Key Secular Trends During Three Waves of the COVID-19 Pandemic

Importance: Patient age, comorbidity burden, and severity are the major factors associated with surviving COVID-19. Hospital-level factors including ICU occupancy may confer additional risk to individual patients, particularly at times of maximal stress on healthcare systems. The interaction of patient- and hospital-level factors over time during pandemic disease remains an area of active exploration. Objective: To determine the impact of patient and hospital risk factors during episodic surges, characterize severity distribution between waves, and evaluate patient-level impact of ICU capacity on COVID-19 survivorship.Design: Retrospective cohort study.Setting: Four acute care hospitals within an integrated healthcare network in San Diego, California.Participants: All patients (18+ y.o.) admitted with a positive PCR test for SARS-CoV-2 or ICD-10 code for COVID-19 from March 1, 2020 thru June 30, 2020.Main Outcome(s) and Measure(s): patient survivorship and length of stay.Results: 6,851 patients were evaluated in this large cohort series. Patient level factors associated with mortality included: severity at admission, age, gender, BMI, martial status, language preference, Elixhauser score, elevated laboratory (d-dimer, ferritin, LDH) or lower absolute lymphocyte count. When adjusting for patient age alone, survivorship during surges was also inversely associated with ICU occupancy, though this correlation was not present when adjusted for patient-level factors.Conclusions and Relevance: Patient age, comorbidity burden, and severity at the time of presentation are the major factors associated with surviving COVID-19. Hospital-level factors including ICU occupancy may confer additional risk to individual patients, particularly at times of maximal stress on healthcare systems.