Measuring quality of life in clinical research - Part 2.

This article deals with the various aspects of health-related quality of life (QoL) assessments, building upon a previous discussion of the concept and its measurement types. Specifically, the article will delve into number and timing of QoL assessments, calculating scores from QoL instruments, determining clinically meaningful changes in QoL, sample size calculation when QoL is an endpoint and handling missing data in QoL assessments.