Development and Validation of Stroke-specific Shoulder Disability Index: A Cross-sectional Study

Introduction: Shoulder difficulties are the most prevalent secondary musculoskeletal dysfunction after stroke, accounting for 34-85% of patients. To resolve these issues, a comprehensive evaluation is necessary. Currently, there is no evaluation instrument, that includes all shoulder problems.

Aim: To develop and evaluate the content validity of stroke-specific shoulder disability index, unique to stroke patients.

Materials and Methods: The present study was a cross-sectional content validation study, conducted at a tertiary care hospital from August 2020 to March 2021. Domains included in the scale were muscle tone, pain, subluxation, synergy pattern, active (within synergy, mixed synergy, away from synergy), and passive range of motion, sensation, and Activity of Daily Livings (ADLs) by an exhaustive literature search and direct patient interview. Prior to the construction of the scale, two physiotherapists with relevant field experience were interviewed, to identify domains and items. Then, 10 stroke patients were interviewed to generate new items depending on the challenges they experienced. The scale was subsequently sent to a panel of eight experts for content evaluation.

Results: Initial production yielded 49 items over 10 domains. On the advice of the reviewers, one item was added to the pain domain after the original Delphi survey round. The first-round I-Content Validity Index (CVI)/Average (Ave) score was 0.97, which was a good content validity score; nevertheless, the second round of the Delphi survey was conducted since reviewers suggested modifying the scoring criteria for some domains. Following any required revisions, the scale was resubmitted to a panel of eight experts for final approval. In the second round, the proposed stroke-specific shoulder disability index achieved an I-CVI/Ave score of 0.98, therefore, no extra survey was required.

Conclusion: Stroke-specific shoulder disability index was developed and earned a strong validation score. Therefore, the items collected under various domains, may be utilised to develop a shoulder impairment index, unique to stroke patients.