Prevalence and risk factors for long COVID after mild disease: a longitudinal study with a symptomatic control group

Abstract

BackgroundThere is limited data on the prevalence and risk factors for long COVID, with a shortage of prospective studies with appropriate control groups and adequate sample size. We therefore performed a prospective study to determine the prevalence and risk factors for long COVID. MethodsWe recruited patients age ≥ 15 years who were clinically suspected of having acute SARS-CoV-2 infection from September 2020 to April 2021. Nasopharyngeal swabs were collected for RT-PCR 3-5 days post symptom onset. Clinical and sociodemographic characteristics were collected using structured questionnaires from persons positive and negative for SARS-COV-2. Follow-up was performed by telephone interview to assess early outcomes and persistent symptoms. For COVID-19 cases, 5D-3L EuroQol questionnaire was used to assess the impact of symptoms on quality of life.ResultsWe followed 814 participants (412 COVD-19 positive and 402 COVID-19 negative persons) of whom the majority (741 / 814) had mild symptoms. Both the COVID-19 positive and the COVID-19 negative groups had similar sociodemographic and clinical characteristics, except for the rate of hospitalization (15.8% vs 1.5%, respectively). One month after disease onset, 122 (29.6%) individuals reported residual symptoms in the COVID-19 positive group or the long COVID group versus 24 (6%) individuals in the COVID-19 negative group. In the long COVID group, fatigue, olfactory disorder, and myalgia were the most frequent symptoms which occurred in the acute phase. Compared to recovered patients, female sex, older age and having > 5 symptoms during the acute phase were risk factors for long COVID. Quality of life was evaluated in 102 out of 122 cases of long COVID with 57 (55.9%) reporting an impact in at least one dimension of the EuroQol 5D-3L questionnaire.ConclusionIn this prospective study consisting predominantly of patients with mild disease, the persistence of symptoms after acute disease was highly associated with long COVID-19 (29.6% vs 6% of COVID negative group). The risk factors for long COVID were older age, female sex, and polysymptomatic acute disease.

Comparison of methods to identify and characterize Post-COVID syndrome using electronic health records and questionnaires

“…Another important factor in uencing the variety among prevalence rates reported is whether a control group and comparisons on individual level with pre-COVID situation regarding symptoms and comorbidities has been included [15]. The few studies that have also included this crucial correction for a control group, like our study, generally report lower prevalence rates, similar to our results [6], [20]. Other obvious but central differences between studies on prevalence rates are whether PCS is de ned based on self-report and whether patients are included based on only one symptom or on multiple symptoms.…”

Thematic analysis to explore patients’ experiences with long COVID-19: a conceptual model of symptoms and impacts on daily lives

“…1 5 However, risk factors for long COVID-19 have been reported to include female sex, older age and a history of more than five symptoms during the infection. 11 12 Specific features of long COVID-19 have been identified via immune profiling, and include elevated humoral responses against SARS-CoV-2, and decreased levels of cortisol. 13 The reported prevalence of long COVID-19 ranges considerably, from 8% to 57% depending on the source and patient population evaluated.…”

The aftermath of Post COVID-19 Condition in Italy and the United States: an ecological comparison

“…Interestingly, nonmodifiable risk factors are unlikely to determine differences between the two nations, as both older age and female-male ratio are similar in both countries [34]. Of note, while severity of COVID-19 course puts at higher risk for more severe PCC, even mild cases are at risk for PCC [35,36], supporting the necessity for mitigation practices (e.g., mask wearing, physical distancing), since vaccines showed heterogeneous effects on lowering transmission rates of different strains [37].…”