SARS-CoV-2 lethality did not change over time in two Italian Provinces

Abstract

AbstractBackgroundSome experts recently reported that SARS-CoV-2 lethality decreased considerably, but no evidence is yet available. This retrospective cohort study aimed to evaluate whether SARS-CoV-2 case-fatality rate decreased with time, adjusting for several potential confounders.MethodsWe included all subjects diagnosed with SARS-CoV-2 infection in Ferrara and Pescara provinces, Italy. Information were collected from local registries, clinical charts, and electronic health records. We compared the case-fatality rate (after ≥28 days of follow-up) of the subjects diagnosed during April and March, 2020. We used Cox proportional hazards analysis and random-effect logistic regression, adjusting for age, gender, hypertension, type II diabetes, major cardiovascular diseases (CVD), chronic obstructive pulmonary diseases (COPD), cancer and renal disease.ResultsThe sample included 2493 subjects (mean age 58.6y; 47.7% males). 258 persons deceased, after a mean of 16.1 days of follow-up. The mean age of those who died substantially increased from March (78.1±11.0y) to April (84.3±10.2y). From March to April, the case-fatality rate did not decrease in the total sample (9.5% versus 12.1%; adjusted hazard ratio 0.93; 95% Confidence Interval: 0.71-1.21; p=0.6), and in any age-class.ConclusionsIn this sample, SARS-CoV-2 case-fatality rate did not decrease over time, in contrast with recent claims of a substantial improvement of SARS-CoV-2 clinical management. The findings require confirmation from larger datasets.Author summaryWhy was this study done?Some experts recently reported that SARS-CoV-2 lethality decreased considerably, but no evidence is yet available.What did the researchers do and find?We carried out a retrospective cohort study on 2493 SARS-CoV-2 infected subjects from two Italian provinces, evaluating the potential variation of the case-fatality rate over time.From March to April, SARS-CoV-2 case-fatality rate did not decrease, overall and in any age-class.What do these findings mean?The therapies and clinical management of SARS-CoV-2 infected subjects did not determine a substantial change of the clinical course of the disease from March to April, 2020.