Sensitivity to change and the effect of mode of administration on health status measurement.

A measure of global health status, the McMaster Health Index Questionnaire (MHIQ), was assessed to determine two important measurement properties related to its reliability and validity--sensitivity to change and the effect of mode of administration. Ninety-six patients in a physiotherapy clinic were randomly assigned to three mode-of-administration study groups, administered the MHIQ at four points in time including at admission and discharge from the clinic, and assessed for change by their physiotherapist. MHIQ physical function, social function, and emotional function retest scores obtained by self-completion within a 1-week interval were most stable. Physical function scores by any of self-completion, telephone interview, or personal interview were sensitive to change, that is, they improved dramatically by the time of discharge from the clinic. Mode of administration did not affect the size of the change scores. Changes reflected by the physical function scores correlated with changes in physical function reported by a patient's physiotherapist. No systematic changes occurred with social and emotional function scores; this is not surprising in a group of patients with predominantly physical function problems.