The Predisposing Factors to Having a Coded Diagnosis of Long COVID

Background: Long COVID, which characterized by a constellation of persistent symptoms following the initial COVID-19 viral infection. Our primary questions were how the characteristics of people diagnosed with Long COVID differed from matched individuals who did not have a diagnosis of Long COVID after at least one confirmed positive COVID-19 test and how the diagnosis of Long COVID was influenced by COVID-19 vaccination. Methods: This was a retrospective observational cohort study using data collected from 1st January 2020 to 31st January 2024. The primary outcome was a primary care coded diagnosis, or referral for treatment, of Long COVID following an acute COVID-19 infection. Findings: We identified 26626 individuals with a diagnosis of Long COVID and at least one previous recorded COVID-19 positive test. These were matched by age and sex with 133165 individuals with at least one previous recorded COVID-19 positive test but no recorded diagnosis of Long COVID. There was a higher proportion of people with 2,3 4 and 5 or more comorbidities in the diagnosed Long COVID group. Black and Black British ethnicity (+28%) and Mixed ethnicity (+37%) vs White ethnicity were associated with a higher likelihood of a Long COVID diagnosis. Those in the most disadvantaged Townsend Index quintile were more than 2.3 times as likely to have Long COVID than the most advantaged quintile. Risk of Long COVID increased by 5.7% per comorbidity. Risk of Long COVID doubled for every additional positive COVID test.There also a higher proportion of people with more than one COVID-19 positive test and more than one COVID-19 vaccination in the diagnosed Long COVID group.Finally, we went on to look at mortality following a COVID-19 infection. It was apparent that a diagnosis of Long COVID was associated with a reduced mortality rate. Each COVID vaccine reduced chance of death by 42%. Female sex was associated with lower risk of death. More disadvantaged individuals by Townsend quintile were more likely to have died  - nearly 2x for most deprived compared to least deprived quintile.  Each additional comorbidity increases chance of death by 44%. Each positive COVID-19  test increased chance of death by 5%. Interpretation: Increasing social disadvantage was associated with a greater likelihood of being diagnosed with Long COVID as was being of Black/Mixed ethnicity. Risk of Long COVID increased by 5.7% per comorbidity. Risk of Long COVID doubled for every additional positive COVID test with vaccination number modulating this effect. Diagnosis of Long COVID was associated with a reduced mortality over a 4 year period. Funding: The time of co-author RW was supported by the NIHR Applied Research Collaboration Greater Manchester (NIHR200174) and the NIHR Manchester Biomedical Research Centre (NIHR203308). Declaration of Interest: No author has any conflict of interest. Ethical Approval: The legal basis for use of patient data in this study was defined in the national Control of Patient Information (COPI) notice (Notice under Regulation 3(4) of the Health Service Control of Patient Information Regulations of 2002) which gives NHS organisations a legal requirement to share data for the purposes of the COVID-19 response. The study was also reviewed and approved by the Greater Manchester Care Record (GMCR) Expert Research Group (ERG) reference number RQ066. The data used in the analyses presented were obtained with the permission of the Greater Manchester Care Record Board and were fully anonymised prior to being made available to the investigators.