Characteristics and outcomes of clinically diagnosed RT-PCR swab negative COVID-19: a retrospective cohort study

Abstract

Patients with strong clinical features of COVID-19 with negative real time polymerase chain reaction (RT-PCR) SARS-CoV-2 testing are not currently included in official statistics. The scale, characteristics and clinical relevance of this group are not well described. We performed a retrospective cohort study in two large London hospitals to characterize the demographic, clinical, and hospitalization outcome characteristics of swab-negative clinical COVID-19 patients. We found 1 in 5 patients with a negative swab and clinical suspicion of COVID-19 received a clinical diagnosis of COVID-19 within clinical documentation, discharge summary or death certificate. We compared this group to a similar swab positive cohort and found similar demographic composition, symptomology and laboratory findings. Swab-negative clinical COVID-19 patients had better outcomes, with shorter length of hospital stay, reduced need for > 60% supplementary oxygen and reduced mortality. Patients with strong clinical features of COVID-19 that are swab-negative are a common clinical challenge. Health systems must recognize and plan for the management of swab-negative patients in their COVID-19 clinical management, infection control policies and epidemiological assessments.

Comparison of clinical characteristics and outcome in RT-PCR positive and false-negative RT-PCR for COVID-19: A Retrospective analysis

“…This report found RT-PCR positivity in 67.8% of the SARI patients. This result was similar to previous studies, which reported RT-PCR positivity ranges from 59.2% to 85.8% [10,11]. Di Paolo et al discussed the possibility of positive RT-PCR in repeat testing, which was 4% in their report [19].…”

“…RT-PCR negative patients had less oxygen requirement (number of days on oxygen) and a better in-hospital survival rate. Middleton et al described a 60% lower probability of death and duration of hospital stay in RT-PCR negative patients [10]. Interestingly, the median duration of illness till admission did not differ between RT-PCR positive and negative groups.…”

“…Some of the SARI cases may be attributed to pulmonary edema or other atypical viral infections on subsequent evaluation; however, many cases remain without alternate aetiology (false-negative RT-PCR), and the dilemma remains whether to treat them as RT-PCR positive. There are few reports which compared the COVID-19 patients based on RT-PCR results with conflicting observations [9][10][11][12][13]. Furthermore, studies on the Indian population are also lacking in this regard.…”

Serum ferritin as a predictive biomarker in COVID-19. A systematic review, meta-analysis and meta-regression analysis

“…The RT-PCR positive COVID-19 population is well defined. However, owing to low sensitivity of the diagnostic tests including RTPCR, false negativity [ 21 ] is an important problem and “clinically diagnosed RT-PCR negative COVID-19 is now increasingly being recognized [ 22 , 23 ]. In our study we used both RT-PCR positive COVID-19 and clinically diagnosed RT-PCR negative COVID-19 cases.…”

RT-PCR negative COVID-19

“…Secondly, the study was also not designed nor powered to describe the epidemiology or outcomes of RT-PCR negative COVID. Although we were not able to evaluate the prevalence of RT-PCR negative COVID-19 suspects in our patient population, their considerable prevalence has been suggested previously [ 27 ]. Thirdly, we had limited longitudinal serologic data to determine if some of the earlier seronegative Probables converted to seropositive.…”