Background: No validated shoulder-specific quality of life measurements exist for patients with scapula alata (SA). The objective was to investigate the content validity of the Western Ontario Rotator Cuff (WORC) Index for SA patients.
Methods: Content validity was evaluated by an expert panel of medical doctors and physiotherapists (n = 6) and a sample of SA patients (n = 44). The Content Validity Index (CVI) and a modified kappa index (κ*) assessed the relevance of WORC Index.
Results: The experts evaluated ten of 21 items as excellent for content validity (I-CVI > 0.78, κ* > 0.74), five items as fair (I-CVI < 0.78, 0.40 < κ* < 0.60), and six were considered content invalid (I-CVI < 0.78, κ* < 0.40). The average scale (S-CVI/Ave) for the entire WORC Index was 0.72.The SA patients evaluated four of 21 items as excellent for content validity (I-CVI > 0.78, κ* > 0.74), nine items as good (I-CVI < 0.78, 0.60 > κ* < 0.74), six as fair (I-CVI < 0.78, 0.40 < κ* < 0.59) and two were considered content invalid (I-CVI < 0.78, κ* < 0.40). The S-CVI/Ave was 0.56.
Conclusion: This study is the first step evaluating content validity in the WORC Index for SA patients. The results indicated that half of the 21 items had excellent or good content validity. Several items need to be discussed by an SA team aiming to find consensus for changing or removing, leaving the possibility to develop a new quality of life measure, the first for SA patients.
Keywords: Content validity; Content validity index; Modified kappa index; Scapula alata; Shoulder-specific QoL measure; Western Ontario Rotator Cuff Index.