RESUMEN
INTRODUCTION: The aim of this study was to investigate how long hospitalized patients stayed positive to the nasopharyngeal swab, and what demographic and clinical factors influence the time-to-negative swab. METHODS: We enrolled in a multicenter, observational, retrospective study involving 17 COVID-19 units in eight cities of the Campania, southern Italy all patients hospitalized from March 2020 to May 2021 diagnosed with Severe Acute Respiratory Distress Syndrome-Coronavirus-2 (SARS-CoV-2) infection for whom time-to-negative swab was available. RESULTS: 963 patients were enrolled. We defined three groups considering time-to-negative swab: the first including patients with time-to-negative swab before the 26th day, the second including patients with time-to-negative swab from day 26 to day 39, and the third including patients with time-to-negative swab > 39 days. 721 (74.9%) patients belonged to the first group, 194 (20.1%) to the second, and 52 (5.4%) belonged to the third group. Belonging to group 2 and 3 seemed to be influenced by age (p value < 0.001), Charlson comorbidity index (p = 0.009), arterial hypertension (p = 0.02), cardiovascular disease (p = 0.017), or chronic kidney disease (CKD) (p = 0.001). The multivariable analysis confers a leading role to CKD, with an odds ratio of 2.3 as factor influencing belonging to the groups showing a longer time-to-negative swab. Patients with CKD and diabetes were more frequently in the third group. DISCUSSION: Our analysis showed that CKD is a factor related to longer time-to-negative swab, probably because of immunosuppression related to this condition.