Post-COVID-19 condition is not only a question of persistent symptoms: structured screening including health-related quality of life reveals two separate clusters of post-COVID

Abstract

Purpose: Some patients experience long-term sequelae after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, despite a present post-COVID condition, defined as "any symptom lasting longer than 12 weeks," only a subset of patients search for medical help and therapy.

Method: We invited all adults with a positive real-time polymerase chain reaction (RT-PCR) for SARS-CoV-2 between March 2020 and September 2021 (n = 4091) in the city of Jena to answer a standardized questionnaire including demographic information, the course of the acute infection and current health status. K-means-clustering of quality of life (QoL) was used to explore post-COVID subgroups.

Results: A total of 909 participants at a median interval of 367 (IQR 291/403) days after acute infection were included in the analysis. Of those, 643 (70.7%) complained of having experienced persistent symptoms at the time of the survey. Cluster analysis based on QoL revealed two subgroups of people with persistent post-COVID symptoms. Whereas 189/643 participants (29.4%) showed markedly diminished QoL, normal QoL was detected in 454/643 individuals (70.6%).

Conclusion: Despite persistent symptoms being reported by nearly three quarters of participants, only one-third of these described a significant reduction in QoL (cluster 1), whereas the other two-thirds reported a near-normal QoL (cluster 2), thus indicating a differentiation between "post-COVID disease" and "post-COVID condition". The prevalence of clinically relevant post-COVID disease was at least 20.7%. Health policies should focus on this subset.

Keywords: Cluster analysis; Differentiation; Post-COVID condition; Post-COVID-19; Prevalence; QoL.

Fig. 1

Participant flow of the survey

Fig. 2

Results of SF-36 itemized by dimensions and component summary scores. A Comparison of the total study group to the German normal data from Study on the Health of Adults in Germany–Wave 1 (DEGS1; n = 7524). B Analysis of the cohort according to persistent symptoms. Both resulting groups are compared with German normal population (DEGS1; n = 7524) and patients with diagnosed post-COVID from our specialized outpatient clinic (n = 431). C Clustering of the group with persistent symptoms according to the SF-36 scores. This clustering indicated two groups: one with significantly diminished QoL (post-COVID disease; n = 189) and a second with near-normal QoL (post-COVID condition; n = 454)

Fig. 3

Frequency of acute (A) and persistent (B) post-COVID-associated symptoms according to cluster classification. The proportions of patients with each symptom are shown (A: 188 participants in cluster 1 and 453 participants in cluster 2, B: fatigue (187/444), sleep disturbance (188/445), pain (181/431), memory impairment (187/441), respiratory problems (187/439), reduced mobility (183/441), dizziness (181/434), muscular problems (180/433), intestinal dysfunction (182/441), tinnitus (180/435), smell impairment (182/439), hair loss (181/442), impaired sense of taste (180/440), vascular occlusion (174/437); *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001)

Fig. 4

Relative frequencies of fatigue and depression according to the FAS and PHQ-9 questionnaires in the total cohort (A) and subgroups according to persistent symptoms (B) and post-COVID cluster classification (C)