Postal and face-to-face administration of stroke outcome measures: can mixed modes be used?

BACKGROUND AND PURPOSE Different modes of administration are used to collect stroke outcomes, even within the same study, potentially leading to different results. We investigated the effect of administration mode (postal questionnaire; face-to-face interview) on self-reports of activities of daily living and mood. METHODS The study was nested within a poststroke motivational interviewing trial. Activities of daily living (Barthel; Nottingham Extended) and mood (General Health Questionnaire; Yale) were collected at 3 and 12 months via postal questionnaire. Participants were approached to respond again via face-to-face interview. Paired t tests (McNemar test) and intraclass correlation coefficients (Cohen κ) were used, with 95% CI, to compare scores (items). RESULTS Forty-four participants consented. Only Barthel scores were significantly different; they were 1.0 (95% CI, 0.5-1.6) higher face-to-face. The intraclass correlation coefficient for the Barthel was 0.90; for the other scales it was between 0.83 and 0.87. The Yale κ was 0.72. CONCLUSIONS Modes of administration might be used interchangeably, albeit in conjunction with corrections for the Barthel.