Symptom- and Prevention-Based Testing of COVID-19 in Nursing Home Residents: A Retrospective Cohort Study.

Nursing homes (NH) residents with COVID-19 can either be tested because of presence of core symptoms (S-based) or because of transmission prevention (TP-based). The investigated study sample included all NH residents who underwent SARS-CoV-2 RT-PCR testing between March 16, 2020 and May 31, 2020 (n = 380). Clinical symptoms, temperature, and oxygen saturation were extracted from medical records, 7 days before to 14 days after testing. COVID-19 was confirmed in 81 (21%) residents; 36 (44%) S-based and 45 (56%) TP-based: 45. Cycle threshold (CT) values did not differ between the groups. In the 7 days prior to the test falling (32%), somnolence (25%) and fatigue (21%) occurred in both groups. Two days before the test, we observed a stronger decrease in oxygen saturation and an increase in temperature for the S-based group compared to the T-based group that remained up to 10 days after testing. Residents within the S-based group were 2.5 times more likely to increased mortality within 30 days than residents in the TP-based group (HR, 2.56; 95% 1.3-5.2). Although, 73% of the T-based group did eventually develop core symptoms. Thus, attention to falling and daily measures of temperature and oxygen saturation can contribute to earlier detection.