Category: Epidemiology

How common is chronic fatigue syndrome; how long is a piece of string?

Comment on: Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. [Popul Health Metr. 2007]

One of the most difficult tasks in medicine is to accurately measure how common illnesses are. Why do we do it? Justifications include being able to plan health care and public health priorities, as well as highlighting specific diseases for extra funding for both health care and research. Yet the jobbing physician at the sharp edge of clinical practice cares little about the exact prevalence of a disease or illness, since this is all too obvious from the frequency of the problems presented by patients who come through the door.

You can read the rest of this comment here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1904177/

 

Source: White PD. How common is chronic fatigue syndrome; how long is a piece of string? Popul Health Metr. 2007 Jun 8;5:6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1904177/ (Full article)

 

Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia

Abstract:

BACKGROUND: Chronic fatigue syndrome (CFS) is a debilitating illness with no known cause or effective therapy. Population-based epidemiologic data on CFS prevalence are critical to put CFS in a realistic context for public health officials and others responsible for allocating resources.

METHODS: Based on a random-digit dialing survey we ascertained CFS cases and controls to estimate the prevalence of CFS in metropolitan, urban, and rural populations of Georgia. This report focuses on the 5,623 of 19,381 respondents ages 18 to 59 years old. Fatigued (2,438), randomly selected unwell not fatigued (1,429) and randomly selected well (1,756) respondents completed telephone questionnaires concerning fatigue, other symptoms, and medical history. Subsets of those identified by interview as having CFS-like illness (292), chronic unwellness which was not CFS-like (268 – randomly selected), and well subjects (223, matched to those with CFS-like illness on sex, race, and age) completed a clinical evaluation.

RESULTS: We estimated that 2.54% of persons 18 to 59 years of age suffered from CFS. There were no significant differences in prevalence of CFS between metropolitan, urban or rural populations or between white and black residents of the three regions. However, there were significant differences in female-to-male ratios of prevalence across the strata (metropolitan female: male 11.2 : 1, urban 1.7 : 1, rural 0.8 : 1).

CONCLUSION: We estimated that 2.54% of the Georgia population suffers from CFS, which is 6- to 10-fold higher than previous population-based estimates in other geographic areas. These differences may reflect broader screening criteria and differences in the application of the case definition. However, we cannot exclude the possibility that CFS prevalence may be higher in Georgia than other areas where it has been measured. Although the study did not identify differences in overall prevalence between metropolitan, urban, and rural Georgia populations, it did suggest the need for additional stratified analyses by geographic strata.

Comment in: How common is chronic fatigue syndrome; how long is a piece of string? [Popul Health Metr. 2007]

 

Source: Reeves WC, Jones JF, Maloney E, Heim C, Hoaglin DC, Boneva RS, Morrissey M, Devlin R. Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. Popul Health Metr. 2007 Jun 8;5:5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1904178/ (Full article)

 

The prevalence of chronic fatigue syndrome in Nigeria

Abstract:

The present study found adult rates of chronic fatigue syndrome (CFS) in Nigeria that were somewhat higher than rates from community-based CFS epidemiologic studies in the USA. The rates of chronic fatigue for both adults and children were also higher than in existing community-based studies. It is possible that the presence of several fatiguing illnesses such as malaria and typhoid, the lack of adequate healthcare resources and poverty in Nigeria, place individuals at greater risk for fatigue and its syndromes. There is a need for more epidemiologic studies on the prevalence and sociodemographic characteristics of CFS in developing countries.

 

Source: Njoku MG, Jason LA, Torres-Harding SR. The prevalence of chronic fatigue syndrome in Nigeria. J Health Psychol. 2007 May;12(3):461-74. https://www.ncbi.nlm.nih.gov/pubmed/17439996

 

Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study

Abstract:

OBJECTIVE: To delineate the risk factors, symptom patterns, and longitudinal course of prolonged illnesses after a variety of acute infections.

DESIGN: Prospective cohort study following patients from the time of acute infection with Epstein-Barr virus (glandular fever), Coxiella burnetii (Q fever), or Ross River virus (epidemic polyarthritis).

SETTING: The region surrounding the township of Dubbo in rural Australia, encompassing a 200 km geographical radius and 104,400 residents.

PARTICIPANTS: 253 patients enrolled and followed at regular intervals over 12 months by self report, structured interview, and clinical assessment.

OUTCOME MEASURES: Detailed medical, psychiatric, and laboratory evaluations at six months to apply diagnostic criteria for chronic fatigue syndrome. Premorbid and intercurrent illness characteristics recorded to define risk factors for chronic fatigue syndrome. Self reported illness phenotypes compared between infective groups.

RESULTS: Prolonged illness characterised by disabling fatigue, musculoskeletal pain, neurocognitive difficulties, and mood disturbance was evident in 29 (12%) of 253 participants at six months, of whom 28 (11%) met the diagnostic criteria for chronic fatigue syndrome. This post-infective fatigue syndrome phenotype was stereotyped and occurred at a similar incidence after each infection. The syndrome was predicted largely by the severity of the acute illness rather than by demographic, psychological, or microbiological factors.

