The Shoulder Pain and Disability Index demonstrates factor, construct and longitudinal validity

BMC Musculoskelet Disord. 2006 Feb 10;7:12. doi: 10.1186/1471-2474-7-12.

Abstract

Background: The Shoulder Pain and Disability Index (SPADI) is a self-report measure developed to evaluate patients with shoulder pathology. While some validation has been conducted, broader analyses are indicated. This study determined aspects of cross-sectional and longitudinal validity of the SPADI.

Methods: Community volunteers (n = 129) who self-identified as having shoulder pain were enrolled. Patients were examined by a physical therapist using a standardized assessment process to insure that their pain was musculoskeletal in nature. This included examination of pain reported during active and passive shoulder motion as reported on a visual analogue pain scale. Patients completed the SPADI, the Coping Strategies Questionnaire (CSQ) and the Sickness Impact Profile (SIP) at a baseline assessment and again 3 and 6 months later. Factor analysis with varimax rotation was used to assess subscale structure. Expectations regarding convergent and divergent subscales of CSQ and SIP were determined a priori and analysed using Pearson correlations. Constructed hypotheses that patients with a specific diagnosis or on pain medication would demonstrate higher SPADI scores were tested. Correlations between the observed changes recorded across different instruments were used to assess longitudinal validity.

Results: The internal consistencies of the SPADI subscales were high (alpha > 0.92). Factor analysis with varimax rotation indicated that the majority of items fell into 2 factors that represent pain and disability. Two difficult functional items tended to align with pain items. Higher pain and disability was correlated to passive or negative coping strategies, i.e., praying/hoping, catastrophizing on the CSQ. The correlations between subscales of the SPADI and SIP were low with divergent subscales and low to moderate with convergent subscales. Correlations, r > 0.60, were observed between the SPADI and pain reported on a VAS pain scale during active and passive movement. The two constructed validity hypotheses (on diagnosis and use of pain medications) were both supported (p < 0.01). The SPADI demonstrated significant changes over time, but these were poorly correlated to the SIP or CSQ suggesting that these scales measure different parameters.

Conclusion: The SPADI is a valid measure to assess pain and disability in community-based patients reporting shoulder pain due to musculoskeletal pathology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Psychological*
  • Adult
  • Aged
  • Cross-Sectional Studies
  • Disability Evaluation*
  • Factor Analysis, Statistical
  • Female
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Pain Measurement / methods*
  • Reproducibility of Results
  • Shoulder Pain / diagnosis*
  • Shoulder Pain / psychology*
  • Surveys and Questionnaires