Reliability of ratings on the Glasgow Outcome Scales from in-person and telephone structured interviews

Objective: To determine test-retest reliability and interrater reliability for structured interviews for the Glasgow Outcome Scale (GOS) using in-person and telephone contact. Methods: Study 1: Thirty head-injured patients were interviewed face-to-face and then reinterviewed by telephone a few days later by the same rater. Study 2: Fifty-six head-injured patients were interviewed by telephone and then face-to-face interviews were carried out by a different person up to 1 month later. Agreement between ratings on the GOS and the extended GOS (GOSE) in each of the studies was assessed using the K statistic weighted with quadratic weights. Results: Values Of kappa(w) for the test-retest reliability study were .92 for both GOS and GOSE, and for interrater reliability study were .85 for the GOS and .84 for the GOSE. Conclusions: The findings indicate good test-retest and interrater reliability for the structured interviews. In most circumstances a structured interview over the telephone can provide a reliable assessment of the GOS, and can safely be substituted for in person contact.