Long-term health effects of COVID-19 among patients in Croatian primary care settings

Branislava Popović; Ana Lesac Brizić; Aleksandar Ljubotina; Tina Zavidić; Vedrana Tudor Špalj; Roberta Marković Štimac; Martina Fišić Jurković; Nina Bašić Marković; Ines Diminić Lisica; Jasna Vučak; Nives Radošević Quadranti

doi:10.3389/fmed.2026.1740432

Long-term health effects of COVID-19 among patients in Croatian primary care settings

Front Med (Lausanne). 2026 Jan 29:13:1740432. doi: 10.3389/fmed.2026.1740432. eCollection 2026.

Authors

Branislava Popović^{1

2}, Ana Lesac Brizić^{1

3}, Aleksandar Ljubotina^{1

4}, Tina Zavidić^{1

5}, Vedrana Tudor Špalj^{1

3}, Roberta Marković Štimac^{1

6}, Martina Fišić Jurković^{1

3}, Nina Bašić Marković^{1

6}, Ines Diminić Lisica^{1

7}, Jasna Vučak^{1

8}, Nives Radošević Quadranti^{1

3}

Affiliations

¹ Department of Family Medicine, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.
² Family Medicine Practice Branislava Popović, Rijeka, Croatia.
³ Community Health Centre Primorsko Goranska County, Rijeka, Croatia.
⁴ Family Medicine Practice Aleksandar Ljubotina, Rijeka, Croatia.
⁵ Istrian Health Centres, Pazin, Croatia.
⁶ Primary Health Care Institution Srdoči, Rijeka, Croatia.
⁷ Health Institution dr. Ines Diminić Lisica, Rijeka, Croatia.
⁸ Family Medicine Practice Jasna Vučak, Sukošan, Croatia.

Abstract

Introduction: The COVID-19 pandemic has left lasting effects that extend beyond the acute phase of infection, with increasing evidence of long-term health consequences. This study aimed to assess the prevalence of post-COVID symptoms and conditions and to identify associated risk factors, including pre-existing chronic diseases, COVID-19 vaccination status, and severity of acute infection.

Methods: This retrospective cross-sectional study was conducted in 10 family medicine practices in Croatia. The data collected from medical records included demographics, COVID-19 vaccination status, SARS-CoV-2 infection history and severity, and documented health conditions before and after infection. Descriptive statistics were used to summarize the data. Group differences were analyzed using the independent samples t-test or χ² test. Variables significant in univariate analyses (p < 0.05) were included into multivariate regression models. Multiple linear regression was used to identify predictors of COVID-19 severity, and binary logistic regression was applied to determine factors associated with post-COVID conditions. Results are presented as regression coefficients (β) or odds ratios (OR) with 95% confidence intervals (CI). A p-value < 0.05 was considered statistically significant.

Results: The study included 1,423 participants (58.0% female; mean age 52.6 ± 17.2 years), of whom 82.4% had confirmed SARS-CoV-2 infection and 32.3% were unvaccinated. At least one chronic disease was present in 28.1% of participants. The most frequently reported post-COVID conditions were brain fog (4.9%), neurological disorders (4.7%), cardiovascular diseases (2.9%), shortness of breath (2.8%), obesity (2.7%) and mental health disorders (2.6%). Greater COVID-19 severity was independently associated with pulmonary disease (β = 0.22; p = 0.031) and older age, particularly 51-65 years (β = 0.31; p < 0.001) and ≥66 years (β = 0.50; p < 0.001). COVID-19 vaccination was associated with milder disease (β = -0.21; p < 0.001). Previous cardiovascular and musculoskeletal diseases significantly increased the risk of thromboembolism. Diabetes, obesity, and number of vaccine doses were predictors of brain fog, while neurological comorbidities predicted post-COVID mental health disorders.

Conclusion: Post-COVID symptoms and conditions represent an important long-term public health challenge. Family medicine physicians play a key role in early recognition, monitoring, and management of post-COVID sequelae, contributing to improved long-term patient outcomes.

Keywords: COVID-19; SARS-CoV-2; chronic diseases; long COVID; post-COVID syndrome; primary care.