Health care education, delivery, and quality
Characteristics and medical resource use of asthmatic subjects with and without work-related asthma

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Background

Asthma is work related when there is an association between symptoms and work. Occupational asthma (OA) is induced by the workplace, whereas work-exacerbated asthma (WEA) is triggered by the workplace but not induced by it.

Objective

We sought to compare the clinical characteristics and the use of medical resources between subjects with work-related asthma (WRA) and asthmatic control subjects without WRA, as well as between subjects with OA and subjects with WEA.

Methods

We performed a retrospective cohort study of the charts of subjects with WRA who were investigated between 2001 and 2004 in our centers. These subjects were matched according to sex, age, and FEV1 to subjects with non–WRA investigated during the same period. All charts were linked to the information provided by the Régie de l'assurance maladie du Québec, including outpatient clinic visits and visits to the emergency department and hospitalizations during the year before and after the initial assessment in our centers.

Results

Three hundred fifty-one subjects had WRA (WEA, 145; OA, 206), whereas 384 subjects were asthmatic control subjects without WRA. Subjects with WRA had more asthma exacerbations than subjects with non-WRA. The risk factor of experiencing a severe asthma exacerbation was no greater for OA than for WEA (odds ratio, 1.15; 95% CI, 0.75-1.75).

Conclusion

WRA is associated with a larger use of medical resources than non-WRA.

Clinical implications

Improving the diagnosis and management of WRA is crucial for limiting the use of medical resources associated with this condition.

Section snippets

Study design

A retrospective cross-sectional study of all the charts of subjects who were investigated for suspected WRA by means of specific inhalation challenge (SIC) tests between 2001 and 2004 was undertaken at Sacré-Coeur Hospital and Laval Hospital in the Canadian province of Quebec. The charts of asthmatic control subjects without WRA investigated during the same period were matched according to sex, age categories (younger or older than 45 years), and FEV1 categories (lower than 50% of predicted

Results

A total of 897 charts were reviewed. Five hundred thirteen subjects were investigated for WRA during a 3-year period. Three hundred fifty-one subjects had WRA: 145 had WEA, and 206 had OA. Three subjects who were given diagnoses of RADS were not included in the WRA or control groups, as mentioned in the definition section. One hundred sixty-two subjects did not have asthma at the time of the investigation. The repartition of the various diagnoses is shown in Fig 1.

Three hundred eighty-four

Discussion

This study showed that WRA is associated with a greater use of medical resources than NWRA. Indeed, subjects with WRA visited their physicians more frequently because of their asthma, went more frequently to the emergency department, and were more frequently hospitalized than asthmatic subjects without WRA for a similar level of airflow obstruction and airway responsiveness.

Our study is consistent with the findings from Breton et al,6 who reported that subjects with WRA were more likely to

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Supported by the Asthma in the Workplace Center, CIHR. Catherine Lemiere and Lucie Blais hold a scholarship from the Canadian Institutes of Health Research (CIHR).

Disclosure of potential conflict of interest: L.-P. Boulet has consulting arrangements with Altana, AstraZeneca, GlaxoSmithKline, Novartis, and Merck Frosst and has received grant support and is on the speakers' bureau for 3M, Altana, Asthmatx, AstraZeneca, Boehringer Ingelheim, Dynavax, Genentech, GlaxoSmithKline, IVAX, Merck Frosst, Novartis, Pfizer, Roche, Schering, and Topigen.

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