The Dutch Shoulder Pain and Disability Index (SPADI): a reliability and validation study

Purpose To evaluate the reliability and validity of the Dutch Shoulder Pain and Disability Index (SPADI-D). Background The SPADI is recommended and frequently used. However, the validity and reliability of the SPADI-D are unknown. Methods The study population consisted of patients consulting a physical therapist for shoulder pain. We assessed construct validity, using known groups, convergent validity (SDQ) and divergent validity (EQ5D) for which the mean difference or Spearman correlations coefficients were calculated. The factor structure was assessed using principal component factor analysis, and we calculated Cronbach's alpha and the ICC to assess the reliability. Results A total of 356 patients and a randomly selected group of 74 subjects for the reliability analysis were included. There was a significant difference between extreme groups (a high/low level of pain and work absence/presence) in SPADI score. The correlation between the SPADI and the SDQ was 0.69, with the EQ5D mobility-item 0.25 and with the depression-item 0.14. The SPADI consisted of one factor according to principal component factor analysis, which showed high internal consistency (Cronbach's alpha = 0.94 for the total score), and the test-retest reliability was good (ICC = 0.89). Conclusion The Dutch SPADI is a valid and reliable questionnaire for patients in primary care in assessing functional disability.