Tag: Unger

Physiological assessment of orthostatic intolerance in chronic fatigue syndrome

Abstract:

Background: Orthostatic intolerance-OI is common in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-ME/CFS. We used a 10-min passive vertical lean test as orthostatic challenge-OC and measured changes in vitals and end tidal CO2 (eTCO2). An abnormal physiologic response to OC was identified in 60% of the 63 patients evaluated from one to three times over several years. Hypocapnia, either resting or induced by OC, was the most frequent abnormality, followed by postural orthostatic tachycardia.

Objective: Evaluate the physiologic response of patients with ME/CFS to a standardized OC.

Design: Respiratory and heart rate, blood pressure and eTCO2 were recorded twice at the end of 10-min supine rest and then every minute during the 10-min lean. Hypocapnia was eTCO2 ≤ 32 mmHg. Orthostatic tachycardia was heart rate increase ≥ 30 beats per minute compared with resting or ≥ 120 BPM. Orthostatic hypotension was decreased systolic pressure ≥ 20 mmHg from baseline. Tachypnea was respiratory rate of ≥ 20 breaths per minute-either supine or leaning. Questionnaire data on symptom severity, quality of life and mood were collected at visit #2.

Patients: 63 consecutive patients fulfilling the 1994 case definition for CFS underwent lean testing at first visit and then annually at visit 2 (n = 48) and 3 (n = 29).

Measures: Supine hypocapnia; orthostatic tachycardia, hypocapnia or hypotension.

Results: The majority of ME/CFS patients (60.3%, 38/63) had an abnormality detected during a lean test at any visit (51%, 50% and 45% at visits 1, 2 and 3, respectively). Hypocapnia at rest or induced by OC was more common and more likely to persist than postural orthostatic tachycardia. Anxiety scores did not differ between those with and without hypocapnia.

Conclusions: The 10-min lean test is useful in evaluation of OI in patients with ME/CFS. The most frequent abnormality, hypocapnia, would be missed without capnography.

Source: Natelson BH, Lin JS, Blate M, Khan S, Chen Y, Unger ER. Physiological assessment of orthostatic intolerance in chronic fatigue syndrome. J Transl Med. 2022 Feb 16;20(1):95. doi: 10.1186/s12967-022-03289-8. PMID: 35172863. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-022-03289-8 (Full study)

Evaluation of natural killer cell assay performance on shipped blood specimens

Abstract:

Documenting the importance of NK cell function as a biomarker for diseases and physiologic conditions including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), will require assays amenable to clinical implementation and standardization. Research studies typically perform NK functional assays on the day of sample collection. This pilot study was conducted to compare assay formats and specimen processing to identify those that are most tolerant of conditions required for shipping and amenable to standardization as shown by inter-assay and inter-laboratory correlation of results.

We compared performance within and between assays that measure NK cell function using direct cytotoxicity [chromium-51 release (CRCA) or fluorescence (Flow Cytometry Cytotoxicity Assay, FCCA)] or an indirect surrogate marker (CD107a surface expression)]. Additional variables for within/between assay comparisons included time of testing (same day as specimen collection or next day within 24 h), specimen types [whole blood or isolated peripheral blood mononuclear cells (PBMCs)], and processing method (fresh or cryopreserved). Statistical measures included number of samples tested in assay conditions (n), medians (x͂), interquartile range (IQR), Pearson correlation coefficient (R2), and correlation p-value (p).

Samples came from 3 clinics and included 31 participants. Same day testing was only available for the subset of participants enrolled from the site of the laboratory performing CRCA. Results from same day CRCA testing of whole blood were considered the gold standard [n = 10, x͂=10.0%, IQR = 7.2%], and correlated well with PBMCs isolated next day [n = 26, x͂= 15.6%, IQR = 13.1%] [R2 = 0.59, p = 0.03]. Next day CRCA results were compromised using whole blood or frozen PBMCs. Next day FCCA cytotoxicity in PBMC [n = 30, x͂=34.1%, IQR = 15.5%] correlated with same day CRCA PMBC [R2 = 0.8, p = 0.001] and next day CRCA PMBC [R2 = 0.5, p < 0.0001]. CD107a expression after induction by PMA and ionomycin did not correlate with other cytotoxicity measures. NK function can be measured in PBMCs isolated after overnight shipping/storage at ambient temperature and CRCA and FCCA results on this sample type are well correlated.

