Patterns of repeated diagnostic testing for COVID-19 in relation to patient characteristics and outcomes

J Intern Med. 2021 May;289(5):726-737. doi: 10.1111/joim.13213. Epub 2020 Dec 19.

Abstract

Background: Whilst the COVID-19 diagnostic test has a high false-negative rate, not everyone initially negative is re-tested. Michigan Medicine, a primary regional centre, provided an ideal setting for studying testing patterns during the first wave of the pandemic.

Objectives: To identify the characteristics of patients who underwent repeated testing for COVID-19 and determine if repeated testing was associated with downstream outcomes amongst positive cases.

Methods: Characteristics, test results, and health outcomes for patients presenting for a COVID-19 diagnostic test were collected. We examined whether patient characteristics differed with repeated testing and estimated a false-negative rate for the test. We then studied repeated testing patterns in patients with severe COVID-19-related outcomes.

Results: Patient age, sex, body mass index, neighbourhood poverty levels, pre-existing type 2 diabetes, circulatory, kidney, and liver diseases, and cough, fever/chills, and pain symptoms 14 days prior to a first test were associated with repeated testing. Amongst patients with a positive result, age (OR: 1.17; 95% CI: (1.05, 1.34)) and pre-existing kidney diseases (OR: 2.26; 95% CI: (1.41, 3.68)) remained significant. Hospitalization (OR: 7.88; 95% CI: (5.15, 12.26)) and ICU-level care (OR: 6.93; 95% CI: (4.44, 10.92)) were associated with repeated testing. The estimated false-negative rate was 23.8% (95% CI: (19.5%, 28.5%)).

Conclusions: Whilst most patients were tested once and received a negative result, a meaningful subset underwent multiple rounds of testing. These results shed light on testing patterns and have important implications for understanding the variation of repeated testing results within and between patients.

Keywords: COVID-19; diagnostic testing; false-negative rate.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Age Factors
  • COVID-19 Nucleic Acid Testing* / methods
  • COVID-19 Nucleic Acid Testing* / standards
  • COVID-19 Nucleic Acid Testing* / statistics & numerical data
  • COVID-19* / diagnosis
  • COVID-19* / epidemiology
  • COVID-19* / physiopathology
  • COVID-19* / therapy
  • Comorbidity
  • Diagnostic Errors / prevention & control
  • False Negative Reactions*
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Intensive Care Units / statistics & numerical data*
  • Kidney Diseases / epidemiology
  • Male
  • Michigan / epidemiology
  • Middle Aged
  • Public Reporting of Healthcare Data
  • SARS-CoV-2 / isolation & purification*
  • Severity of Illness Index
  • Socioeconomic Factors