Construct Validity of a 90-day Physical Recovery Survey Assessment in Adult Acute Respiratory Distress Syndrome (ARDS) Survivors

Abstract Rationale/Introduction: Recovery of physical function to a pre-hospitalization baseline within 90 days is an important outcome in adult ARDS research. While several disability surveys are robust to recall bias and validated for telephone use, none capture a spectrum of physical function from basic activities of daily living to strenuous recreational activities that are relevant to adult ARDS survivors across the lifespan. Methods: In an NIH/NHLBI-funded four-site prospective cohort study of adult ARDS survivors, at a baseline assessment immediately prior to hospital discharge, we asked participants to estimate their pre-hospitalization physical function via basic and independent activities of living (ADLs) surveys, the Precipitating Events Project disability survey, and the Duke Activity Status Index survey, and prospectively assessed grip-strength, Short Physical Performance Battery (SPPB), and six-minute walk distance (6MWD). At 3 months, we repeated these same assessments and asked patients about their perceived recovery via a 5-point Likert scale. We defined “recovered” as reporting no new disability at 3 months compared to the pre-hospitalization baseline based on 14 physical function questions selected from the surveys ranging from basic ADLs to participation in strenuous sports. Results: The study is ongoing. Among 44 ARDS survivors who completed a 3-month follow-up thus far, 29 (66%) were classified as recovered and 15 (34%) as not recovered. Compared to those not recovered, those who recovered had significantly greater grip strength, gait speed, SPPB score, and percent-predicted 6MWD at both hospital discharge and 3-month follow-up (Table 1). Compared to those not recovered, those who recovered had significantly greater median [IQR] gains in SPPB scores (2 [0-5] vs. 7 [7-8]), in gait speed (0.13 m/s [0-0.22] vs. 0.47 m/s [0.22-0.65]), and in percent-predicted 6MWD (0% [0-30] vs. 37% [16-50]), with 6MWD in meters at 3-months being approximately twofold greater in those who recovered. Comparing those recovered vs. not recovered, 74% vs. 13% reported being “nearly” or “completely” recovered. Conclusions: A novel 14-question telephone battery for assessing physical function recovery in ARDS survivors that is based on existing validated survey items demonstrates construct validity with performance-based tests and self-reported recovery at 3-month follow-up. Those who recover have better physical function at hospital discharge and make more substantial gains in physical function over 3 months.