Changing Role of Comorbidities in Risk of Mortality Among Elderly Patients Diagnosed with COVID-19 in the United States: Examining Pre- and Post-Vaccine Clinical Risk Factors

OBJECTIVES: COVID-19 pandemic resulted in over a million deaths in the US; with the first wave being particularly impactful in terms of negative health outcomes among older Americans. Older age was identified as a significant risk factor for mortality. However, little is known about the role played by comorbidities in deaths during subsequent waves after availability of vaccines. The objective of this study is to examine the differences in the association between comorbidities and mortality among patients treated for COVID-19 over time.

METHODS: Over 4.1 million elderly patients (aged ≥65 years) had a claim with COVID-19 diagnosis between 4/1/2020 and 4/30/2022 in IQVIA longitudinal medical and pharmacy claims databases. Demographic and clinical characteristics were reported. Logistic regression models examined the association of Chain-of-event (COE) and significant-contributing conditions (SCC) with mortality before and after availability of COVID-19 vaccine.

RESULTS: Between 4/1/2020 and 12/31/2020 (pre-vaccine), of 1,441,278 elderly patients with COVID-19 diagnosis, 215,094 (14.92%) were confirmed dead. Between 1/1/2021 and 4/30/2022 (post-vaccine=after the first vaccine was available), of 2,758,100 elderly patients with COVID-19 diagnosis, 237,793 (8.62%) died. After controlling for sociodemographic factors, COE including cardiac arrest (pre-vaccine OR: 2.023 [95% CI:1.948-2.101]; post-vaccine OR: 3.105[CI:3.009-3.205]) and acute respiratory distress syndrome (pre-vaccine OR: 1.792 [CI:1.746-1.840]; post-vaccine OR:2.478[95% CI:2.420-2.537]) had higher odds of mortality during the post-vaccine period. Neurological SCC including Alzheimer’s disease (pre-vaccine OR: 1.388 [CI:1.367-1.409]; post-vaccine OR: 1.413 [CI:1.388-1.438]) and dementia (pre-vaccine OR:1.476 [CI: 1.458-1.494]; post-vaccine OR:1.568;[CI:1.548-1.589]) as well as cardiac SCC including atrial fibrillation (pre-vaccine OR:1.274 [CI: 1.260-1.288]; post-vaccine OR:1.338;[CI:1.324-1.352]) and congestive heart failure (pre-vaccine OR:1.302 [CI: 1.287-1.317]; post-vaccine OR:1.362;[CI:1.347-1.377]) also had higher odds during post-vaccine period.

CONCLUSIONS: Our findings indicate higher odds associated with certain COE and SCC after vaccine availability. Previously unknown factors, like Alzheimer’s disease and dementia, emerged as risk factors for death among elderly patients with COVID-19 infection.