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Observational Study
. 2021 Oct 1;11(10):e051707.
doi: 10.1136/bmjopen-2021-051707.

Factors associated with COVID-19 viral and antibody test positivity and assessment of test concordance: a retrospective cohort study using electronic health records from the USA

Lisa Lindsay  1 , Matthew H Secrest  2 , Shemra Rizzo  2 , Daniel S Keebler  2 , Fei Yang  3 , Larry Tsai  4
Affiliations
Observational Study

Factors associated with COVID-19 viral and antibody test positivity and assessment of test concordance: a retrospective cohort study using electronic health records from the USA

Lisa Lindsay et al. BMJ Open. .

Abstract

Objectives: To identify factors associated with COVID-19 test positivity and assess viral and antibody test concordance.

Design: Observational retrospective cohort study.

Setting: Optum de-identified electronic health records including over 700 hospitals and 7000 clinics in the USA.

Participants: There were 891 754 patients who had a COVID-19 test identified in their electronic health record between 20 February 2020 and 10 July 2020.

Primary and secondary outcome measures: Per cent of viral and antibody tests positive for COVID-19 ('positivity rate'); adjusted ORs for factors associated with COVID-19 viral and antibody test positivity; and per cent concordance between positive viral and subsequent antibody test results.

Results: Overall positivity rate was 9% (70 472 of 771 278) and 12% (11 094 of 91 741) for viral and antibody tests, respectively. Positivity rate was inversely associated with the number of individuals tested and decreased over time across regions and race/ethnicities. Antibody test concordance among patients with an initial positive viral test was 91% (71%-95% depending on time between tests). Among tests separated by at least 2 weeks, discordant results occurred in 7% of patients and 9% of immunocompromised patients. Factors associated with increased odds of viral and antibody positivity in multivariable models included: male sex, Hispanic or non-Hispanic black or Asian race/ethnicity, uninsured or Medicaid insurance and Northeast residence. We identified a negative dose effect between the number of comorbidities and viral and antibody test positivity. Paediatric patients had reduced odds (OR=0.60, 95% CI 0.57 to 0.64) of a positive viral test but increased odds (OR=1.90, 95% CI 1.62 to 2.23) of a positive antibody test compared with those aged 18-34 years old.

Conclusions: This study identified sociodemographic and clinical factors associated with COVID-19 test positivity and provided real-world evidence demonstrating high antibody test concordance among viral-positive patients.

Keywords: COVID-19; epidemiology; infectious diseases; molecular diagnostics; public health.

PubMed Disclaimer

Conflict of interest statement

Competing interests: LL, MHS, SR, DSK and LT are employed by and hold shares in Genentech. FY is employed by and holds shares in Roche Diagnostics.

Figures

Figure 1
Figure 1
Flow diagram of study population.
Figure 2
Figure 2
SARS-CoV-2 viral test positivity and days since COVID-like illness by setting. C2, cohort 2.
Figure 3
Figure 3
Frequency and co-occurrence of common conditions in patients positive for SARS-CoV-2 via viral test.
Figure 4
Figure 4
Density of agreement among patients who received an initial viral positive test and subsequent antibody positive test by weeks between tests and immunocompromised status.
Figure 5
Figure 5
ORs and 95% CIs of SARS-CoV-2-positive viral test obtained via multivariable logistic regression. BMI, body mass index; GERD, gastroesophageal reflux disease.
Figure 6
Figure 6
ORs and 95% CIs of COVID-19-positive antibody test obtained via multivariable logistic regression. BMI, body mass index.
Figure 7
Figure 7
Number of patients tested and per cent positive for initial SARS-CoV-2 viral test by age.
See this image and copyright information in PMC

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