Background: The seasonal variation of influenza and influenza-like illness (ILI) is well known. However, studies assessing the factual direct costs of ILI for an entire population are rare.
Methods: In this register study, we analyzed the seasonal variation of ILI-related healthcare visits and hospital admissions for children aged 2 to 17 years, and the resultant parental absence from work, for the period 2005 to 2012. The study population comprised an open cohort of about 78,000 children per year from a defined region. ILI was defined as ICD-10 codes: J00-J06; J09-J15, J20; H65-H67.
Results: Overall, the odds of visiting a primary care center for an ILI was 1.64-times higher during the peak influenza season, compared to the preinfluenza season. The corresponding OR among children aged 2 to 4 years was 1.96. On average, an estimated 20% of all healthcare visits for children aged 2 to 17 years, and 10% of the total healthcare costs, were attributable to seasonal ILI. In primary care, the costs per week and 10,000 person years for ILI varied - by season - from &OV0556;3500 to &OV0556;7400. The total ILI cost per year, including all physical healthcare forms, was &OV0556;400,400 per 10,000 children aged 2 to 17 years. The costs for prescribed and purchased drugs related to ILI symptoms constituted 52% of all medicine costs, and added 5.8% to the direct healthcare costs.The use of temporary parental employment benefits for caring of ill child followed the seasonal pattern of ILI (r = 0.91, P < 0.001). Parental absence from work was estimated to generate indirect costs, through loss of productivity of 5.2 to 6.2 times the direct costs.
Conclusions: Direct healthcare costs increased significantly during the influenza season for children aged 2 to 17 years, both in primary and hospital outpatient care, but not in hospital inpatient care. Primary care manages the majority of visits for influenza and ILI. Children 2 to 4 years have a larger portion of their total healthcare encounters related to ILI compared with older children. There is a clear correlation between ILI visits across the years and parental absence from work.