Associations of COVID-19 diagnosis with levels of selected clinical markers among elderly individuals: a hospital-based, cross-sectional study

Abstract: Background Coronavirus Disease-2019 (COVID-19) affected elderly individuals disproportionately in terms of hospitalization and adverse outcome. Objective This cross-sectional study examined the associations of COVID-19 diagnosis (COVID-negative versus COVID-positive) with levels of four clinical markers – cardiac troponin T (cTnT), high-sensitive C-reactive protein (hsCRP), D-dimer and b-type natriuretic peptide (NT-proBNP) – along with potential differences in associations by sex in a hospital-based sample of elderly individuals. Methods The sample comprised individuals aged ≥80 years visiting the Emergency at Karolinska universitetssjukhuset (Huddinge) between January 2020 and December 2021 for whom data on polymerase chain reaction-based COVID-19 testing were available (n=2668). Plasma levels of the markers were measured using standard methods. Right skewed outcome variables were natural-log (Ln) transformed. Multivariable linear regression models were fitted. Results Participants’ median age was 87 years (interquartile range: 85–90) and 58.4% were female. Approximately 13% of the participants were COVID-19 positive. There was no statistically significant association between COVID-positive diagnosis and any of the markers after controlling for age and sex. On sex stratification, COVID-19 positive males had 55.3% (95% confidence interval (CI): 1.1%–138.4%; P=0.044) higher hsCRP levels than COVID-negative males. Additionally, age was positively associated with cTnT (Ln cTnT βadjusted: 0.041; 95% CI: 0.033–0.050; P<0.001) and NT-proBNP (Ln NTproBNP βadjusted: 0.059; 95% CI: 0.015–0.102; P=0.008). Conclusion COVID-positive diagnosis was not related with the markers apart from a sex-specific, positive association with hsCRP observed among males. Future studies should explore the relationship of these markers with mortality to determine their prognostic utility among elderly individuals.