments. A summary of the conceptual and methodological developments on these concepts has also beenpresented. There are eight possible approaches in dealing with the loss in the presence or gain in the absence ofa particular cause of death depending upon the preferences related to PYLL/CELT approach, modeling/descriptive approach, considering or without considering competing causes. A close look at the two basicapproaches reveals that PYLL and cause elimination are just different terminologies used to address the samequantity, loss in the presence or gain in the absence. As far as descriptive vs. modeling approaches are concerned,all the descriptive procedures can be put in the form of models and all the models can be presented in a descriptiveway. Regarding results using different models, no practical difference exists in the results based on differentmodels for competing risks. However, exclusion of the competing risks may result in a considerable bias in thedeveloping countries where general mortality is relatively higher. This review study suggests freedom in theselection of a modeling or a descriptive approach without any considerable loss of accuracy but at the same timeemphasizes the consideration of the competing risks. An empirical study may be recommended to confirm theconclusions of this study.