The economic and societal burden associated with Post-COVID in the Netherlands: a cost-of-illness and quality of life study protocol.

Post-COVID poses a substantial yet under-quantified burden on the Dutch healthcare system and labor market, lacking detailed data on societal costs and health-related quality of life (HRQOL). This study outlines a cross-sectional, prevalence-based, bottom-up design aimed at mapping individual patient costs and the impact of HRQOL within the Netherlands. Patient data will be further stratified according to context-specific factors such as disease severity and symptom clusters if sufficient data is available. The study collects individual resource-use, productivity and HRQOL data by self-report. Adult (≥18 years) respondents with Post-COVID are recruited nationally via patient platforms and the Post-COVID Network Netherlands (PCNN). The target sample for the quantitative component is ~400 respondents to provide robust descriptive cost and HRQOL estimates and exploratory subgroup descriptions. Resource use is measured primarily with the adapted versions of iMTA Medical Consumption Questionnaire (iMCQ) and iMTA Productivity Cost Questionnaire (iPCQ) and valued using Dutch reference unit prices. HRQOL is measured using the EQ-5D-5 L, applying the Dutch tariff. The study results will describe the economic impact of Post-COVID, focusing on cost-of-illness (€) and HRQOL (utilities) in the Netherlands. The study follows national data-protection procedures and aims to inform policy, care organization and future economic evaluations.