Source: Querec TD, Abrams J, Stewart JJ, Barnes Z, Balbin E, Klimas N, Fletcher MA, Brown L, Bertolli J, Unger ER. Evaluation of natural killer cell assay performance on shipped blood specimens. J Immunol Methods. 2021 Apr 2:113049. doi: 10.1016/j.jim.2021.113049. Epub ahead of print. PMID: 33819446. https://pubmed.ncbi.nlm.nih.gov/33819446/

The Effect of Comorbid Medical and Psychiatric Diagnoses on Chronic Fatigue Syndrome

Abstract:

OBJECTIVE: To determine if presence of co-existing medically unexplained syndromes or psychiatric diagnoses affect symptom frequency, severity or activity impairment in Chronic Fatigue Syndrome.

PATIENTS: Sequential Chronic Fatigue Syndrome patients presenting in one clinical practice.

DESIGN: Participants underwent a psychiatric diagnostic interview and were evaluated for fibromyalgia, irritable bowel syndrome and/or multiple chemical sensitivity.

RESULTS: Current and lifetime psychiatric diagnosis was common (68%) increasing mental fatigue/health but not other illness variables and not with diagnosis of other medically unexplained syndromes. 81% of patients had at least one of these conditions with about a third having all three co-existing syndromes. Psychiatric diagnosis was not associated with their diagnosis. Increasing the number of these unexplained conditions was associated with increasing impairment in physical function, pain and rates of being unable to work.

CONCLUSIONS: Patients with Chronic Fatigue Syndrome should be evaluated for current psychiatric conditions because of their impact on patient quality of life, but they do not act as a symptom multiplier for the illness. Other co-existing medically unexplained syndromes are more common than psychiatric co-morbidities in patients presenting for evaluation of medically unexplained fatigue and are also more associated with increased disability and the number and severity of symptoms.

Key Messages: When physicians see patients with medically unexplained fatigue, they often infer that this illness is due to an underlying psychiatric problem. This paper shows that the presence of co-existing psychiatric diagnoses does not impact on any aspect of the phenomenology of medically unexplained fatigue also known as chronic fatigue syndrome. Therefore, psychiatric status is not an important causal contributor to CFS. In contrast, the presence of other medically unexplained syndromes [irritable bowel syndrome; fibromyalgia and/or multiple chemical sensitivity] do impact on the illness such that the more of these that co-exist the more health-related burdens the patient has.

Source: Natelson BH, Lin JS, Lange G, Khan S, Stegner A, Unger ER. The Effect of Comorbid Medical and Psychiatric Diagnoses on Chronic Fatigue Syndrome. Ann Med. 2019 Oct 23:1-18. doi: 10.1080/07853890.2019.1683601. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/31642345

Endometriosis as a Comorbid Condition in Chronic Fatigue Syndrome (CFS): Secondary Analysis of Data From a CFS Case-Control Study

Abstract:

Background: Endometriosis (EM) is a recognized co-morbid condition in women with chronic fatigue syndrome (CFS). This analysis evaluates the impact of EM on the health of women with CFS by comparing selected health characteristics and laboratory parameters in women with CFS with and without EM (CFS+EM and CFS-only).

Methods: This secondary analysis included all 36 women with CFS from a cross-sectional study of CFS in Wichita, KS, conducted between 2002 and 2003. The health characteristics and laboratory parameters of interest included functioning, fatigue, CFS-related symptoms, gynecologic history, routine laboratory parameters, inflammatory markers, cortisol levels, allostatic load, and sleep parameters (overnight polysomnography). We used parametric or non-parametric tests to compare group differences in the selected health characteristics and laboratory parameters. For examining the association between EM and variables of interest, logistic regression models were performed and odds ratios (OR) with 95% confidence intervals (CI) were reported for the magnitude of associations. Statistical significance was set at 0.05 (two-sided).

