Association of COVID-19 case-fatality rate with disease burden: an ecological analysis in Italy during the first wave.

Timelli, Laura; Liuzzi, Giuseppina; Cannavacciuolo, Alessandro; Petrosillo, Nicola; Puro, Vincenzo; Girardi, Enrico

OBJECTIVES: : Case-fatality-rate (CFR) of COVID-19 during the first wave of pandemic showed significant geographic heterogeneity in Italy. By using an ecological approach, we aimed to explore possible association between CFR and measures of disease burden in Italian regions. METHODS: : We analyzed cumulated regional data for period February 24–May 11, 2020, to assess the association of CFR with cumulative incidence of COVID-19 and ratio between maximum number of COVID-19 patients in intensive care units (ICU) and ICU beds available before the pandemic (ICU load) adjusting for median age of patients at disease, number of nasopharyngeal swabs performed per confirmed case and prevalence chronic diseases. RESULTS: : During the study period, COVID-19 CFR in Italian regions ranged between 5.0% and 18.4%. In multivariable regression, CFR was significantly associated with cumulative incidence (relative rate [RR]=1.02 per 100 cases/1 million increase), median age (RR=1.07 per 1 year increase) and ICU load (RR=1.72, 2.18 and 2.57, for >40%-70% vs <=40%, 70%-140% and >=140 vs <=40%, respectively). CONCLUSIONS: : High burden of COVID-19 may contribute to increase fatality of the disease, possibly by increasing demand for care of critically ill patients beyond health system capability.