Risk factors associated with PCR repositivity in patients with COVID-19
after recovery in Guangzhou, China: a retrospective cohort study
Abstract
Some patients retested positive for SARS-CoV-2 following negative
testing results and discharge. However, the potential risk factors
associated with redetectable positive test results in a large sample of
patients who recovered from COVID-19 have not been well estimated. A
total of 745 discharged COVID-19 patients were enrolled between January
30, 2020, and September 9, 2020, in Guangzhou, China. Data on the
clinical characteristics, comorbidities, drug therapy, RT-PCR testing,
and contact modes to close contacts were collected. Patients who tested
positive for SARS-CoV-2 after discharge (positive retest patients) were
confirmed by guidelines issued by China. The repositive rate in
different settings was calculated. Among 745 discharged patients, 157
(21.1%; 95% CI, 18.2% to 24.0%) retested positive, of which 55
(35.0%) were asymptomatic, 15 (9.6%) had mild symptoms, 83 (52.9%)
had moderate symptoms and 4 (2.6%) had severe symptoms at the first
admission. The median time from discharge to repositivity was 8.0 days
(IQR, 8.0 to 14.0 days). Most positive retest patients were without
clinical symptoms, and lymphocyte cell counts were higher than before
being discharged. The likelihood of repositive testing for SARS-CoV-2
RNA was significantly higher among patients who were younger age (OR,
3.88; 95% CI, 1.74 to 8.66, 0 to 17 years old), had asymptomatic
severity (OR, 4.36; 95% CI, 1.47 to 12.95) and did not have clinical
symptoms (OR, 1.89; 95% CI, 1.32 to 2.70, without fever). We found that
the positive retest rate of COVID-19 was relatively high, and these
patients tested positive again with a median of 8.0 to 14.0 days after
discharge. Positive retest results were mainly observed in young
patients without severe clinical symptoms. These findings suggest that a
significant proportion of patients could carry viral fragments for a
long time, and effective management, such as a prolonged quarantine
phase for discharged patients, is necessary.