Investigating the patient acceptable symptom state cut-offs: longitudinal data from a community cohort using the shoulder pain and disability index

This prospective study aimed to determine the patient acceptable symptom state (PASS) cut-off for the patient reported outcome measure shoulder pain and disability index (SPADI), and evaluate predictors of PASS achievement following standard shoulder care. Patients with shoulder pain, referred for shoulder ultrasound were recruited from a community cohort. Patients completed both SPADI (scored 0-130) and a question on symptom state and followed-up at 6 months. PASS was calculated from Rasch-transformed scores using 2 methods: the 75th percentile of the cumulative response curve and the receiver operating characteristic curve (ROC). Logistic regression was used to identify factors associated with PASS. 304 participants (169 females, mean age 57.2 years) were included. At 6 months, 193 (63%) reported PASS. The association between SPADI at 6 months and PASS depended on baseline SPADI (interaction p = 0.036). Those with higher baseline scores had higher 6 months PASS cut-offs. Using the 75th percentile method, the 6 months total SPADI cut-off was 49.2 in those starting in the highest tertile at baseline compared to 39.4 in the lowest tertile: 46.4 vs. 36.7 for pain, 46.8 vs. 25.1 for disability. The ROC method yielded similar results. We have shown for the first time that the PASS cut-off for SPADI is dependent on baseline severity scores. Understanding the SPADI PASS threshold is important for clinical research to allow standardised reporting of shoulder intervention success at the patient level.