Results: The mean age of this study sample was 50.9 years. Of women with CFS, 36.1% reported having EM. Age and body mass index (BMI) did not differ between CFS+EM and CFS-only groups. When examining the impact of EM, compared to women with CFS-only, women with both CFS and EM were more likely to report chronic pelvic pain [OR = 9.00 (95% CI, 1.47-55.25)] and hysterectomy [OR = 10.3 (1.82-58.39)], had more CFS symptoms (6.8 ± 0.3 vs. 5.5 ± 0.3, p = 0.02), younger mean age at menopause onset (36.4 ± 3.0 vs. 47.0 ± 2.7 years, p = 0.03), higher mean number of obstructive apnea episodes per hour (20.3 vs. 4.4, p = 0.05) and reported more negative life events (15.8 vs. 4.4, p = 0.05). Other parameters did not differ significantly between the two groups.

Conclusions: We found more than a third of women with CFS reported endometriosis as a comorbid condition. The endometriosis comorbidity was associated with chronic pelvic pain, earlier menopause, hysterectomy, and more CFS-related symptoms. However, endometriosis in women with CFS did not appear to further impact functioning, fatigue, inflammatory markers, or other laboratory parameters. Further investigations including younger women are warranted.

Source: Boneva RS, Lin JS, Wieser F, Nater UM, Ditzen B, Taylor RN, Unger ER. Endometriosis as a Comorbid Condition in Chronic Fatigue Syndrome (CFS): Secondary Analysis of Data From a CFS Case-Control Study. Front Pediatr. 2019 May 21;7:195. doi: 10.3389/fped.2019.00195. eCollection 2019. https://www.ncbi.nlm.nih.gov/pubmed/31179251

Association of chronic fatigue syndrome with premature telomere attrition

Abstract:

Background: Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a severely debilitating condition of unknown etiology. The symptoms and risk factors of ME/CFS share features of accelerated aging implicated in several diseases. Using telomere length as a marker, this study was performed to test the hypothesis that ME/CFS is associated with accelerated aging.

Methods: Participant (n = 639) data came from the follow-up time point of the Georgia CFS surveillance study. Using the 1994 CFS Research Case Definition with questionnaire-based subscale thresholds for fatigue, function, and symptoms, participants were classified into four illness groups: CFS if all criteria were met (n = 64), CFS-X if CFS with exclusionary conditions (n = 77), ISF (insufficient symptoms/fatigue) if only some criteria were met regardless of exclusionary conditions (n = 302), and NF (non-fatigued) if no criteria and no exclusionary conditions (n = 196). Relative telomere length (T/S ratio) was measured using DNA from whole blood and real-time PCR. General linear models were used to estimate the association of illness groups or T/S ratio with demographics, biological measures and covariates with significance set at p < 0.05.

Results: The mean T/S ratio differed significantly by illness group (p = 0.0017); the T/S ratios in CFS (0.90 ± 0.03) and ISF (0.94 ± 0.02) were each significantly lower than in NF (1.06 ± 0.04). Differences in T/S ratio by illness groups remained significant after adjustment for covariates of age, sex, body mass index, waist–hip ratio, post-exertional malaise and education attainment. Telomere length was shorter by 635, 254 and 424 base pairs in CFS, CFS-X and ISF, respectively, compared to NF. This shorter telomere length translates to roughly 10.1–20.5, 4.0–8.2 and 6.6–13.7 years of additional aging in CFS, CFS-X and ISF compared to NF respectively. Further, stratified analyses based on age and sex demonstrated that the association of ME/CFS with short telomeres is largely moderated by female subjects < 45 years old.

