Environmental exposome and its public health impact on COPD and asthma exacerbations in France

Chronic obstructive pulmonary disease (COPD) and asthma exacerbations in France cause substantial morbidity, mortality, and healthcare costs. Although their occurrence is influenced by environmental and socioeconomic factors, nationwide analyses quantifying the impact of air pollution, climate extremes, and social deprivation are limited. Understanding these determinants is crucial to guide interventions and reduce the economic burden of these diseases.

We conducted a retrospective, population-based study using the French National Hospital Discharge PMSI database (period 2018-2022). Hospitalization records were linked with publicly available datasets capturing air pollutants (PM₂.₅, PM₁₀, NO₂, O₃), greenhouse gas emissions, meteorological variables, population density, land use, and socioeconomic deprivation indices. Exposures were assigned to patients based on their municipality of residence or, for time-varying factors, using the nearest monitoring station. 473,990 COPD and 187,332 asthma patients were matched for sex, birth year, and date of first hospitalization. Associations between environmental and socioeconomic exposures and exacerbation risk were evaluated using univariate conditional logistic regression. Population attributable fractions (PAFs) were subsequently calculated to quantify excess hospitalizations and estimate associated healthcare costs.

Poverty emerged as the primary factor driving higher healthcare costs, with annual incremental costs of €21.5 million for COPD (PAF 4.92%) and €9.5 million for asthma (PAF 18.83%). Air pollution effects differed by disease. PM₂.₅ and O₃ were mainly associated with COPD, with annual costs of €17 million (PAF 3.85%) and €18 million (PAF 4.06%), respectively. Greenhouse gases and NO₂ contributed to exacerbations in both conditions: greenhouse gases accounted for €9 million in COPD (PAF 2.11%) and €5.5 million in asthma (PAF 10.33%), while NO₂ costs were €13.5 million for COPD (PAF 3.04%) and €3.5 million for asthma (PAF 6.87%). Extreme temperatures generated €4 million in annual costs for COPD patients (PAF 0.88%). Annual expenditures for exacerbations attributable to high population density were €11 million for COPD (PAF 2.48%) and €7 million for asthma (PAF 13.70%).

This study underscores the critical contribution of the exposome to the economic burden of COPD and asthma exacerbations in France. Our findings provide an evidence-based framework for implementing targeted interventions addressing material deprivation, air pollution, and high population density, which can improve clinical outcomes while enhancing cost-efficiency in the healthcare system.