Methods
We retrieved daily data on new cases of SARS-CoV-2 (i.e., individuals
with positive test results), number of tests (reverse transcription
polymerase chain reaction; RT-PCR) performed, deaths, and admissions to
Intensive Care Units (ICU) in each Region, from February
24th to March 18th, 2020, obtained
from the Health Ministry website2. Demographic,
socioeconomic and healthcare organization data were retrieved from the
National Institute of Statistics (ISTAT)3.
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 subsequent evolution of
the epidemic was assessed through the cumulative number of deaths and of
new severe cases, between March 23th and
25th, inclusive; the latter were defined as a
composite of death and admission to ICU. This work is based on publicly
available data, needing no ethical approval.
The association of those two outcomes with the number of T/Pratio at
March 7th was assessed using a linear regression model. For each
confounder significantly associated with outcomes, multivariate linear
regression models were applied to assess the independent contribution of
T/P, assuming two-sided p<.05 as significant. Analyses were
performed on SPSS (SPSS-Inc., Chicago, IL, USA) 25.0.