Impact of SARS-CoV-2 Infection on Pulmonary Function in the PURE-Colombia Cohort: A Comparative Analysis with Pre-COVID Values and Non-COVID-19 Controls

Background: The factors driving Coronavirus disease 2019 (COVID-19) severity and its long-term respiratory sequelae remain poorly understood. This study evaluates whether baseline lung function (LF) influences COVID-related clinical outcomes, mortality, and post-infection LF decline. Methods: Data from 602 participants in the Prospective Urban Rural Epidemiology (PURE)-Colombia study were analyzed. Among these, 200 with confirmed SARS-CoV-2 infection and 402 controls (65% women; 68% aged ≥60 years). All underwent baseline spirometry prior to 2010 and follow-up testing 1–40 months post-recovery. Among infected individuals, 51 (26%) died. Spirometric parameters Forced Expiratory Volume in 1 Second (FEV₁), Forced Vital Capacity (FVC), and Peak Expiratory Flow (PEF) were compared using paired t-tests and Cohen’s d. Non-parametric data were compared using Wilcoxon s (z statistic). Results: Compared to baseline LF, hospitalized COVID-19 patients showed significant declines in follow-up LF: FEV₁ (2.84 vs. 2.34 L; p = 0.002), FVC (3.01 vs. 2.53 L; p = 0.006), and PEF (399 vs. 328 L; p = 0.001). Non-hospitalized COVID-19 cases showed a non-significant downward trend, while controls maintained stable LF. Risk factors for post-COVID FEV₁ < 80% predicted included hospitalization, elevated waist-to-hip ratio, and incomplete or absent COVID-19 vaccination. Moderate-to-high physical activity was protective. Post-COVID PEF < 80% predicted was associated with female sex, diabetes mellitus, and subsidized healthcare enrollment. Mortality risk was elevated among individuals with low baseline LF, age > 65, male sex, hypertension, obesity, low physical activity, and reduced handgrip strength. Conclusions: Significant LF decline was observed in hospitalized COVID-19 patients, with minimal changes in outpatients and controls. Identifying clinical and demographic predictors of post-COVID LF impairment may inform targeted interventions to mitigate long-term pulmonary complications.