Examining potential Long COVID effects through utilization of healthcare resources: a retrospective, population-based, matched cohort study comparing individuals with and without prior SARS-CoV-2 infection

Background: A significant proportion of individuals reports persistent clinical manifestations following SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) acute infection. Nevertheless, knowledge of the burden of this condition-often referred to as 'Long COVID'-on the health care system remains limited. This study aimed to evaluate healthcare utilization potentially related to Long COVID.

Methods: Population-based, retrospective, multi-center cohort study that analyzed hospital admissions and utilization of outpatient visits and diagnostic tests between adults aged 40 years and older recovered from SARS-CoV-2 infection occurred between February 2020 and December 2021 and matched unexposed individuals during a 6-month observation period. Healthcare utilization was analyzed by considering the setting of care for acute SARS-CoV-2 infection [non-hospitalized, hospitalized and intensive care unit (ICU)-admitted] as a proxy for the severity of acute infection and epidemic phases characterized by different SARS-CoV-2 variants. Data were retrieved from regional health administrative databases of three Italian Regions.

Results: The final cohort consisted of 307 994 previously SARS-CoV-2 infected matched with 307 994 uninfected individuals. Among exposed individuals, 92.2% were not hospitalized during the acute infection, 7.3% were hospitalized in a non-ICU ward and 0.5% were admitted to ICU. Individuals previously infected with SARS-CoV-2 (vs. unexposed), especially those hospitalized or admitted to ICU, reported higher utilization of outpatient visits (range of pooled Incidence Rate Ratios across phases; non-hospitalized: 1.11-1.33, hospitalized: 1.93-2.19, ICU-admitted: 3.01-3.40), diagnostic tests (non-hospitalized: 1.35-1.84, hospitalized: 2.86-3.43, ICU-admitted: 4.72-7.03) and hospitalizations (non-hospitalized: 1.00-1.52, hospitalized: 1.87-2.36, ICU-admitted: 4.69-5.38).

Conclusions: This study found that SARS-CoV-2 infection was associated with increased use of health care in the 6 months following infection, and association was mainly driven by acute infection severity.