Association between different screening strategies for SARS-CoV-2 and
deaths and severe disease in Italy.
Abstract
Background The WHO recommends testing any suspected person with Severe
Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2), in order to limit
the spread of the epidemic. In Italy, some Regions opted for extensive
testing, whereas others limited tests to selected subjects. To assess
the influence of different strategies, we examined the incidence of
death and severe cases in Italy. Methods Data on new cases of
SARS-CoV-2, number of tests, deaths, and admissions to Intensive Care
Units (ICU) were retrieved in each Italian Region, from February 24th to
March 18th, 2020. As an index of different screening strategies, the
number of tests/positive test results (T/P) ratio as of March 7th, 2020,
was considered. The cumulative number of deaths and of new severe cases,
between March 23thand 25th was recorded. The association of those two
outcomes with the number of T/P ratio was assessed using linear
regression models. Results In the interval between March 23th-25th,
recorded deaths (*million inhabitants) were 14(3-54), whereas severe
cases were 31(10-112). Both the number of deaths and that of severe
cases showed a significant correlation (R2 .38 and .37, with
p<.01) with the T/P ratio. Deaths and severe cases were
associated with higher mean personal income and lower density of General
Practioners (GPs). The association of T/P with severe cases and deaths
retained statistical significance after adjusting for mean personal
income (R2 .20 and .21, respectively; both p=.04) and GPs density (R2.22
and .21, respectively; both p=.03). Conclusions A more aggressive
screening strategy for SARS-Cov-2, was associated with lower rates of
death and severe disease in Regions of Italy.