Frequency of nasopharyngeal swab collection and positivity for SARS-CoV-2 infection in the population of the Italian province of Udine with and without chronic conditions.

ABSTRACT

Severity of SARS-CoV-2 infection is associated with comorbidities. However, no information is available on the frequency of nasopharyngeal swab collection and positivity depending on comorbidities. Using a cross-sectional design, we assessed the prevalence of SARS-CoV-2 tests and of positivity in the general population of the 530,000-inhabitant Italian province of Udine and in subgroups affected by chronic conditions in the first weeks of SARS-CoV-2 epidemic. Anonymous health databases were used as source of information to identify persons with 14 chronic conditions. From laboratory records we assessed the likelihood of real-time reverse-transcriptase polymerase chain reaction for SARS-CoV-2 and the frequency of positivity from February 29 to April 19, 2020, i.e., 7 weeks from the first case detected in the study area. Sex and age-stratified proportions were calculated in comorbidity subgroups. Multivariate regression was used to adjust for confounders. In the province, 236,623 persons had ≥1 chronic condition; 869 had positive tests. Persons with comorbidities were tested more than the others. However, most chronic conditions were not significantly associated with the prevalence of positivity, except psychiatric and neurological diseases and diabetes. In conclusion, despite more frequent testing, patients with most chronic diseases where equally likely to be diagnosed with SARS-CoV-2 as the general population. Chronic patients should adhere to general recommendations for preventing SARS-CoV-2 infection, but ad hoc restrictions do not seem necessary.