Measuring quality of life after surgery.

Measures of quality of life are used increasingly to evaluate the outcome of surgical care. Impairment in quality of life is a major reason why patients seek surgical care, and changes in health-related quality of life are how patients assess the effect of treatment. Disease-specific measures focus on a particular health condition and are useful for detecting change resulting from treatment. Generic measures cover a wider spectrum of quality of life, provide a global assessment of a patient's overall health, and allow comparisons with other health conditions. Quality of life is not measured directly but is commonly sampled by using measurement scales in the form of questionnaires. The important properties of quality-of-life measurement scales are reliability, the extent to which a measure provides similar values for individuals with similar underlying quality of life; validity, the extent to which it measures what it purports to measure; responsiveness, the extent to which changes in correlate with true changes in quality of life; and sensitivity, the extent to which a measure can detect meaningful changes in quality of life.