Clinical and economic burden of physician-diagnosed influenza in adults during the 2017/2018 epidemic season in Spain

Abstract

Background Influenza is an acutely debilitating respiratory infection, contributing significantly to outpatient visits and hospitalizations. Spain lacks comprehensive and updated data on the burden of influenza, particularly in the outpatient setting. Our study aimed to fill this gap by estimating the clinical and economic burden of physician-diagnosed influenza cases in adults from four Spanish regions, stratified by age groups and presence of comorbidities. Methods A retrospective cost-of-illness study was conducted using data from an electronic medical records database from the National Healthcare Service (NHS) of four Spanish regions for individuals aged ≥ 18 years diagnosed for influenza during the 2017/2018 epidemic season. Health resource utilization and related cost data were collected, including primary care visits, referrals to other specialists, visits to the emergency department, hospitalizations, and prescribed medicines. Results The study reported a total of 28,381 patients aged ≥ 18 years diagnosed with influenza, corresponding to 1,804 cases per 100,000 population. Most patients were aged < 65 years: 60.5% (n = 17,166) aged 18–49 and 26.3% (n = 7,451) 50–64 years. A total of 39.2% (n = 11,132) of patients presented a comorbidity. Cardiovascular diseases were the most common comorbidity reported along with influenza. The mean healthcare cost per case was estimated at €235.1 in population aged 18–49 years, increasing by 1.7 and 4.9 times in those aged 50–64 (€402.0) and ≥ 65 (€1,149.0), respectively. The mean healthcare cost per case was 3.2 times higher in patients with comorbidities. The total healthcare cost of medically attended influenza cases was mainly driven by primary care (45.1%) and hospitalization (42.0%). Patients aged 18–64 years old accounted for 61.9% of the costs of medically attended influenza. Irrespective of age, patients with comorbidities accounted for 67.1% of costs. Conclusions Season 2017/2018 was associated with a considerable burden of influenza in Spain, which increased with age and presence of comorbidities. Individuals with comorbidities accounted for most of the costs of influenza. Results suggest that population aged 18–64 years old is generating the highest share of costs to the NHS when all healthcare costs are considered. Preventive strategies targeting subjects with comorbidities, regardless of age, should be warranted.

Excess hospitalizations and mortality associated with seasonal influenza in Spain, 2008–2018

“…Indirect costs of lost productivity (from patients or their parents) and the medium and long-term costs related to the posterior treatment of complications caused or aggravated by influenza were not computed. Published studies for Spain report that hospitalization costs represent less than half of the total direct costs of influenza (with its weight varying according to patients’ age and comorbidities status), reflecting the importance of considering the burden in other settings of care [ 20 , 23 ].…”

“…The Burden of Acute Respiratory Infections (BARI) is a real-world evidence study assessing the clinical and economic burden of acute respiratory infections (influenza and respiratory syncytial virus) in Spain and Portugal [ 23 – 26 ]. We are reporting the results for the burden of severe influenza in Spain, measured through hospitalizations and deaths.…”

Addressing influenza’s underestimated burden – Iberian experts call to action

“…Results have been published for Spain and Portugal [ 14 , 15 ]. Complementarily, an electronic medical records (EMR) database from four Spanish regions during one season (2017/18) was analysed, shedding light on the direct healthcare burden of medically attended influenza, beyond hospitalization and using longitudinal health care data [ 16 ].…”

“…Estimates are conservative as they consider only NHS hospitalizations. The analysis of EMR from four Spanish regions has found evidence that population aged between 18 and 64 years old generated the highest share of costs to the NHS (61.9%) when all healthcare cost were considered, and not only hospitalization [ 16 ]. Individuals with comorbidities accounted for most of the costs (67.1%), regardless of age [ 16 ].…”

Impact of influenza related hospitalization in Spain: characteristics and risk factor of mortality during five influenza seasons (2016 to 2021)

“…At least four recent studies in Spain have used the national hospital discharge database, which records information on all hospitalized patients. Specifically, ( 4 ) studied inpatient hospital fatality related to influenza from 2009 to 2015; ( 5 ), the clinical and economic burden of physician-diagnosed influenza in adults during the 2017–2018 epidemic season; ( 6 ), excess hospitalizations and mortality associated with seasonal influenza from 2008 to 2018; and ( 7 ), the impact of respiratory syncytial virus and influenza virus infections in adults from 2012 to 2020.…”