Conclusions: This study found a significant association of ME/CFS with premature telomere attrition that is largely moderated by female subjects < 45 years old. Our results indicate that ME/CFS could be included in the list of conditions associated with accelerated aging. Further work is needed to evaluate the functional significance of accelerated aging in ME/CFS.

Source: Mangalathu S. RajeevanEmail author, Janna Murray, Lisa Oakley, Jin-Mann S. Lin and Elizabeth R. Unger. Association of chronic fatigue syndrome with premature telomere attrition. Journal of Translational Medicine201816:44© The Author(s) 2018 Received: 23 October 2017 Accepted: 16 February 2018 Published: 27 February 2018 https://doi.org/10.1186/s12967-018-1414-x (Full article)

Multi-Site Clinical Assessment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (MCAM): Design and Implementation of a Prospective/Retrospective Rolling Cohort Study

Abstract:

In the Multi-Site Clinical Assessment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (MCAM), we relied on expert clinician diagnoses to enroll patients from 7 specialty clinics in the United States in order to perform a systematic collection of data on measures of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS). Healthy persons and those with other illnesses that share some features with ME/CFS were enrolled in comparison groups. The major objectives were to:

1) use standardized questionnaires to measure illness domains of ME/CFS and to evaluate patient heterogeneity overall and between clinics;

2) describe the course of illness, identify the measures that best correlate with meaningful clinical differences, and assess the performances of questionnaires as patient/person-reported outcome measures;

3) describe prescribed medications, orders for laboratory and other tests, and management tools used by expert clinicians to care for persons with ME/CFS;

4) collect biospecimens for future hypothesis testing and for evaluation of morning cortisol profiles; and

5) identify measures that best distinguish persons with ME/CFS from those in the comparison groups and detect subgroups of persons with ME/CFS who may have different underlying causes.

Enrollment began in 2012 and is planned to continue in multiple stages through 2017. We present the MCAM methods in detail, along with an initial description of the 471 patients with ME/CFS who were enrolled in stage 1.

Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US

 

Source: Unger ER, Lin JS, Tian H, Natelson BH, Lange G, Vu D, Blate M, Klimas NG, Balbin EG, Bateman L, Allen A, Lapp CW, Springs W, Kogelnik AM, Phan CC, Danver J, Podell RN, Fitzpatrick T, Peterson DL, Gottschalk CG, Rajeevan MS; MCAM Study Group. Multi-Site Clinical Assessment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (MCAM): Design and Implementation of a Prospective/Retrospective Rolling Cohort Study. Am J Epidemiol. 2017 Mar 17:1-10. doi: 10.1093/aje/kwx029. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/28338983

 

Link between early menopause, chronic fatigue syndrome discovered

A newfound link between chronic fatigue syndrome (CFS) and early menopause was reported online today in Menopause, the journal of The North American Menopause Society (NAMS). This link, as well as links with other gynecologic problems and with pelvic pain, may help explain why CFS is two to four times more common in women than in men and is most prevalent in women in their 40s. Staying alert to these problems may also help healthcare providers take better care of women who may be at risk for CFS, say the authors of this population-based, case-control study.

Based on a long-term study of CFS and fatiguing illnesses in Georgia, this analysis from Centers for Disease Control scientists included 84 women with CFS and 73 healthy control women who completed detailed gynecologic history questionnaires. Striking differences emerged from the comparison between those groups.

The women with CFS were some 12 times more likely to have pelvic pain that wasn’t related to menstruation (such as pelvic floor dysfunction, interstitial cystitis/painful bladder syndrome or IC/PBS, and irritable bowel syndrome) than the control women. The women with CFS also reported excessive bleeding (74% vs 42%) much more often as well as significantly more bleeding between periods (49% vs 23%) and missing periods (38% vs 22%). In addition, they used hormones for purposes other than contraception (such as to treat irregular periods, menopausal symptoms or bone loss) much more often (57% vs 26%).

