Predictive values of symptoms for SARS-CoV-2 infection among primary care patients in Piedmont.

Objectives: to investigate the combinations of clinical features and symptoms that best predict the positive outcome of the SARS-CoV-2 swab in a primary care setting.

Design: prospective cohort study.

Setting And Participants: patients listed in the rosters of general practitioners volunteering for the study who reported flu-like symptoms and/or anosmia/ageusia between 01.03.2020 and 30.06.2020.

Main Outcome Measures: positive molecular swab result. The predictive value of the reported symptoms and their association with this outcome were estimated using multivariable logistic regression models, adopting an inverse probability weighting approach.

Results: a swab was requested for 1,045 (77.2%) out of 1,354 patients included in the study: 79.6% of them were tested, with a positive result in 50.4% of cases. Patients aged 40 to 64 years (OR 1.59; 95%CI 1.09-2.33) and those older than 64 years (OR 2.64; 95%CI 1.66-4.19) showed a higher likelihood of a positive swab results, compared with younger subjects (<40 years). A positive association with a positive swab result was observed among patients reporting fever >37.5°C (OR 1.67; 95%CI: 1.18-2.36) and anosmia/ageusia (OR 1.44; 95%CI: 1.01-2.04). The predictive value of fever tended to increase with increasing age, while an opposite trend was observed for anosmia/ageusia. No difference by gender was observed.

Conclusions: among patients reporting flu-like symptoms in a general practice setting, fever >37.5 and anosmia/ageusia were predictive of a positive SARS-CoV-2 swab test result and this association was modified by age. Although the generalizability of these findings might be limited, this study highlights the importance of the contribution of the research conducted in primary care settings to the definition of effective and sustainable strategies to contrast the pandemic emergency.