Construct validity and responsiveness of the Duke Activity Status Index (DASI) as a measure of recovery after colorectal surgery.

Abstract

Returning to preoperative levels of physical function is highly valued by patients recovering from surgery. The Duke Activity Status Index (DASI, a 12-item questionnaire) may be a simple yet robust tool to assess postoperative recovery of functional capacity. This study assessed construct validity and responsiveness of the DASI as a measure of recovery after colorectal surgery. Data from a trial on early mobilization after colorectal surgery were analyzed. Patients completed the DASI questionnaire preoperatively and at postoperative weeks (POW) 2 and 4. Construct validity was assessed by testing the primary a priori hypotheses that postoperative DASI scores (1) are higher in patients without vs with postoperative complications and (2) correlate with six-minute walk test distance (6MWD). Exploratory analyses assessed the association between DASI scores and (1) preoperative physical status [higher (ASA ≤ 2) vs lower (ASA > 2)], (2) stoma creation (no stoma vs stoma), (3) age [younger (≤ 75years) vs older (> 75years)], (4) time to readiness for discharge [shorter (≤ 4days) vs longer (> 4days)], and (5) surgical approach (laparoscopic vs open). Responsiveness was assessed by testing a priori hypotheses that DASI scores are higher (1) preoperatively vs at POW2 and (2) at POW4 vs POW2. Mean differences in DASI scores were obtained using linear regression. The association between DASI and 6MWD was assessed via Pearson correlation. We analyzed data from 100 patients undergoing colorectal surgery (mean age 65; 57% male; 81% laparoscopic). Mean DASI scores were 47.9 ± 12.1 preoperatively, 22.4 ± 12.7 at POW2, and 33.2 ± 15.7 at POW4. The data supported our two primary construct validity hypotheses, as well as 3/5 exploratory hypotheses. Both responsiveness hypotheses were supported. Our findings support that the DASI questionnaire can be a useful tool to assess postoperative recovery of functional capacity in research and clinical practice.