COVID-Q: Validation of the first COVID-19 questionnaire based on patient-rated symptom gravity

Objectives: The aim of the present study was to develop and validate the CoronaVirus-Disease-2019 (COVID-19) Questionnaire (COVID-Q), a novel symptom questionnaire specific for COVID-19 patients, to provide a comprehensive evaluation that may be helpful for physicians, and evaluate the questionnaire's performance in identifying subjects at higher risk of testing positive. Materials and methods: Consecutive non-hospitalised adults who underwent nasopharyngeal-throat swab for severe-acute-respiratory-syndrome-coronavirus-2 (SARS-CoV-2) detection at Treviso Hospital in March 2020, were enrolled. Subjects were divided into positive (cases) and negative (controls). All subjects answered the COVID-Q. Patients not able to answer COVID-Q because of clinical conditions were excluded. Parallel Analysis and Principal Component Analysis identified items measuring the same dimension. The Item Response Theory (IRT)-based analyses evaluated the functioning of item categories, the presence of clusters of local dependence among items, item fit within the model and model fit to the data. Results: Answers obtained from 230 cases (113 males; mean age 55 years, range 20-99) and 230 controls (61 males; mean age 46 years, range 21-89) were analysed. Six components were extracted with parallel analysis: asthenia, influenza-like symptoms, ear and nose symptoms, breathing issues, throat symptoms, and anosmia/ageusia. The final IRT models retained 27 items as significant for symptom assessment. The total questionnaire's score was significantly associated with positivity to the molecular test: subjects with multiple symptoms were more likely to be affected (P <.001). Older age, male gender presence of breathing issues and anosmia/ageusia were significantly related to positivity (P <.001). Comorbidities had not a significant association with the COVID-19 diagnosis. Conclusion: COVID-Q could be validated since the evaluated aspects were overall significantly related to infection. The application of the questionnaire to clinical practice may help to identify subjects who are likely to be affected by COVID-19 and address them to a nasopharyngeal swab in order to achieve an early diagnosis.