Abstract
BACKGROUND: Seasonal influenza vaccination coverage in Italian older adults is insufficient and well below the minimum target of 75%. In Italy, most influenza vaccine doses are administered by general practitioners (GPs), whose number has been declining. In parallel, the number of patients per GP and GP workload increased dramatically, which theoretically may impair vaccination counselling. In this ecological study, we aimed to assess whether influenza vaccination coverage in older adults is associated with the density of GPs having high number of patients. METHODS: The study outcome was the influenza vaccination coverage rate in adults aged ≥ 65 years and registered in 20 Italian regions over the last 23 years. The independent variable of interest was the proportion of GPs with more than 1,500 adult patients, which is an imposed normative ceiling. This latter variable was considered as a proxy of GP overload. By adopting a panel regression approach, different specifications of fixed- and random-effects models were run to assess the association of interest, when adjusted for several social structural, economic and healthcare-related variables. RESULTS: Over the last two decades, most regions showed a negative association between influenza vaccination coverage rates and the density of GPs with a high number of patients. This latter negative association was confirmed (P < 0.05) in different panel model specifications. In particular, in the fully adjusted two-way fixed-effects model, each 10% increase in the number of GPs with more than 1,500 patients was associated with a 1.7% decrease in influenza vaccination coverage. However, this association was present only in region-years where at least 18% of GPs were deemed overloaded. CONCLUSIONS: In the upcoming years, the number of Italian GPs is projected to decline further. At the same time, the aging Italian population will determine an even greater workload for GPs. This study demonstrated that increased GP workload may partially explain the spatiotemporal variation in influenza vaccination uptake in the Italian elderly. With the imperative of increasing or at least maintaining influenza vaccination coverage rates, several short- and mid-term initiatives should be implemented in order to optimize GP workload during seasonal immunization campaigns.