Reliability and validity testing of the Patient and Observer Scar Assessment Scale in evaluating linear scars after breast cancer surgery.

BACKGROUND: The Patient and Observer Scar Assessment Scale is a promising new method incorporating observer and patient ratings in evaluating burn scars. The authors compared this tool to the Vancouver Scar Scale in a cohort of women with linear scars from breast cancer surgery.
METHODS: Twenty women with newly diagnosed breast cancer were prospectively accrued. Thirty-one scars were evaluated. The median time from surgery to scar assessment was 8 weeks (range, 3 to 25 weeks). Observer assessment was performed by three independent raters using the Vancouver scale and the observer component of the new tool. Patient self-assessment was performed using the patient component of the tool. Internal consistency, interobserver reliability, and convergent validity were examined.
RESULTS: Internal consistency was acceptable for the Vancouver scale and both components of the new tool (Cronbach's alpha, 0.71, 0.74, and 0.77, respectively). Interobserver reliability was substantial with both the Vancouver scale and the observer tool (average measure intraclass coefficient correlation, 0.78 and 0.60, respectively). The observer tool and Vancouver scale correlated significantly with each other (p < 0.001), but only the observer tool correlated well with patients' ratings (p = 0.04).
CONCLUSIONS: In surgical scar assessment, the new Patient and Observer Scar Assessment Scale and Vancouver Scar Scale were both associated with acceptable internal consistency and interobserver reliability. The new tool is more comprehensive and has higher correlation with patients' ratings. These findings support the use of the new tool as a reliable, valid, and comprehensive approach to assess linear surgical scars.