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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00405-020-05832-z) contains supplementary material, which is available to authorized users.