Estimating work-related indirect costs in allergic rhinitis and asthma using a daily combined symptom-medication score: a MASK-air® study in collaboration with the EAACI Methodology Committee

BACKGROUND: Allergic rhinitis and asthma can impair work productivity. OBJECTIVE: To validate a daily work productivity visual analog scale (VAS work), comparing it with the Work Productivity and Activity Impairment Questionnaire plus Classroom Impairment Questions: Allergy Specific (WPAI+CIQ:AS). We also aimed to quantify how allergy control relates to work impairment and indirect costs. METHODS: We conducted a cross-sectional study using data from the MASK-air® app. Patients recorded daily VAS and weekly WPAI+CIQ:AS responses. We calculated correlations between VAS work and WPAI+CIQ:AS outcomes. Mixed-effects regression models assessed associations between disease control, measured by the Combined Symptom-Medication Score (CSMS) and the electronic daily asthma control score (e-DASTHMA), and VAS work. Indirect costs were estimated using the human capital approach, applying VAS-based productivity losses to country-specific wage distributions. RESULTS: VAS work correlated strongly with the WPAI+CIQ:AS, with Spearman coefficients ≥0.70 for total work impairment and presenteeism. Each 1-point increase in CSMS and e-DASTHMA was associated with mean 0.97 and 0.79-point increases in VAS work, respectively. In poorly controlled days, the estimated daily indirect cost based on CSMS ranged from 12.50 US$ PPP (P25-P75=5.60-26.70) in Brazil to 129.90 US$ PPP (P25-P75=80.40-199.40) in Iceland. Based on e-DASTHMA, daily estimates ranged from 9.30 US$ PPP (P25-P75=3.70-21.50) in Brazil to 101.90 US$ PPP (P25-P75=51.20-172.40) in Iceland. CONCLUSION: VAS work is a valid simple daily measure of work impairment due to rhinitis and asthma. CSMS and e-DASTHMA can be used to estimate productivity losses attributable to poor disease control.