Reliability and validity of the Greek shoulder pain and disability index in patients with shoulder pain

Background: The Shoulder Pain and Disability Index is one of the most common questionnaire to evaluate the impact of shoulder disorders on function. There is no valid and reliable Greek version of the Shoulder Pain and Disability Index available at present for all shoulder disorders. Therefore, the aim of the current study was to test the reliability and validity of the Shoulder Pain and Disability Index in patients with shoulder pain for at least four weeks. Methods: The validation study was conducted in clinical settings by questionnaires comprising the Greek Shoulder Pain and Disability Index and Disability of the Arm, Shoulder, and Hand questionnaire. 130 (68 women and 62 men) Greek reading patients over 18 years old with shoulder pain for at least four weeks were recruited from physical therapy clinics. Internal consistency of the translated instrument was measured using Cronbach's alpha. to establish test-retest reliability, the patients without any change in their condition after 2-3 days from their initial visit were asked to complete the Shoulder Pain and Disability Index for a second time. An intraclass correlation coefficient was used to assess the test-retest reliability of the Shoulder Pain and Disability Index. The Greek version of the Shoulder Pain and Disability Index and Disability of the Arm, Shoulder, and Hand questionnaire was also administered in both visits. Concurrent validity was measured by correlating the Shoulder Pain and Disability Index with the Greek Shoulder Pain and Disability Index and Disability of the Arm, Shoulder and Hand scale using Pearson's correlation coefficient. Results: The results showed that the Greek Shoulder Pain and Disability Index has good internal consistency (Cronbach alpha = 0.947), test-retest reliability (ICC =0.926) and concurrent validity (r > 0.7). The standard error of measurement (SEM) and the smallest detectable change (SDC) of the Greek SPADI total score were 4.77 and 13.18. Conclusions: The Greek version of the Shoulder Pain and Disability Index is a reliable and valid measure when administered to patients aged over 18 years old with shoulder pain for at least four weeks.