CONCLUSIONS: A relatively uniform post-infective fatigue syndrome persists in a significant minority of patients for six months or more after clinical infection with several different viral and non-viral micro-organisms. Post-infective fatigue syndrome is a valid illness model for investigating one pathophysiological pathway to chronic fatigue syndrome.

 

Source: Hickie I, Davenport T, Wakefield D, Vollmer-Conna U, Cameron B, Vernon SD, Reeves WC, Lloyd A; Dubbo Infection Outcomes Study Group. Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study. BMJ. 2006 Sep 16;333(7568):575. Epub 2006 Sep 1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569956/ (Full article)

 

Mortality in a cohort of chronically fatigued patients

Abstract:

BACKGROUND: Comprehensive studies of mortality among patients with chronic fatigue (CF) and chronic fatigue syndrome (CFS) have not been published, but several sources suggest that CFS is associated with an elevated risk for suicide.

METHOD: Data on 1201 chronically fatigued patients followed in a university-affiliated tertiary-care clinic for up to 14 years were submitted to the Center for Disease Control and Prevention (CDC) National Death Index (NDI) to evaluate all-cause and suicide-caused death rates against standardized mortality rates (SMRs). We used Life Table Analysis to examine the influence of sex and diagnoses of CFS and depression.

RESULTS: All-cause mortality in chronically fatigued patients was no higher than expected, but suicide-caused death rates were more than eight times higher than in the US general population. The significant elevation in the SMR of suicide was restricted to those who did not meet criteria for CFS [SMR(CF)=14.2, 95% confidence interval (CI) 5.7-29.3 versus SMR(CFS)=3.6, 95% CI 0.4-12.9]. Among chronically fatigued patients who did not meet CFS criteria, those with a lifetime history of major depression (MD) had higher suicide-caused death rates than among their non-depressed counterparts (SMR(MD)=19.1, 95% CI 7.0-41.5 versus SMR(NMD)=5.6, 95% CI 0.1-31.4), although the difference was not significant.

CONCLUSIONS: CFS does not appear to be associated with increased all-cause mortality or suicide rates. Clinicians, however, should carefully evaluate patients with CF for depression and suicidality.

 

Source: Smith WR, Noonan C, Buchwald D. Mortality in a cohort of chronically fatigued patients. Psychol Med. 2006 Sep;36(9):1301-6. https://www.ncbi.nlm.nih.gov/pubmed/16893495

 

Causes of death among patients with chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is a debilitating illness affecting thousands of individuals. At the present time, there are few studies that have investigated causes of death for those with this syndrome. The authors analyzed a memorial list tabulated by the National CFIDS Foundation of 166 deceased individuals who had had CFS. There were approximately three times more women than men on the list.

The three most prevalent causes of death were heart failure, suicide, and cancer, which accounted for 59.6% of all deaths. The mean age of those who died from cancer and suicide was 47.8 and 39.3 years, respectively, which is considerably younger than those who died from cancer and suicide in the general population. The implications of these findings are discussed.

 

Source: Jason LA, Corradi K, Gress S, Williams S, Torres-Harding S. Causes of death among patients with chronic fatigue syndrome. Health Care Women Int. 2006 Aug;27(7):615-26. https://www.ncbi.nlm.nih.gov/pubmed/16844674

 

Chronic fatigue in a population sample: definitions and heterogeneity

Abstract:

BACKGROUND: Numerous nosological decisions are made when moving from the common human symptom of unusual fatigue to the rare chronic fatigue syndrome (CFS). These decisions have infrequently been subjected to rigorous evaluation.

METHOD: We obtained telephone interview data on fatiguing symptoms from 31406 individuals twins in the Swedish Twin Registry aged 42-64 years; 5330 subjects who endorsed fatigue and possessed no exclusionary condition formed the analytic group. We evaluated the definition and classification of CFS-like illness using graphical methods, regression models, and latent class analysis.

RESULTS: Our results raise fundamental questions about the 1994 Centers for Disease Control criteria as (1) there was no empirical support for the requirement of four of eight cardinal CFS symptoms; (2) these eight symptoms were not equivalent in their capacity to predict fatigue; and (3) no combination of symptoms was markedly more heritable. Critically, latent class analysis identified a syndrome strongly resembling CFS-like illness.

CONCLUSIONS: Our data are consistent with the ‘existence’ of CFS-like illness although the dominant nosological approach captures population-level variation poorly. We suggest that studying a more parsimonious case definition – impairing chronic fatigue not due to a known cause – would represent a way forward.

 

Source: Sullivan PF, Pedersen NL, Jacks A, Evengård B. Chronic fatigue in a population sample: definitions and heterogeneity. Psychol Med. 2005 Sep;35(9):1337-48. http://www.ncbi.nlm.nih.gov/pubmed/16168156

 

Twin analyses of chronic fatigue in a Swedish national sample

Abstract:

BACKGROUND: Chronic fatigue has infrequently been studied in twins. Data from twin studies can inform clinical and research approaches to the management and etiology of human complex traits.

