Minimal important difference after hand surgery: a prospective assessment for DASH, MHQ, and SF-12.

INTRODUCTION: Minimal important difference (MID) score is an important measure for surgical clinical research and impacts on treatment decisions. Our approach considered patient satisfaction as the relevant anchor criteria. The aims of this study were: determine after surgery MID for three relevant questionnaires: Disabilities of the Arm, Shoulder and Hand (DASH), Michigan Hand Questionnaire (MHQ), and Short Form 12 (SF-12); and assess the correlation between these scores and patient reported satisfaction.

METHODS: Adult patients where surgery was indicated for any hand/wrist conditions. Study was conducted in a teaching hospital, São Paulo, Brazil. Participants responded to DASH, SF-12, MHQ, and a Likert satisfaction scale before and three months after a procedure. Satisfaction was considered as the anchor for determining MID after a procedure. The correlation between satisfaction and the instruments were measured. Two statistical approaches were utilized for determining MIDs and were used for consistency and generalizability purposes. For MID determination, receiver operating curves were utilized and MID cut-offs were followed by sensitivity and specificity measures.

RESULTS: Fifty patients were included with no follow-up losses. MID for DASH was 18.8 and 15.4. MID for MHQ was 14.7 for both approaches. Data from SF-12 was not reliable after statistical analyses and demonstrated poor correlation with patient satisfaction. MID for DASH and MHQ were found and demonstrated larger standards than literature-reported patients when surgery was not the main intervention. DASH and MHQ had moderate correlation with patient reported satisfaction. SF-12 MID was not reliable and had poor correlation to patient satisfaction. These data suggests that ambulatory hand surgery patients may have greater expectations regarding improvement than other patients.