fatigue

Fatigue is one of the most common presenting complaints in primary care and poses a significant diagnostic challenge due to its multifactorial aetiology. While the majority of cases are benign and self-limiting, fatigue may also represent an early manifestation of serious underlying pathology. This review distinguishes between acute fatigue, typically transient and associated with intercurrent illness or lifestyle factors, and chronic fatigue, defined as fatigue persisting for six or more weeks, which is more likely to be multifactorial in origin.

This narrative review aims to provide a practical and structured diagnostic framework for general practitioners to evaluate and manage fatigue effectively in the primary care setting.

A narrative review of the literature was conducted using PubMed and Google Scholar. Searches were limited to articles published in English from 2010 onwards. Search terms included "fatigue," "primary care," "chronic fatigue," "myalgic encephalomyelitis," "post-viral fatigue," "sleep disorders," and "functional somatic syndromes." Seminal references predating 2010 were retained where no suitable replacement was available. This review did not employ a formal systematic search strategy, and no risk-of-bias assessment was performed, consistent with the narrative review format.

Fatigue arises from a wide range of physical, psychological, and lifestyle-related causes, best understood through a three-tier classification: primary/idiopathic, secondary, and psychosocial. A systematic approach incorporating thorough history-taking, focused clinical examination, and judicious use of investigations is essential. Identification of red flag symptoms is critical to exclude serious conditions, including malignancy and chronic infections.

A structured, patient-centred approach enables general practitioners to manage fatigue effectively while minimising unnecessary investigations and ensuring timely identification of serious disease.

A 43-year-old woman presented with a 1-year history of recurring symptoms of sudden onset of fatigue, palpitations, dyspnea, chest pain, lightheadedness, and nausea that were associated with standing and resolved with sitting. These symptoms began 1 month after mild COVID-19 infection. At presentation, while supine, blood pressure (BP) was 123/70 mm Hg and heart rate (HR) was 90/min; while seated, BP was 120/80 and HR was 93/min; after standing for 1 minute, BP was 124/80 and HR was 119/min. Physical examination results were normal. Oxygen saturation was 98% at rest while breathing room air. She had no oxygen desaturation during a 6-minute walk test but walked only 282 m (45% predicted). Complete blood cell count, morning cortisol, and thyrotropin blood levels were normal. Electrocardiogram (ECG), chest computed tomography, pulmonary function testing, methacholine challenge, bronchoscopy, echocardiography, and cardiac catheterization findings were normal. During tilt table testing, the patient experienced lightheadedness and nausea when moved from horizontal to the upright position. Results of the tilt table test are shown in the Table and Figure.

Importance: Daytime functional impairments are the primary reasons for patients with insomnia to seek treatment, yet little is known about what the optimal treatment is for improving daytime functions and how best to proceed with treatment for patients whose insomnia has not remitted.

Objectives: To compare the efficacy of behavioral therapy (BT) and zolpidem as initial therapies for improving daytime functions among patients with insomnia and evaluate the added value of a second treatment for patients whose insomnia has not remitted.

Design, setting, and participants: In this sequential multiple-assignment randomized clinical trial conducted at institutions in Canada and the US, 211 adults with chronic insomnia disorder were enrolled between May 1, 2012, and December 31, 2015, and followed up for 12 months. Statistical analyses were performed on an intention-to-treat basis in April and October 2023.

Interventions: Participants were randomly assigned to either BT or zolpidem as first-stage therapy, and those whose insomnia had not remitted received a second-stage psychological therapy (BT or cognitive therapy) or medication therapy (zolpidem or trazodone).

Main outcomes and measures: Study outcomes were daytime symptoms of insomnia, including mood disturbances, fatigue, functional impairments of insomnia, and scores on the 36-item Short-Form Health Survey (SF-36) physical and mental health components.

Results: Among 211 adults with insomnia (132 women [63%]; mean [SD] age, 45.6 [14.9] years), 104 were allocated to BT and 107 to zolpidem at the first stage. First-stage treatment with BT or zolpidem yielded significant and equivalent benefits for most of the daytime outcomes, including depressive symptoms (Beck Depression Inventory-II mean score change, -3.5 [95% CI, -4.7 to -2.3] vs -4.3 [95% CI, -5.7 to -2.9]), fatigue (Multidimensional Fatigue Inventory mean score change, -4.7 [95% CI, -7.3 to -2.2] vs -5.2 [95% CI, -7.9 to -2.5]), functional impairments (Work and Social Adjustment Scale mean score change, -5.0 [95% CI, -6.7 to -3.3] vs -5.1 [95% CI, -7.2 to -2.9]), and mental health (SF-36 mental health subscale mean score change, 3.5 [95% CI, 1.9-5.1] vs 2.5 [95% CI, 0.4-4.5]), while BT produced larger improvements for anxiety symptoms relative to zolpidem (State-Trait Anxiety Inventory mean score change, -4.1 [95% CI, -5.8 to -2.4] vs -1.2 [95% CI, -3.0 to 0.5]; P = .02; Cohen d = 0.55). Second-stage therapy produced additional improvements for the 2 conditions starting with zolpidem at posttreatment in fatigue (Multidimensional Fatigue Inventory mean score change: zolpidem plus BT, -3.8 [95% CI, -7.1 to -0.4]; zolpidem plus trazodone, -3.7 [95% CI, -6.3 to -1.1]), functional impairments (Work and Social Adjustment Scale mean score change: zolpidem plus BT, -3.7 [95% CI, -6.4 to -1.0]; zolpidem plus trazodone, -3.3 [95% CI, -5.9 to -0.7]) and mental health (SF-36 mental health subscale mean score change: zolpidem plus BT, 5.3 [95% CI, 2.7-7.9]; zolpidem plus trazodone, 2.0 [95% CI, 0.1-4.0]). Treatment benefits achieved at posttreatment were well maintained throughout the 12-month follow-up, and additional improvements were noted for patients receiving the BT treatment sequences.

