Review The demographic features of fatigue in the general population worldwide: a systematic review and meta-analysis 2023 Yoon et al

Background: Fatigue is one of the most common subjective symptoms that impairs daily life and predict health-related events. This study aimed to estimate the prevalence of fatigue in the global population.

Methods: PubMed and the Cochrane Library were used to search for relevant articles from inception to December 31, 2021. Studies with prevalence data of fatigue in the general population were selected and reviewed by three authors independently and cross-checked. Regarding subgroups, adults (≥18 years), minors (<18 years), and specific occupation population (participants in each study being limited to a specific occupational group), and fatigue types and severity, meta-analysis was conducted to produce point estimates and 95% confidence intervals (95% CI).

Results: From the initial 3,432 studies, 91 studies accounting for 115 prevalence data points (623,624 participants) were finally selected. The prevalence of general fatigue (fatigue lasting < 6 months, or fatigue of unspecified duration) was 20.4% (95% CI, 16.7–25.0) in adults, 11.7% (95% CI, 5.2–26.6) in minors, and 42.3% (95% CI, 33.0–54.2) in specific occupations. Chronic fatigue (fatigue lasting more than 6 months) affected 10.1% (95% CI, 8.2–12.5) of adults, 1.5% (95% CI, 0.5–4.7) of minors, and 5.5% (95% CI, 1.4–21.6) of subjects in specific occupations. There was an overall female-predominant prevalence for all subgroup analyses, with a total odds ratio of 1.4 (95% CI, 1.3–1.6). Regarding the severity and presence of medical causes, the total prevalence of moderate fatigue [14.6% (95% CI, 9.8–21.8)] was 2.4-fold that of severe fatigue [6.1% (95% CI, 3.4–11.0)], while unexplained fatigue (fatigue experienced by individuals without any underlying medical condition that can explain the fatigue) was ~2.7-fold that of explained fatigue (fatigue experienced by individuals with a medical condition that can explain the fatigue); as proportion of 40.0% of physical, 8.6% of mental, and 28.4% of mixed cause.

Conclusions: This study has produced the first comprehensive picture of global fatigue prevalence in the general population, which will provide vital reference data contributing to fatigue-related research, including the prevention of diseases.

Open access, https://www.frontiersin.org/articles/10.3389/fpubh.2023.1192121/full

 

Given that "fatigue" isn't clearly defined, and "fatigue" is presently not quantifiable and perception of "fatigue" varies greatly from person to person, how are their numbers a "vital reference"?

 

Chronic fatigue vs CFS and possible confusion between the two.

The one potentially useful figure from this review is for the 9 studies (84.5k participants) of adults surveyed for both chronic fatigue (>6mo) and "CFS or CFS-like illnesses". (Note mostly questionnaire based of a general population).

Prevalence:
Chronic fatigue, 10.1% (57% Female)
Within that 10% figure
CFS/CFS-like 1.9%
The CFS/CFS-like self-report looks about right to me. However, the best evidence is that the true prevalence of MEcfs is no more than 0.5% (pre-Covid, when these surveys were mostly done).

That would give a prevalence of 10% for CF vs 0.5% for CFS, a 20:1 ratio.

This matters when people are selected for a study purely on the basis of a Q such as "has a doctor ever told you you have ME or chronic fatigue syndrome?

You wouldn't need many people with CF misremembering a chronic fatigue diagnosis (10% of pop) as CFS to mess up a questionnaire-diagnosed cohort. E.g. UK biobank MEcfs cohort - though the risk of it is not the same as saying that is what has happened.