www.medrxiv.org/content/10.1101/2020.10.19.20214494v1.full-text
Reports of “Long-COVID”, are rising but little is known about prevalence, risk factors, or whether it is possible to predict a protracted course early in the disease. We analysed data from 4182 incident cases of COVID-19 who logged their symptoms prospectively in the COVID Symptom Study app. 558 (13.3%) had symptoms lasting >28 days, 189 (4.5%) for >8 weeks and 95 (2.3%) for >12 weeks. Long-COVID was characterised by symptoms of fatigue, headache, dyspnoea and anosmia and was more likely with increasing age, BMI and female sex. Experiencing more than five symptoms during the first week of illness was associated with Long-COVID, OR=3.53 [2.76;4.50]. A simple model to distinguish between short and long-COVID at 7 days, which gained a ROC-AUC of 76%, was replicated in an independent sample of 2472 antibody positive individuals. This model could be used to identify individuals for clinical trials to reduce long-term symptoms and target education and rehabilitation services.
Of the 4182 COVID-19 swab positive users, 558 (13.3%) met the LC28 definition with a median duration of 41 days (IQR[33,63] of whom 189 (4.5%) met LC-56, and 95 (2.3%) LC94. In contrast 1591 (38.0%) had short disease duration (median 6, IQR[4-8]). The proportion with LC28 were comparable in all three separate countries (GB 13.3%, USA 16.1%, Sweden 12.1% p=0.35) and for LC56 (GB 4.7%, USA 5.5%, Sweden 2.5% p=0.07).
Table 1summarises the descriptive characteristics of the study population overall and stratifying by symptom/disease duration. Age was significantly associated with Long-COVID (LC28) rising from 9.9% in 18-49 year olds to 21.9% in those aged >=70 (p < 0.0005), with a clear escalation in OR by age decile (Figure 1b), although females aged 50-60 had the highest odds. (ST2). Individuals with Long-COVID were more likely to have required hospital assessment in the acute period. LC28 disproportionately affected women (14.9%) compared to men (9.5%), although this sex effect was not significant in the older age-group. Long-COVID affected all socio-economic groups (assessed using Index of Multiple Deprivation), (Supplementary Figure 2). Asthma was the only/unique pre-existing condition providing significant association with long-COVID-19 (OR = 2.14 [1.55-2.96]).