METHOD: The authors obtained telephone interview data on current chronic fatigue from 31406 individuals twins in the Swedish Twin Registry (aged 42-64 years, 75.68% response rate), from both members of 12407 pairs and from one member of 6592 pairs. Of the complete pairs, 3269 pairs were monozygotic, 9010 pairs dizygotic, and 128 pairs of unknown zygosity. Structural equation twin modeling was used to estimate the latent genetic architecture of varying definitions of fatiguing illness.

RESULTS: Estimates of additive genetic effects, shared environmental effects, and individual-specific environmental effects were similar in males and females. No definition of current fatiguing illness (ranging from any fatigue to CFS-like illness) was strikingly distinctive. Individual-specific effects were the predominant source of variation, followed by modest genetic influences. We could not exclude a small but conceptually important contribution of shared environmental effects.

CONCLUSIONS: Current fatiguing illness appears to be a complex trait resulting from both environmental and genetic sources of variation without pronounced differences by gender.

 

Source: Sullivan PF, Evengård B, Jacks A, Pedersen NL. Twin analyses of chronic fatigue in a Swedish national sample. Psychol Med. 2005 Sep;35(9):1327-36. http://www.ncbi.nlm.nih.gov/pubmed/16168155

 

The epidemiology of chronic fatigue in the Swedish Twin Registry

Abstract:

BACKGROUND: Chronic fatigue syndrome (CFS) remains an idiopathic and controversial entity.

METHOD: We screened 31405 individual members of the Swedish Twin Registry (aged 42-64 years) for the symptoms of fatiguing illness via a telephone questionnaire. We refined self-reported symptoms via data from several national registries and from physician review of all available medical records in order to approximate closely the dominant case definition of CFS.

FINDINGS: The 6-month prevalence of CFS-like illness was 2.36% (95% CI 2.19-2.53) and was markedly higher in women than men, odds ratio 3.92 (95% CI 3.24-4.72) with no significant association with age or years of education. There was a highly significant association with occupation that disappeared after accounting for gender.

INTERPRETATION: CFS-like illness may be more common that previously acknowledged. There is a marked increase in risk by gender. Previous reports that CFS is more prevalent in individuals in certain occupational categories were not confirmed and may have been due to confounding by gender.

 

Source: Evengård B, Jacks A, Pedersen NL, Sullivan PF. The epidemiology of chronic fatigue in the Swedish Twin Registry. Psychol Med. 2005 Sep;35(9):1317-26. http://www.ncbi.nlm.nih.gov/pubmed/16168154

 

A preliminary epidemiological study and discussion on traditional Chinese medicine pathogenesis of chronic fatigue syndrome in Hong Kong

Abstract:

OBJECTIVE: Our purpose is to conduct an epidemiological study of chronic fatigue syndrome (CFS) and its syndrome types and symptoms of traditional Chinese medicine (TCM) among adults (20-50 years old) in Hong Kong, and to discuss the TCM pathogenesis.

METHODS: DESIGN: Cross-sectional questionnaire survey.

MEASURES: Demographic data, CDC (1994) CFS diagnostic criteria, Trudie Chalder fatigue scale, and China national standard for TCM syndrome types criteria.

SUBJECTS: Twenty to fifty years old adults by convenient sampling.

RESULTS: One thousand and thirteen subjects were successfully interviewed. Five hundred and eighty-five subjects (57.8%) had different levels of fatigue. Sixty-five subjects (6.4%) met CFS diagnostic criteria. In terms of TCM syndrome types, blood stasis due to qi deficiency had the highest prevalence (35.7%) among CFS. In the 54 symptoms investigated in total, the first eight symptoms in order of appearing rates were soreness of loins and weakness in knees, poor spirit, lassitude, pain, insomnia, forgetting, vessels blood stasis, vertigo and dazzle. The mostly appeared tongue figures were pale and corpulent or pale dim tongue proper, white and white greasy tongue coating, and the mostly appeared pulse figure was sunken-thin.

CONCLUSION: The point prevalence of CFS among adults of 20 to 50 years old was found to be 6.4%. The most prevalent TCM syndrome type was blood stasis due to qi deficiency. The TCM pathogenesis of CFS was deficiency of origin, mainly deficiency of qi and kidney, with excess of superficiality.

 

Source: Yiu YM, Qiu MY. A preliminary epidemiological study and discussion on traditional Chinese medicine pathogenesis of chronic fatigue syndrome in Hong Kong. Zhong Xi Yi Jie He Xue Bao. 2005 Sep;3(5):359-62. [Article in Chinese] http://www.ncbi.nlm.nih.gov/pubmed/16159567 View full article in Chinese here: http://www.jcimjournal.com/articles/publishArticles/pdf/200632947810378.pdf