Overreliance on Bronchodilators as a Risk Factor for Life-Threatening Asthma

OBJECTIVE: To assess the potential impact on the risk of life-threatening asthma of current recommendations in pharmacotherapy, which emphasize the early use of steroids and the avoidance of beta-agonist overuse.

DESIGN: Nested case-control study.

SETTING: Province of Saskatchewan.

POPULATION STUDIED: From a cohort of 12,301 subjects dispensed 10 or more asthma medications from 1980 to 1987, 129 case patients were identified who had experienced an episode of fatal or near fatal asthma and 129 control patients matched to the cases on age, time period at risk and severity of asthma (as judged by the need for hospitalization for asthma in the preceding two years).

METHODS: Two clinicians reviewed the therapy these 258 subjects had been dispensed over the prior two-year period and classified their treatment as ‘incompatible’ or ‘compatible’ (at least partially compatible) with current pharmacotherapeutic guide lines. In addition to this classification a treatment evaluation score was also applied to each study subject. This score was based on the use of anti-inflammatory therapy (oral and inhaled) in conjunction with the regular use of bronchodilators, as well as the use of oral corticosteroids for patients recently discharged from hospital foll owing an attack or asthma.

RESULTS: At least one of the two clinician reviewers judged therapy to be incompatible with current standards in 49% of the case patients compared with 20% of the subjects who had not experienced a life-threatening episode. The mean ± SD treatment score was 3.5±1.7 in cases compared with 0.8±1.4 in controls, suggesting quality or pharmacological treatment was worse in cases (P<0.001).

CONCLUSIONS: Pharmacological therapy incompatible with current recommendations was more common among cases of fatal and near fata l asthma in Saskatchewan from 1980 to 1987.