Development and testing of a utility measure for major, unipolar depression (McSad)

Objective: To develop and test a direct utility measure (McSad) for major, unipolar depression. Methods: A depression specific, multi-attribute health state classification system was created; clinical validity was evaluated b y experts using specially designed structured exercises; a cross-sectional survey was conducted to obtain directly measured utilities for depression h ealth states. Setting: Tertiary care, university medical centre. Participan ts: Three psychiatrists, 3 psychiatric nurses and 3 social workers assessed depression health state clinical validity. Survey participants were referr ed by psychiatrists and consisted of 105 out-patients, currently in remissi on with at least one episode of major, unipolar depression in the past two years. Survey results: Respondent self-health state utility (mean and 95% c onfidence interval (CI)) was 0.79 (0.74-0.83). Utilities for hypothetical, untreated depression health states were: mild depression, 0.59 (0.55-0.62); moderate depression, 0.32 (0.29-0.34); severe depression, 0.04 (0.01-0.07) . Fifty-six percent of respondents rated severe depression worse than being dead. Utilities for the hypothetical health states were not correlated wit h self-health utility. The intra-class correlation coefficient (ICC) was sa tisfactory for 13 of the 14 health states assessed. Conclusions: McSad was feasible and acceptable in patients with a history of major unipolar depres sion. The utilities for mild, moderate and severe untreated depression show the low health-related quality of life associated with depression. Initial assessments of test-retest reliability and validity yielded satisfactory r esults but further studies are needed to extend our knowledge of the measur ement properties of McSad.