Incidence, clinical outcomes, and transmission dynamics of severe coronavirus disease 2019 in California and Washington: prospective cohort study

Abstract

ObjectiveTo understand the epidemiology and burden of severe coronavirus disease 2019 (covid-19) during the first epidemic wave on the west coast of the United States.DesignProspective cohort study.SettingKaiser Permanente integrated healthcare delivery systems serving populations in northern California, southern California, and Washington state.Participants1840 people with a first acute hospital admission for confirmed covid-19 by 22 April 2020, among 9 596 321 healthcare plan enrollees. Analyses of hospital length of stay and clinical outcomes included 1328 people admitted by 9 April 2020 (534 in northern California, 711 in southern California, and 83 in Washington).Main outcome measuresCumulative incidence of first acute hospital admission for confirmed covid-19, and subsequent probabilities of admission to an intensive care unit (ICU) and mortality, as well as duration of hospital stay and ICU stay. The effective reproduction number (RE) describing transmission dynamics was estimated for each region.ResultsAs of 22 April 2020, cumulative incidences of a first acute hospital admission for covid-19 were 15.6 per 100 000 cohort members in northern California, 23.3 per 100 000 in southern California, and 14.7 per 100 000 in Washington. Accounting for censoring of incomplete hospital stays among those admitted by 9 April 2020, the estimated median duration of stay among survivors was 9.3 days (with 95% staying 0.8 to 32.9 days) and among non-survivors was 12.7 days (1.6 to 37.7 days). The censoring adjusted probability of ICU admission for male patients was 48.5% (95% confidence interval 41.8% to 56.3%) and for female patients was 32.0% (26.6% to 38.4%). For patients requiring critical care, the median duration of ICU stay was 10.6 days (with 95% staying 1.3 to 30.8 days). The censoring adjusted case fatality ratio was 23.5% (95% confidence interval 19.6% to 28.2%) among male inpatients and 14.9% (11.8% to 18.6%) among female inpatients; mortality risk increased with age for both male and female patients. Reductions in RE were identified over the study period within each region.ConclusionsAmong residents of California and Washington state enrolled in Kaiser Permanente healthcare plans who were admitted to hospital with covid-19, the probabilities of ICU admission, of long hospital stay, and of mortality were identified to be high. Incidence rates of new hospital admissions have stabilized or declined in conjunction with implementation of social distancing interventions.

Covid-19 related hospital admissions in the United States: needs and outcomes

“…For example, one New York cohort study initially reported a mortality of 88% for patients requiring mechanical ventilation before readers’ responses led to a correction clarifying that the rate was 25% and would grow to an uncertain extent because 72% of patients were still in hospital 4. In contrast, the two linked cohort studies from the United States provide rigorous outcome ascertainment and adjustment for case mix 67. By delaying publication until most enrolled patients had confirmed outcomes and by using modern survival analysis methods these authors have greatly enhanced our understanding of the epidemiology of covid-19.…”

“…Lewnard and colleagues (doi:10.1136/bmj.m1923) report on 1840 people with covid-19 at Kaiser Permanente system hospitals in California and Washington state 6. Median age was 61 years with 25% being 48 years or younger.…”

“…The studies also provide rigorous confirmation of risk factors for poor outcomes that had been suggested in early reports. While older age is the greatest risk factor for adverse outcomes, including death, the burden of severe covid-19 illness is clearly borne across the lifespan, as most hospital admissions (53%7 to 60%6) occurred in patients younger than 65 years. Early reports with incomplete follow-up are liable to considerable errors in reporting absolute event rates but often provide reasonable estimates of relative risks.…”

Covid-19 care before, during, and beyond the hospital

“…Independent risk factors for death included black and Asian ethnicity (versus white ethnicity) and deprivation, similar to findings from the United States 11. An integrated health delivery plan in California and Washington states has used data from 9.6 million enrollees in a study that reported 1277 hospital admissions and 15% mortality in hospital to examine community transmission dynamics 12…”

Efficacy and safety of tocilizumab in COVID-19 patients: A Meta-Analysis

“…patients from California and Washington. 48 Over 50% of patients were with a length of hospital stay of 20 days or more. 49 Immunomodulatory agents remain a promising strategy for the treatment of severe COVID-19, since it can attenuate the increased in ammatory response of the patients.…”