A comparison between measurement properties of four shoulder-related outcome measures in Nepalese patients with shoulder pain

Abstract

Purpose: The Patient-Specific Functional Scale (PSFS), Disability of the Arm, Shoulder and Hand (DASH), Quick-DASH, and Shoulder Pain and Disability Index (SPADI) are frequently used instruments in shoulder functional assessment. They are available in Nepali and all but the PSFS has been validated for shoulder assessment. Therefore, the aim of this study was to validate the Nepali PSFS in shoulder pain patients and to compare validity, reliability, and responsiveness of all four instruments to provide a recommendation for their use. Method: Patients attending physiotherapy completed the Nepali PSFS at baseline and follow-up (1–3 weeks). It was tested for reliability using internal consistency (Cronbach’s α), intraclass correlation coefficient (ICC), construct validity by hypothesis testing and responsiveness by anchor-based method using Area Under the Curve (AUC). The instruments were compared based on reported measurement properties and patients’ preference. Results: 156 patients enrolled at baseline and 121 at follow-up. The PSFS showed sufficient reliability (α = 0.70, ICC = 0.82), construct validity (all three hypotheses met) and responsiveness (AUC = 0.83). Measurement property comparison demonstrated adequate reliability and validity, while PSFS was the most responsive instrument. Patients favoured the verbal rating scale of the DASH/Quick-DASH. The DASH had a lower completion rate for ‘culturally sensitive’ and ‘uncommon’ activities. Conclusion: The Nepali PSFS is a reliable, valid, and responsive instrument in shoulder functional assessment. The combined use of the Quick-DASH or SPADI with the PSFS is recommended for a comprehensive assessment of Nepali shoulder pain patients in clinical and research settings. They are shorter, more appropriate to the Nepali context and provide balanced self-evaluation.