Interpretation of Tonsillectomy Outcome Inventory-14 scores: a prospective matched cohort study

Purpose Knowledge of disease-specific instruments enables the evaluation of health- related quality-of-life (QoL) change associated with chronic and recurrent tonsillitis in adults. The main objective was to explore the interpretation of scores according to the throat-related QoL instrument, Tonsillectomy Outcome Inventory-14 (TOI-14), by determining the typical scores in healthy subjects and patients and define the minimum important change (MIC). Methods We performed a prospective matched cohort study in a secondary care area of Oulu University Hospital. The surgical cohort consisted of 42 patients referred to tonsillectomy due to recurrent or chronic tonsillitis. The control cohort consisted of 42 age- and sex-matched healthy controls obtained from the escorts of patients in the same hospital. We translated and validated the Finnish TOI-14 instrument and collected TOI-14 scores at entry and at 6 months and compared results to the anchor question. Results At entry, the mean TOI-14 scores were significantly higher in the surgical cohort than in the control cohort [mean (95% confidence interval)] 33.0 (27.0–39.1) vs. 5.0 (3.6–6.4), respectively. At 6 months follow-up, the mean TOI-14 scores had improved markedly after tonsillectomy to the level of the control cohort. In the healthy population, the score was in most cases under 15.0 points. In patients, a score of about 20.0 indicated mild symptoms, 30.0 moderate symptoms and 40.0 or higher intense symptoms. The MIC value was 10.0 points. Conclusions These results enable the more accurate interpretation of the scores of the only disease-specific QoL instrument for adult throat-related diseases.