Long-Term Prognosis of Work-Related Asthma After Specific Inhalation Challenge

Few studies have assessed the long-term prognosis of work-related asthma (WRA).

We evaluated outcomes in WRA patients after specific inhalation challenge (SIC), including remission rates and factors associated with poor outcomes. Patients with positive SIC received the diagnosis of having occupational asthma.

We sent a follow-up questionnaire to 618 patients with WRA. Difficult-to-treat asthma was defined as poor symptom control, two or more asthma exacerbations, or one or more serious exacerbation within a year despite treatment with Global Initiative for Asthma Steps 4 to 5 asthma medication. Clinical asthma remission off-treatment was defined as no symptoms, exacerbations, or medication within a year.

Altogether 274 patients with WRA (44%) responded a median of 8.5 years after SIC; 110 had a positive SIC reaction and 164 a negative reaction. Among responders, 216 (79%) reported no current exposure to the suspected causal agent, and 173 of working-age patients (75%) reported being employed. Seventy patients with positive SIC (67%) and 75 with negative SIC (47%) result had changed their occupations (P = .002). Eighty-seven (32%) had difficult-to-treat asthma, and 12 (4%) had clinical asthma remission off-treatment, with no significant differences between SIC-positive and negative groups. Factors predicting difficult-to-treat asthma at follow-up included age 45.8 years and older (adjusted odds ratio [OR] = 2.10; 95% CI, 1.19-3.70), Asthma Control Test score less than 20 (OR = 2.02; 95% CI, 1.13-3.61), Global Initiative for Asthma Steps 4 to 5 medication (OR = 3.10; 95% CI, 1.68-5.71), and difficult-to-treat asthma (OR = 5.73; 95% CI, 2.66-12.35) at diagnosis.

Long-term outcomes are largely comparable in patients with WRA regardless of SIC results. Clinical asthma remission is rare. Patients with poorly controlled asthma at diagnosis require close follow-up and support.