Comorbidity, disease burden and mortality across age groups in a Swedish primary care asthma population: An epidemiological register study (PACEHR).

Background: Asthma is often associated with other diseases. To identify and manage comorbidities is important, as these conditions may increase the disease burden.

Objective: To describe the prevalence of comorbidities, disease burden and mortality across age groups in a large Swedish primary care real-life asthma population.

Methods: Observational cohort study of asthma patients, all ages, identified from electronic medical records by ICD-10-CM code, data from 36 primary care centers. Data were linked to national mandatory Swedish health registers. Comorbidities were identified by ICD-10-CM codes and collected from electronic medical records and the National Patient Registers, mortality data from the Cause of Death Register. Exacerbations were defined as hospitalizations due to asthma, and/or emergency visits at hospital and/or prescription claims of oral steroids.

Results: In total 33,468 patients (58% women) were included. The most prevalent comorbidities were acute upper respiratory tract infection (53%), rhinitis (25%), acute lower respiratory tract infection (25%), hypertension (21%), anxiety and depression (20%). The comorbidities associated with highest risk for an exacerbation were COPD OR 1.98 (95%CI: 1.80-2.19), nasal polyps OR 1.75 (95%CI: 1.49-2.05) and rhinitis OR 1.52 (95%CI: 1.41-1.63). All-cause mortality was similar to the Swedish population, 1011 deaths per 100,000 person/year compared with 1058 deaths (standardized risk = 0.99 [95%CI:0.95-1.04]). The pulmonary related death rate was greater in the study population versus the Swedish population (122 versus 72 per 100,000person/year).

Conclusion: Comorbid disease was frequent in this large real-life asthma population with an impact on exacerbations. To identify and treat comorbidities with impact on asthma outcomes are essential to improve asthma care.