Self-Reported Symptoms of SARS-CoV-2 Infection in a Nonhospitalized Population in Italy: Cross-Sectional Study of the EPICOVID19 Web-Based Survey

• DOI: 10.2196/21866
• Publication Date: 2020-07-10T12:14:45Z
• Authors: Fulvio Adorni; Federica Prinelli; Fabrizio Bianchi; Andrea Giacomelli; Gabriele Pagani; Dario Bernacchia; Stefano Rusconi; Stefania Maggi; Caterina Trevisan; Marianna Noale; Sabrina Molinaro; Luca Bastiani; Loredana Fortunato; Nithiya Jesuthasan; Aleksandra Sojic; Carla Pettenati; Marcello Tavio; Massimo Andreoni; Claudio Mastroianni; Raffaele Antonell...; Massimo Galli
• Keywords: Adult; Male; cross-sectional; Adolescent; Health Status; Pneumonia, Viral; Settore MED/17 - MALATTIE INFETTIVE; Betacoronavirus; 03 medical and health sciences; 0302 clinical medicine; Odds Ratio; voluntary respondents; Humans; Pandemics; Aged; Aged, 80 and over; Original Paper; web-based survey; SARS-CoV-2; COVID-19; COVID-19, Web-based survey, Voluntary respondents, Self-reported symptom, SARS-CoV-2, Nasopharyngeal swab testing, Cross-sectional; Middle Aged; Health Surveys; COVID-19; SARS-CoV-2; cross-sectional; nasopharyngeal swab testing; self-reported symptom; voluntary respondents; web-based survey; Adolescent; Adult; Aged; Aged, 80 and over; Area Under Curve; Betacoronavirus; COVID-19; Coronavirus; Coronavirus Infections; Cross-Sectional Studies; Female; Health Surveys; Humans; Italy; Male; Middle Aged; Odds Ratio; Pandemics; Pneumonia, Viral; Population Surveillance; Prevalence; ROC Curve; SARS-CoV-2; Self Report; Severe Acute Respiratory Syndrome; Young Adult; Health Status; 3. Good health; Coronavirus; Cross-Sectional Studies; Italy; Area Under Curve; self-reported symptom; Female; Public aspects of medicine; RA1-1270; Coronavirus Infections; nasopharyngeal swab testing

Background Understanding the occurrence of symptoms resembling those of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a large nonhospitalized population at the peak of the epidemic in Italy is of paramount importance; however, data are currently scarce.

Objective The aims of this study were to evaluate the association of self-reported symptoms with SARS-CoV-2 nasopharyngeal swab (NPS) test results in nonhospitalized individuals and to estimate the occurrence of symptoms associated with coronavirus disease (COVID-19) in a larger nontested population.

Methods EPICOVID19 is a self-administered cross-sectional voluntary web-based survey of adults throughout Italy who completed an anonymous questionnaire in the period of April 13 to 21, 2020. The associations between symptoms potentially related to SARS-CoV-2 infection and NPS results were calculated as adjusted odds ratios (aORs) with 95% CIs by multiple logistic regression analysis controlling for age, sex, education, smoking habits, and number of comorbidities. Thereafter, for each symptom and for combinations of the symptoms, we calculated the sensitivity, specificity, accuracy, and areas under the curve (AUCs) in a receiver operating characteristic (ROC) analysis to estimate the occurrence of COVID-19–like infection in the nontested population.

Results A total of 171,310 people responded to the survey, of whom 102,543 (59.9%) were women; mean age 47.4 years. Out of the 4785 respondents with known NPS test results, 4392 were not hospitalized. Among the 4392 nonhospitalized respondents, those with positive NPS tests (856, 19.5%) most frequently reported myalgia (527, 61.6%), olfactory and taste disorders (507, 59.2%), cough (466, 54.4%), and fever (444, 51.9%), whereas 7.7% were asymptomatic. Multiple regression analysis showed that olfactory and taste disorders (aOR 10.3, 95% CI 8.4-12.7), fever (aOR 2.5, 95% CI 2.0-3.1), myalgia (aOR 1.5, 95% CI 1.2-1.8), and cough (aOR 1.3, 95% CI 1.0-1.6) were associated with NPS positivity. Having two to four of these symptoms increased the aOR from 7.4 (95% CI 5.6-9.7) to 35.5 (95% CI 24.6-52.2). The combination of the four symptoms showed an AUC of 0.810 (95% CI 0.795-0.825) in classifying positive NPS test results and then was applied to the nonhospitalized and nontested sample (n=165,782). We found that 7739 to 20,103 of these 165,782 respondents (4.4% to 12.1%) had experienced symptoms suggestive of COVID-19 infection.

Conclusions Our results suggest that self-reported symptoms are reliable indicators of SARS-CoV-2 infection in a pandemic context. A nonnegligible number of symptomatic respondents (up to 12.1%) were undiagnosed and potentially contributed to the spread of the infection.

Trial Registration ClinicalTrials.gov NCT04471701; https://clinicaltrials.gov/ct2/show/NCT04471701