Persistent asthma, comorbid conditions and the risk of work disability: a prospective cohort study

This study examined whether asthma alone or together with chronic comorbidity is associated with an increased risk of long-term work disability.

We examined data from 2332 asthmatic and 66 354 nonasthmatic public sector employees in Finland who responded to a survey between 1997 and 2004. Respondents were coded as persistent asthmatics based on the special reimbursement for continuous asthma medication by the Social Insurance Institution. Data on long-term work disability (sickness absences or disability pensions > 90 days) were obtained from national registers. The risk of work disability was examined by Cox proportional hazard models adjusted for age, gender, socioeconomic status, type of employment contract, and type of employer.

Asthma increased the risk of all-cause long-term work disability with hazard ratio (HR) 1.8 (95% CI 1.62-2.09) compared with controls (no asthma). Asthma and one other chronic comorbidity increased the risk of long-term all-cause work disability with HR 2.2 (95% CI 1.78-2.83). Asthma together with two or more other chronic conditions increased the risk with HR 4.5 (95% CI 2.98-6.78). Asthma and depression increased the risk with HR 3.6, and the risk was especially high for permanent work disability (HR 6.8). Among those with asthma, there were more women, obese individuals (BMI ≥ 30), ex-smokers, and lower-grade nonmanual workers.

Asthma is associated with an increased risk of long-term all-cause work disability. The risk increases further with chronic comorbidities and is especially high in patients with asthma and depression.