JMIR Public Health Surveill. 2022 May 17. doi: 10.2196/37668. Online ahead of print.
BACKGROUND: Most studies of long covid (symptoms of COVID-19 beyond 4 weeks) have focused on people hospitalised in their initial illness. Long covid is thought to be under-recorded in UK primary care electronic records.
OBJECTIVE: We sought to determine which symptoms people present to primary care following COVID-19, and whether presentation differs in people who were not hospitalised, and post-long covid mortality.
METHODS: We used routine data from the nationally representative Primary Care Sentinel Cohort of the Oxford-Royal College of General Practitioners Research and Surveillance Centre (N=7.4million), applying a pre-defined long covid phenotype and grouped by whether the illness index was in hospital or community. We included COVID-19 cases between 1st-March-2020 and 1st-April-2021. We conducted a before and after analysis of pre-specified long covid symptoms identified by the Office of National Statistics, comparing symptoms presented between one and six months after their index infection matched with the same months one year previously. We conducted logistic regression analysis, quoting odds ratios with 95% confidence intervals, reporting differences between those with an index community infection compared to those who had been hospitalised, and separately associations with all-cause mortality.
RESULTS: 5.6% (416,505/7,396,702) and 1.8% (7,623/416,505) of patients respectively had a coded diagnosis of COVID-19 and diagnosis or referral for long covid. People coded as having long covid were significantly more likely to have presented the pre-specified symptoms after vs before COVID-19 infection (odds ratios 2.66 [2.46-2.88] for those with index community infection and 2.42 [2.03-2.89] for those hospitalised). Following an index community infection, patients were more likely to present with non-specific symptoms (odds ratio 3.44 [3.00-3.95], P<.001) than following a hospital admission (odds ratio 2.09 [1.56-2.80], P<.001). Mental health sequelae were more commonly associated with hospital admission index infections (odds ratio 2.21 [1.64-2.96]) compared to community (odds ratio 1.36 [1.21-1.53], P<.001). People presenting to primary care following hospital infection were more likely to be male (odds ratio 1.43 [1.25-1.64], P<.001), more socioeconomically deprived (odds ratio 1.42 [1.24-1.63], P<.001); and to have multi-morbidity (odds ratio 1.41 [1.26-1.57], P<.001) than those presenting after an index community infection. All-cause mortality in people with long covid was associated with increasing age; male gender (odds ratio 3.32 [1.34-9.24], P<.01) and higher multi-morbidity score (odds ratio 2.11 [1.34-3.29], P<.001). One or more vaccine doses was associated with reduced odds of mortality (odds ratio 0.10 [0.03-0.35], P<.001).
CONCLUSIONS: The low percentage of people recorded as having long covid following COVID-19 reflects either low prevalence or under-recording. The characteristics and comorbidities of those presenting with long covid following a community infection are different from those who were hospitalised with their index infection. This study provides insights into the presentation of long covid in primary care and implications for workload.
CLINICALTRIAL: Not applicable.