[Evaluation of the diagnostic test for rapid detection of covid-19 antigen (Panbio Covid rapid test) in primary care]. / Evaluación de la prueba diagnóstica de detección rápida de antígeno de covid-19 (Panbio Covid rapid test) en atención primaria.

OBJECTIVE: COVID-19 infection requires early diagnosis, with PCR being the gold standard test. The protocols advocate the use of rapid antigenic tests that require evaluation in actual clinical practice. The objective was to evaluate the diagnostic test for rapid antigen detection, Panbio Covid rapid test, compared with PCR, in patients with symptoms of 5 or less days of evolution and with a high-suspicion of infection by COVID-19 in a health center. MATERIALS AND METHODS: 103 patients over 14 years of age who attended an urban health center located in the Usera District of Madrid, with high-suspicion of COVID-19 infection, in the first 5 days of evolution from the onset of symptoms during the month of November 2020. INTERVENTIONS: diagnostic tests for COVID-19 are performed: antigen and PCR. RESULTS: The prevalence of the disease was 24.3% according to the PCR test and 17.5% according to the rapid antigenic test. The sensitivity was 72% (95% CI: 54.3-89.6%). The specificity was 100%. The positive and negative predictive values were 100% and 91.8% respectively. In the bivariate analysis, there was no relationship between symptoms and the presence of disease, except for myalgias (p=0.030). The multivariate analysis found a relationship between cough, dyspnea, fever, myalgia, anosmia/ageusia, and ocular symptoms and the presence of disease. CONCLUSIONS: The sensitivity and specificity for the Panbio rapid antigen test are similar to other studies performed in primary care. In high-prevalence of disease and with highly suspected symptoms, positive test results can be considered definitive, but negative results will require confirmation. Myalgia, fever, dyspnea, anosmia/ageusia, and ocular symptoms may be more related to the presence of COVID-19.

Utility of preoperative polymerase chain reaction testing during SARS-CoV-2 pandemic: The challenge of evolving incidence.

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27 × 10e-4 (according to official data of new cases diagnosed by PCR) to 4.69 × 10e-4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.

Utility of preoperative polymerase chain reaction testing during SARS-CoV-2 pandemic: The challenge of evolving incidence. / Utilidad de la prueba de reacción en cadena de la polimerasa preoperatoria durante la pandemia por SARS-CoV-2: el desafío de la incidencia cambiante.

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27*10e -4 (according to official data of new cases diagnosed by PCR) to 4.69*10e -4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.