Conclusions and relevance: In this randomized clinical trial of adults with insomnia disorder, BT and zolpidem produced improvements for various daytime symptoms of insomnia that were no different between treatments. Adding a second treatment offered an added value with further improvements of daytime functions.

Trial registration: ClinicalTrials.gov Identifier: NCT01651442.

Background
Long-COVID refers to a variety of symptoms affecting different organs reported by people following Coronavirus Disease 2019 (COVID-19) infection. To date, there have been no robust estimates of the incidence and co-occurrence of long-COVID features, their relationship to age, sex, or severity of infection, and the extent to which they are specific to COVID-19. The aim of this study is to address these issues.

Methods and findings
We conducted a retrospective cohort study based on linked electronic health records (EHRs) data from 81 million patients including 273,618 COVID-19 survivors. The incidence and co-occurrence within 6 months and in the 3 to 6 months after COVID-19 diagnosis were calculated for 9 core features of long-COVID (breathing difficulties/breathlessness, fatigue/malaise, chest/throat pain, headache, abdominal symptoms, myalgia, other pain, cognitive symptoms, and anxiety/depression). Their co-occurrence network was also analyzed. Comparison with a propensity score–matched cohort of patients diagnosed with influenza during the same time period was achieved using Kaplan–Meier analysis and the Cox proportional hazard model. The incidence of atopic dermatitis was used as a negative control.

Among COVID-19 survivors (mean [SD] age: 46.3 [19.8], 55.6% female), 57.00% had one or more long-COVID feature recorded during the whole 6-month period (i.e., including the acute phase), and 36.55% between 3 and 6 months. The incidence of each feature was: abnormal breathing (18.71% in the 1- to 180-day period; 7.94% in the 90- to180-day period), fatigue/malaise (12.82%; 5.87%), chest/throat pain (12.60%; 5.71%), headache (8.67%; 4.63%), other pain (11.60%; 7.19%), abdominal symptoms (15.58%; 8.29%), myalgia (3.24%; 1.54%), cognitive symptoms (7.88%; 3.95%), and anxiety/depression (22.82%; 15.49%). All 9 features were more frequently reported after COVID-19 than after influenza (with an overall excess incidence of 16.60% and hazard ratios between 1.44 and 2.04, all p < 0.001), co-occurred more commonly, and formed a more interconnected network. Significant differences in incidence and co-occurrence were associated with sex, age, and illness severity. Besides the limitations inherent to EHR data, limitations of this study include that (i) the findings do not generalize to patients who have had COVID-19 but were not diagnosed, nor to patients who do not seek or receive medical attention when experiencing symptoms of long-COVID; (ii) the findings say nothing about the persistence of the clinical features; and (iii) the difference between cohorts might be affected by one cohort seeking or receiving more medical attention for their symptoms.

Conclusions
Long-COVID clinical features occurred and co-occurred frequently and showed some specificity to COVID-19, though they were also observed after influenza. Different long-COVID clinical profiles were observed based on demographics and illness severity.

Author summary
Why was this study done?
Long-COVID has been described in recent studies. But we do not know the risk of developing features of this condition and how it is affected by factors such as age, sex, or severity of infection.
We do not know if the risk of having features of long-COVID is more likely after Coronavirus Disease 2019 (COVID-19) than after influenza.
We do not know about the extent to which different features of long-COVID co-occur.
What did the researchers do and find?
This research used data from electronic health records of 273,618 patients diagnosed with COVID-19 and estimated the risk of having long-COVID features in the 6 months after a diagnosis of COVID-19. It compared the risk of long-COVID features in different groups within the population and also compared the risk to that after influenza.
The research found that over 1 in 3 patients had one or more features of long-COVID recorded between 3 and 6 months after a diagnosis of COVID-19. This was significantly higher than after influenza.
For 2 in 5 of the patients who had long-COVID features in the 3- to 6-month period, they had no record of any such feature in the previous 3 months.
The risk of long-COVID features was higher in patients who had more severe COVID-19 illness, and slightly higher among females and young adults. White and non-white patients were equally affected.
What do these findings mean?
Knowing the risk of long-COVID features helps in planning the relevant healthcare service provision.
The fact that the risk is higher after COVID-19 than after influenza suggests that their origin might, in part, directly involve infection with SARS-CoV-2 and is not just a general consequence of viral infection. This might help in developing effective treatments against long-COVID.
The findings in the subgroups, and the fact that the majority of patients who have features of long-COVID in the 3- to 6-month period already had symptoms in the first 3 months, may help in identifying those at greatest risk.