COVID19-related and all-cause mortality among middle-aged and older adults across the first epidemic wave of SARS-COV-2 infection in the region of Tarragona, Spain: results from the COVID19 TARRACO Cohort Study, March-June 2020.

Background: Direct and indirect COVID19-related mortality is uncertain. This study investigated COVID19-related and all-cause deaths among middle-aged and older adults during the first wave of COVID19 epidemic period, assessing mortality risks by pre-existing socio-demographic and medical underlying conditions. Methods: Population-based cohort study involving 79,083 individuals ≥50 years-old in Tarragona (Southern Catalonia, Spain). Baseline cohort characteristics (age/sex, comorbidities and medications/vaccinations history) were established at study start (01/03/2020) and main outcomes were COVID19-related deaths (occurred in patients diagnosed with the disease) and all-cause deaths occurred among cohort members between 01/03/2020-30/06/2020. Mortality risks were assessed by Cox regression analyses. Results: Cohort members were followed for 1,356,358 persons-weeks, occurring 576 all-cause deaths (124 COVID19-related). All-cause mortality rate was 42.5 deaths per 100,000 persons-week, being 22.8 in healthy/unrelated-COVID19 subjects, 236.4 in COVID19-excluded/PCR-negative subjects, 493.7 in COVID19-compatible/PCR-unperformed subjects and 4009.1 in COVID19-confirmed patients. In multivariable analyses, increasing age, sex male, nursing-home residence, cancer, neurologic, cardiac or liver disease, receiving diuretics, systemic corticosteroids, proton-pump inhibitors and benzodiazepines were associated with increased risk of all-cause mortality; conversely, receiving renin-angiotensin inhibitors and statins were associated with reduced risk. Age/years, sex male and nursing-home residence were strong predictors for COVID19-related mortality, but none comorbidity appeared significantly associated with an increased risk. Conclusion: Apart from direct COVID19-related deaths (which represented almost 22% of all-cause mortality), theoretically COVID19-excluded patients (PCR-negative) suffered considerable greater all-cause mortality than healthy/unrelated-COVID19 subjects, which could explain, in part, the large excess deaths observed across the COVID19 pandemic.