ABSTRACT
Missing self-assessments of HRQoL occur in most longitudinal studies. Because the patients participating in these trials are free-living individuals and often experience disease-and treatment-related morbidity and mortality, missing assessments are inevitable. Missing HRQoL data may occur for reasons totally unrelated to the subjects’ current quality of life (a missed appointment due to a snowstorm) or may be intimately related (severe episodes of nausea or vomiting). The term missing is sometimes used to include only assessments expected according to the guideline of the protocol; another term used for this narrow definition is noncompliance. The term missing often has a broader meaning to include missing for any reason, including unavoidable attrition due to death or termination of follow-up as specified in the protocol.
Terminology
