Hospital-Based COVID-19 Surveillance in the Context of National and Global Pandemic Trends: A Retrospective Study of Demographic and Temporal Patterns

Background: Institutional COVID-19 testing patterns may differ from population-level trends owing to differences in testing practices, case ascertainment, and demographic composition. Retrospective evaluation of these patterns may provide insights into future surveillance of infectious diseases. This study aimed to characterise the demographic and temporal patterns of COVID-19 at TOBB University of Economics and Technology Faculty of Medicine Hospital and to contextualise these patterns within contemporaneous surveillance data from Turkey, the WHO European Region, and globally. Methods: In this retrospective descriptive study, SARS-CoV-2 reverse transcription polymerase chain reaction records from the hospital and aggregate World Health Organization surveillance data were evaluated from September 2020 to November 2022. Hospital data were evaluated according to age, sex, test positivity, and calendar month. Test positivity rates with 95% confidence intervals (CIs) were calculated, and sex-specific positivity rates were compared using Pearson’s chi-square test. Monthly hospital values were compared with the corresponding monthly national values for Turkey using Spearman’s rank correlation. Results: Among 49,318 SARS-CoV-2 reverse transcription polymerase chain reaction test results taken from the hospital data, 4810 were positive (9.75%; 95% CI: 9.49–10.01%). Test positivity did not differ between females and males (9.86% vs. 9.65%, p = 0.43). Adults aged 30–39 years represented the largest proportion of reported cases in the hospital (27.03%), Turkey (20.28%), the WHO European Region (16.48%), and globally (18.11%), whereas hospital testing was concentrated among adults aged 20–59 years. Hospital case counts peaked in November 2020 and February 2022, with the latter coinciding with the major COVID-19 surge in early 2022 in broader surveillance data. Monthly hospital case counts were positively correlated with monthly national case counts for Turkey (Spearman rho = 0.55, p = 0.003). Conclusions: Hospital-based surveillance identified major demographic and temporal features of the pandemic. However, differences in testing populations, case ascertainment, and reporting practices limit direct comparisons. Integrating institutional- and population-level data may strengthen surveillance frameworks for future respiratory infectious disease outbreaks.