The Kushida Index as a screening tool for obstructive sleep apnoea-hypopnoea syndrome

Objectives To test the validity of the Kushida Index for screening for sleep apnoea in a West of Scotland adult population. Methods Specific intra-oral measurements and respiratory polysomnography were carried out on 71 patients in this prospective study. The intra-oral measurements were applied to the Kushida formula to obtain a value for the Kushida Index. This value was compared to the diagnosis obtained using polysomnography in the conventional manner. Results The sensitivity of the Kushida Index in this present study was 68% (95% CI 50-81) and the specificity was 71% (95% CI 52-84). The positive predictive value was 71% and the negative predictive value was 67%. The Mallampati score, Epworth sleepiness score and enlargement of the tongue, soft palate or tonsils were not statistically significantly related to a diagnosis of sleep apnoea (p > 0.05). Conclusion With the limited sensitivity and specificity of the Kushida Index demonstrated in this study, this test cannot be recommended as a screening tool for sleep apnoea in a West of Scotland population.