Introduction: Asthma is a common chronic disease in adults and exacerbations result in significant morbidity. We assessed the association between demographic and clinical risk factors and asthma-related hospital admissions in adults, and estimated the proportion of hospital admissions potentially attributable to modifiable risk factors.

Methods: Cohort study of English primary care records from 1st January 2017 to 31st December 2019 in the Clinical Practice Research Datalink Aurum database, and linked Hospital Episode Statistics Admitted Patient Care data, using descriptive statistics, negative binomial regression and population attributable risk fractions (PAF).

Results: 13,186 of 1,179,410 (1.1%) adults with asthma experienced at least one asthma-related hospital admission during the study period. Females (HR 1.61, 95% CI 1.54 to 1.68), black (1.46, 1.30 to 1.64), mixed (1.25, 1.07 to 1.45) and Asian (1.60, 1.48 to 1.74) ethnic groups, current smokers , ?6 SABA inhaler prescriptions, and most socioeconomically deprived quintile (1.43, 1.33-1.54) were at increased risk of hospital admission. The highest proportion of asthma-related hospital admissions was attributable to obesity (PAF 23.3%, 95% CI 20.5 to 26.1), followed by depression (11.1%, 9.1 to 13.1), allergies (6.2%, 4.4 to 8.0), smoking (4.3%, 3.0 to 5.7), GORD (2.3%, 1.2 to 3.4), anxiety (2.0%, 0.5 to 3.6) and chronic rhinosinusitis (0.8%, 0.3 to 1.3).

Conclusion: Our study highlights important risk factors for asthma attacks requiring hospitalisation in adults. Identification and treatment of modifiable risk factors has significant potential to reduce associated hospital admissions.