Chronic disease co-morbidity of asthma and unscheduled asthma care among adults: results of the national telephone health interview survey German Health Update (GEDA) 2009 and 2010

BACKGROUND: Co-morbidities may complicate the clinical management of chronic conditions such as asthma. AIMS: To quantify the strength of the relationship between asthma and other chronic diseases and to analyse whether co-morbidities contribute to unscheduled asthma care. METHODS: Data from two consecutive national telephone health interview surveys (GEDA 2009 and 2010) including a total of 43,312 adults (≥18 years of age) were analysed. Persons with and without a current diagnosis of asthma were compared with respect to concurrent diagnoses (diabetes mellitus, hypertension, chronic heart failure, depression, osteoarthritis, stroke, coronary heart disease, and cancer). Logistic regression models were applied to assess the strength of the association between asthma and co-morbidities in the total study population and, among persons with asthma, between the number of co-morbidities and unscheduled inpatient (hospital admissions and/or emergency department admissions) or outpatient asthma care in the past 12 months. RESULTS: Overall, 5.3% (95% CI 5.0% to 5.6%) of adults reported current physician-diagnosed asthma. Asthma was significantly associated with most of the conditions considered and 18% of persons with asthma had three or more co-morbidities. Adjusted odds ratios (AOR) of unscheduled asthma care increased with numbers of conditions, with AOR 3.40 (95% CI 1.39 to 8.31) for unscheduled inpatient care and AOR 2.32 (95% CI 1.30 to 4.14) for unscheduled outpatient care comparing those with three or more co-morbidities versus those with none. CONCLUSIONS: The magnitude of chronic disease co-morbidity is substantial in asthma, is related to unscheduled asthma care, and implies a significant number of adults with asthma facing complex healthcare needs.