Lung function in patients with lung injury due to household chemical inhalation: Post hoc analysis of a prospective nationwide cohort.

BACKGROUND AND OBJECTIVE: Inhalation exposure to household chemicals can result in serious health problems, although the long-term outcomes are unclear. We evaluated the changes in lung function after home humidifier disinfectant (HD) exposure.

METHODS: This post hoc analysis of a prospective nationwide cohort involved patients with inhalation lung injury due to HD. Patients underwent spirometric measurements at onset and annually thereafter.

RESULTS: Forty subjects met the eligibility criteria. Overall, mean forced vital capacity (FVC) increased significantly during the first 3 years from 2.10 ± 0.74 to 3.06 ± 1.08 L. Mean forced expiratory volume in 1 s (FEV1 ) also rose from 1.84 ± 0.63 to 2.62 ± 0.88 L. Both variables then stabilized. However, in 19 (48%) patients, the FVCs did not normalize. Compared to subjects with an FVC at onset of <2.5 L, subjects with onset FVC ≥2.5 L exhibited significantly more improvement in percent predicted FVC over time (group × time interaction: P < 0.001). Patients with lower exposure also exhibited increasing percent predicted FVC over time, whereas more exposed patients showed a plateau starting at year 1. On multivariate analysis, onset FVC < 2.5 L associated significantly with <80% predicted FVC at year 4 (adjusted OR: 20.33; 95% CI: 1.10-376.53; P = 0.04).

CONCLUSION: Half of the patients with inhalation injury exhibited stabilization of lung function within several years of onset. However, lung function was impaired in the remaining patients. This impairment associated with lung function at onset and exposure intensity.