Estimating Mean Quality Adjusted Lifetime with Censored Data

In the clinical trials of chronic diseases such as cancer or AIDS, it has been increasingly recognized that it is not enough just to consider simple time to event end points. For example, a new experimental drug may prolong overall survival time of patients, but in the meantime, it can be toxic for a longer period of time. Therefore, the trade-off between the quality and quantity of life of patients needs to be considered. The concept of quality adjusted survival analysis arises from situations like this. Quality adjusted survival analysis is a method that puts patients’ health status on a utility scale, with coefficients ranging from 0 to 1, where 1 represents a state of perfect health, and 0 a state equivalent to death. Quality adjusted lifetime (QAL) is simply the linear combination of time spent at each health state weighted by