Cross-Cultural Adaptation, Validity, and Reliability Study of the Indonesian Version of the Constant Score in Patients With Shoulder Pain

Abstract

Background: Shoulder pain is one of the main symptoms of patients treated at orthopaedic clinics. The Constant score (CS) is widely used in the literature to assess shoulder functional outcomes. To the authors’ knowledge, no outcome measure has been related to shoulder complaints in Indonesia. Purpose: To perform a translation and cross-cultural adaptation and assess the validity and reliability of the Indonesian CS (CS-INA) as a shoulder functional assessment instrument in Indonesia. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: After a translation cross-cultural adaptation of the CS into the Indonesian language was performed, the validity and reliability of the CS-INA were investigated. Data from patients with shoulder pain were collected consecutively in the orthopaedic clinic of 2 tertiary hospitals in Jakarta in 2023. The validity and reliability study of the final version of the CS-INA was conducted by 1 researcher in 2 meetings within 1 week. The Indonesian version of the 36-item Short Form Survey (SF-36) questionnaire was also given to the respondents. The correlation between CS-INA and SF-36 was determined to evaluate construct validity, whereas internal consistency, intraclass correlation, standard error of measurement (SEM), and minimal detectable change (MDC) were calculated to provide data on reliability. Results: A total of 102 shoulders (101 patients) were included in the study. CS-INA showed excellent construct validity with SF-36 (Pearson correlation 0.90; P < .05). The reliability study showed good internal consistency (Cronbach α = 0.85) and intraclass correlation (ICC = 0.86). The SEM of the test and retest was 7.37, whereas the MDC was 14.3. No floor or ceiling effects were observed in this study. Conclusion: The Indonesian version of the Constant score showed good validity and reliability for the Indonesian population experiencing shoulder pain.