Factors associated with delayed diagnosis of symptomatic adult COVID-19 cases presenting to primary care: a population-wide study during transition from Delta to Omicron BA.1 in Singapore

Ren Ying Tan; Betty Wong; Ruth Lim; Ching Li Lee; Joyce Tan; Kelvin Bryan Tan; Liang En Wee

doi:10.1016/j.lanwpc.2023.100919

Factors associated with delayed diagnosis of symptomatic adult COVID-19 cases presenting to primary care: a population-wide study during transition from Delta to Omicron BA.1 in Singapore

Lancet Reg Health West Pac. 2023 Sep 27:41:100919. doi: 10.1016/j.lanwpc.2023.100919. eCollection 2023 Dec.

Authors

Ren Ying Tan¹, Betty Wong¹, Ruth Lim¹, Ching Li Lee¹, Joyce Tan¹, Kelvin Bryan Tan^{1

2}, Liang En Wee^{3

4

5}

Affiliations

¹ Ministry of Health, Singapore.
² Saw Swee Hock School of Public Health, National University of Singapore, Singapore.
³ National Centre for Infectious Diseases, Singapore.
⁴ Duke-NUS Graduate Medical School, National University of Singapore, Singapore.
⁵ Department of Infectious Diseases, Singapore General Hospital, Singapore.

Abstract

Background: During pandemics, avoiding time delay in diagnosing infection is crucial. We evaluated factors associated with delayed diagnosis of symptomatic SARS-CoV-2 infection in a national cohort of adult Singaporeans, during which emergence of the more transmissible Omicron variant shifted pandemic management towards endemicity.

Methods: Retrospective cross-sectional study amongst all adult Singaporeans diagnosed with symptomatic SARS-CoV-2 infection during the transition from Delta to Omicron BA.1 (September 2021-February 2022). SARS-CoV-2 testing was fully subsidised and compulsory for all symptomatic individuals presenting at primary care. Results and demographic information were extracted from national databases. Time to diagnosis was defined as days from symptom-onset to diagnosis (date of first positive SARS-CoV-2 test); dichotomising into no delay (≤24 h from symptom-onset) and delay >24 h. Multivariable logistic regression was utilised to assess factors associated with delay >24 h, and association of delay >24 h with progression to severe COVID-19.

Findings: Of 149,063 Singaporean adults presenting with symptomatic SARS-CoV-2 infection, 75.9% (113,195/149,063) were diagnosed within 24 h of symptom-onset. On multivariable analysis, female gender, older age (>60 years), Chinese (vs. Malay) ethnicity, socioeconomic status (housing type), primary care characteristics, presentation during Omicron BA.1 (vs. Delta), symptom-onset on Friday/Saturday (vs. Monday), and not having completed a primary vaccination series were independently associated with higher odds of delay >24 h. Delay >24 h was independently associated with severe COVID-19 (adjusted odds-ratio, aOR = 1.45, 95% CI = 1.27-1.65, p < 0.001).

Interpretation: At-risk populations (unvaccinated, age >60 years) had higher odds of delay in diagnosis. Delay >24 h in diagnosis was independently associated with severe COVID-19.

Funding: This study was not grant-funded.

Keywords: COVID-19; Delay; Diagnosis; Primary care; SARS-CoV-2.