Functional Comorbidity Index in Sleep Apnea

Objectives (1) Measure the association between the Functional Comorbidity Index (range, 0‐18) and physical function health status (SF‐36 Physical Function domain), general physical health status (SF‐36 Physical Component Score), and general mental health status (SF‐36 Mental Component Score) outcome measures in a cohort of sleep apnea patients. (2) Test if the Functional Comorbidity Index is more strongly associated (a better predictor) than the well‐known Charlson Comorbidity Index (range, 0‐37) with these SF‐36 outcome measures. Study Design Cross‐sectional study. Setting University of Washington Sleep Center. Subjects and Methods In a cohort of newly diagnosed obstructive sleep apnea patients (N = 233), we obtained scores for the Functional Comorbidity Index, Charlson Comorbidity Index, and SF‐36. We calculated Spearman correlations and adjusted coefficients of determination ( R 2 ) with multiple linear regression, adjusted for demographic and health covariates. Bootstrapping generated R 2 distributions for statistical comparison. Results Functional Comorbidity Index scores (mean ± standard deviation 2.4 ± 1.7) were more widely distributed than Charlson Comorbidity Index scores (0.7 ± 1.4). The Functional Comorbidity Index was significantly correlated with SF‐36 Physical Function (–0.53, P <. 001), Physical Component Score (–0.44, P <. 001), and Mental Component Score (–0.38, P <. 001). The Functional Comorbidity Index was a better predictor than the Charlson Comorbidity Index of SF‐36 Physical Function ( R 2 mean ± standard error 0.27 ± 0.05 vs 0.17 ± 0.05, P <. 001), Physical Component Score (0.23 ± 0.05 vs 0.17 ± 0.05, P <. 001), and Mental Component Score (0.23 ± 0.05 vs 0.13 ± 0.05, P <. 001). Conclusion The Functional Comorbidity Index is a more robust predictor of general health status than the Charlson Comorbidity Index in obstructive sleep apnea patients.