Asthma associated with chronic rhinosinusitis: a population-based study

Background: Few studies have investigated the relationship between asthma and chronic rhinosinusitis (CRS). The present study investigated the association between asthma and the risk of CRS in a large national sample. Methods: Patients newly diagnosed with asthma (International Classification of Diseases, Ninth Revision [ICD-9], Clinical Modification code 493) between 2000 and 2008 were identified from the Taiwan National Health Insurance Research Database. The cases were compared with sex-, age-, residence-, and insurance premium–matched controls, and both groups were followed until the end of 2009 for incidences of CRS with or without nasal polyps (CRSwNP or CRSsNP, respectively). Competing risk-adjusted Cox regression analyses were performed after adjustment for sex, age, residence, insurance premium, steroid use, hyperlipidemia, diabetes, hypertension, coronary artery disease, Charlson comorbidity index score, and mortality. We also performed a case-control study to determine the association between asthma and CRS. Results: The cohort study analysis examined 81,462 patients with a mean ± standard deviation (SD) follow-up period of 5.8 ± 2.4 years. Asthma was an independent predictor of CRSsNP (hazard ratio = 2.58; 95% confidence interval [CI], 2.20 to 3.03; p < 0.001) in the fully adjusted models. In the case-control analysis, both CRSwNP and CRSsNP were associated with asthma in the fully adjusted models. Conclusion: Asthma was associated with increased risks of CRSwNP and CRSsNP, independent of several potential confounding factors.