Risk factors for death from asthma, chronic obstructive pulmonary disease, and cardiovascular disease after a hospital admission for asthma

Abstract

Background: Patients with asthma have an increased risk of death from causes other than asthma. A study was undertaken to identify whether severity of asthma, its treatment, or associated co-morbidity were associated with increased risk of death from other causes.

Methods: Eighty five deaths from all causes occurring within three years of discharge from hospital in a cohort of 2242 subjects aged 16-64 years admitted for asthma were compared with a random sample of 61 controls aged <45 years and 61 aged >/=45 years from the same cohort.

Results: Deaths from asthma were associated with a history of clinically severe asthma (OR 6.29 (95% CI 1.84 to 21.52)), chest pain (OR 3.78 (95% CI 1.06 to 13.5)), biochemical or haematological abnormalities at admission (OR 4.12 (95% CI 1.36 to 12.49)), prescription of ipratropium bromide (OR 4.04 (95% CI 1.47 to 11.13)), and failure to prescribe inhaled steroids on discharge (OR 3.45 (95% CI 1.35 to 9.10)). Deaths from chronic obstructive pulmonary disease (COPD) were associated with lower peak expiratory flow rates (OR 2.56 (95% CI 1.52 to 4.35) for each 50 l/min change), a history of smoking (OR 5.03 (95% CI 1.17 to 21.58)), prescription of ipratropium bromide (OR 7.75 (95% CI 2.21 to 27.14)), and failure to prescribe inhaled steroids on discharge (OR 3.33 (95% CI 0.95 to 11.10)). Cardiovascular deaths were more common among those prescribed ipratropium bromide on discharge (OR 3.55 (95% CI 1.05 to 11.94)) and less likely in those admitted after an upper respiratory tract infection (OR 0.21 (95% CI 0.05 to 0.95)). Treatment with ipratropium bromide at discharge was associated with an increased risk of death from asthma even after adjusting for peak flow, COPD and cardiovascular co-morbidity, ever having smoked, and age at onset of asthma.

Conclusions: Prescription of inhaled steroids on discharge is important even for those patients with co-existent COPD and asthma. Treatment with ipratropium at discharge is associated with increased risk of death from asthma even after adjustment for a range of markers of COPD. These results need to be tested in larger studies.