Direct cost of occupational asthma and associated factors in the private sector in central Tunisia

Occupational asthma (OA) is a significant public health concern due to its high prevalence and socioeconomic burden. In Tunisia, direct costs of OA have not been previously evaluated, highlighting an important knowledge gap for health policy planning. This study aimed to assess the direct cost of OA in the private sector of central Tunisia and identify factors influencing this cost.

A retrospective claims-based cohort study was conducted using data from the National Health Insurance Fund (CNAM) on OA cases recognised between 2015 and 2017 in the governorates of Sousse, Monastir, Mahdia and Kairouan, central Tunisia. Direct costs were estimated from the CNAM payer perspective. The costs were tracked from the date of recognition until 31 December 2020 and expressed in 2020 Tunisian dinars (TND). Statistical analyses included univariate tests and generalized linear models (GLM) with gamma family and log link for right-skewed cost data, reporting adjusted incidence rate ratios (aIRR) with Huber-White (HC1) robust standard errors.

A total of 157 cases of OA were analyzed, predominantly female (75.8%), with a mean age of 43.41 ± 7.29 years. The textile sector represented 72% of cases. High-molecular weight allergens, particularly vegetable textile dust (70.7%), were the agents most frequently implicated. The median total direct cost was 4,593.52 TND (€1,467.24) per case [IQR: 3,408.00-6,871.72]. The median annualized cost was 1,114.03 TND (€355.94) per person-year. Cash benefits (96.8% of patients) dominated over in-kind benefits (22.9%). In multivariate analysis, age ≥ 40 years was the only significant independent predictor of medical costs (adjusted incidence rate ratio [aIRR] = 2.84, 95% CI: 1.59-5.07; p < 0.001), whereas no clinical or demographic factor predicted indemnity costs. Univariate analysis additionally identified male sex (p = 0.04), higher PPD rate (p < 0.001), and absence of prior occupational disease history (p = 0.001) as factors associated with higher total direct costs.

This study highlights the considerable direct costs associated with occupational asthma in central Tunisia's private sector, and the resulting burden placed on the healthcare system and the affected workforce. These findings underscore the need to strengthen primary prevention strategies, particularly in the textile industry, to reduce both the health and economic impact of this disease.