Beyond exhaustion: study identifies fatigue as key factor limiting functionality in long COVID patients

In a recent study published in BMJ Open, researchers assess self-documented post-coronavirus disease 2019 (COVID-19) syndrome (PCS) or long COVID symptoms among care-seeking individuals. The impact of PCS symptoms on work abilities and health-related quality of life (HRQoL) was also determined.

Study: Impact of fatigue as the primary determinant of functional limitations among patients with post-COVID-19 syndrome: a cross-sectional observational study. Image Credit: fizkes/

About the study

PCS refers to the symptoms and signs of COVID-19 that persist beyond 12 weeks of the acute infection. The increasing prevalence of long COVID has raised international health concerns due to the number of individuals affected and related morbidities. PCS symptoms such as breathlessness, fatigue, anosmia, and brain fog can cause debilitating psychological limitations.

In the present cross-sectional observational study, researchers present the baseline symptomatology and functional impairments among treatment-seeking long COVID patients and reported different patient-documented symptoms that contributed to these impairments.

The study included 3,754 long COVID patients 18 years and older who used the Living with COVID Recovery (LWCR) digital health intervention (DHI) as part of their treatment across 31 specialized long COVID clinics in Wales and England. The primary outcome of the study was changes in the Work and Social Adjustment Scale (WSAS), which assessed functional impairments among the patients.

Other symptoms included fatigue, anxiety, depression, cognitive impairments, breathlessness, and HRQoL. Fatigue was assessed using the reversed Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), whereas anxiety and depression were assessed using the seven-item Generalised Anxiety Disorder (GAD-7) scale and eight-item Patient Health Questionnaire (PHQ-8), respectively.

The five-item Perceived Deficits Questionnaire (PDQ-5) was used to assess cognitive impairments, whereas the Medical Research Council (MRC) Dyspnea Scale and Dyspnoea-12 (D-12) questionnaire were used to evaluate breathlessness. HR-QoL was evaluated using the EQ-5D, which measures self-care, mobility, routine activities, discomfort or pain, and depression or anxiety.

WSAS scores over 20 indicated moderately severe-intensity functional impairments. LWCR users also completed study-specific questionnaires to provide data on the number of sick days from work in the four weeks before completing the questionnaires.

Logistic regression modelling identified patient-reported outcome measures (PROMs) related to high WSAS scores and calculated the odds ratios (ORs), adjusting for covariates such as age and sex. Individuals over the age of 18 registered for LWCR DHI as part of the care provided in long COVID NHS community clinics between November 30, 2020, and March 23, 2022. All study participants had access to smartphone devices, could read English, and were considered suitable for rehabilitation.

Study findings

Among the study participants, 94% were between 18 and 65 years of age, with a mean participant age of 48. Moreover, 71% of the study cohort were women, 87% were White, and 53% had attained degree-level education. Fifty-one percent of the study participants lost one or more work days in the preceding four weeks, whereas 20% could not resume work.

The mean WSAS score was 21, with 53% of the cohort scoring over 20. Fatigue, cognitive impairments, and depression were significantly related to WSAS scores equal to or above 20, with fatigue being the strongest predictor of high WSAS scores. In addition, the reversed FACIT-F scores significantly predicted EQ-5D scores, thus indicating that fatigue had a considerable impact on the QoL of long COVID patients.

Functional impairments were reported for all WSAS categories, with the highest rates for the workability and social leisure activities domains, with mean scores of 4.60 and 4.70, respectively. The close relationships domain was affected the least, with a mean score of three.

The mean EQ-5D score was 0.6, with the discomfort/pain and depression/anxiety domains most affected, and the mean FACIT-F score was 19.60. The mean GAD-7, PHQ-8, Dyspnoea-12, and PDQ-5 scores were 9.0, 11.80, 12, and 12, respectively. Among the study participants, the median MRC Dyspnoea Scale score was two.

A single point elevation in the reversed FACIT-F scores increased the likelihood of high WSAS scores by 16%. Non-significant differences in functional impairments were observed between males and females.

Most functional impairments were observed among young adults. The highest rate of functional impairments was noted for individuals between 30 to 39 years of age as compared to those between 18 and 29 years of age.

Functional impairments reported by long COVID patients were worse than those reported in patients with a history of stroke and similar to those in Parkinson’s disease patients, both of which are debilitating neurological conditions. The study participants documented higher fatigue levels than individuals with a history of stroke, end-stage renal disease, inflammatory bowel disease, and malignancy patients, with mean scores of 38, 39, 39, and 24, respectively.


The study findings indicate that treatment-seeking long COVID patients, most of whom were White, female, well-educated, and working individuals, experience considerable functional impairments and low HRQoL. These impairments are primarily the result of PCS-associated fatigue, which significantly affected their work abilities and performance of routine activities.

Clinical rehabilitation and care programs are urgently needed to address fatigue management and improve functionality among PCS patients.

Journal reference:
Pooja Toshniwal Paharia

Written by

Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.


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