Also striking, most women with CFS–66%–had undergone at least one gynecologic surgery, compared with only 32% of controls, most commonly hysterectomy (55% versus 19%). Women with CFS underwent menopause early (at or before age 45) because of hysterectomy much more often (62% vs 33%). (Surgical menopause occurs immediately when both ovaries are removed at hysterectomy and often prematurely even when ovaries are preserved.) Bleeding as the reason for hysterectomy was significantly more common in the women with CFS. They also underwent natural menopause earlier, but the numbers were too small to show a significant difference.

Although CFS has previously been linked with pelvic pain and gynecologic conditions such as endometriosis, IC/PBS, polycystic ovaries, and menstrual abnormalities, this is the first study to show a link with early menopause. Sex hormone abnormalities or their early decrease or disappearance may underlie these links, and the authors called for more research to find out whether they do play a role in causing or perpetuating CFS in some women. But meanwhile, they emphasized, women’s healthcare providers need to stay alert for symptoms of CFS, such as sleep or memory problems, muscle and joint pain, and worse symptoms after exertion, developing in women who have these gynecologic or pelvic pain problems.

“CFS can take a tremendous toll on women’s lives at midlife and on our society and healthcare system. Being aware of the association of CFS and earlier menopause can help providers assist women in sorting out symptoms of CFS from symptoms of menopause,” says NAMS Executive Director Margery Gass, MD, NCMP. This paper also raises the chicken and egg question: Is early menopause the cause of later health problems or simply the result of earlier health problems not recognized as the cause of early menopause?

Journal Reference: Roumiana S. Boneva, Jin-Mann S. Lin, Elizabeth R. Unger. Early menopause and other gynecologic risk indicators for chronic fatigue syndrome in women. Menopause, 2015; 1 DOI: 10.1097/GME.0000000000000411

 

Source: The North American Menopause Society (NAMS). “Link between early menopause, chronic fatigue syndrome discovered.” ScienceDaily. ScienceDaily, 4 February 2015.  https://www.sciencedaily.com/releases/2015/02/150204075324.htm

 

Chronic fatigue syndrome patients had reduced activity in brain’s ‘reward center’

Chronic fatigue syndrome, a medical disorder characterized by extreme and ongoing fatigue with no other diagnosed cause, remains poorly understood despite decades of scientific study. Although researchers estimate that more than 1 million Americans are affected by this condition, the cause for chronic fatigue syndrome, a definitive way to diagnose it, and even its very existence remain in question. In a new study, researchers have found differing brain responses in people with this condition compared to healthy controls, suggesting an association between a biologic functional response and chronic fatigue syndrome.

The findings show that patients with chronic fatigue syndrome have decreased activation of an area of the brain known as the basal ganglia in response to reward. Additionally, the extent of this lowered activation was associated with each patient’s measured level of fatigue. The basal ganglia are at the base of the brain and are associated with a variety of functions, including motor activity and motivation. Diseases affecting basal ganglia are often associated with fatigue. These results shed more light on this mysterious condition, information that researchers hope may eventually lead to better treatments for chronic fatigue syndrome.

The study was conducted by Elizabeth R. Unger, James F. Jones, and Hao Tian of the Centers for Disease Control and Prevention (CDC), Andrew H. Miller and Daniel F. Drake of Emory University School of Medicine, and Giuseppe Pagnoni of the University of Modena and Reggio Emilia. An abstract of their study entitled, “Decreased Basal Ganglia Activation in Chronic Fatigue Syndrome Subjects is Associated with Increased Fatigue,” will be discussed at the meeting Experimental Biology 2012, being held April 21-25 at the San Diego Convention Center. The abstract is sponsored by the American Society for Investigative Pathology (ASIP), one of six scientific societies sponsoring the conference which last year attracted some 14,000 attendees.

More Fatigue, Less Activation

Dr. Unger says that she and her colleagues became curious about the role of the basal ganglia after previous studies by collaborators at Emory University showed that patients treated with interferon alpha, a common treatment for chronic hepatitis C and several other conditions, often experienced extreme fatigue. Further investigation into this phenomenon showed that basal ganglia activity decreased in patients who received this immune therapy. Since the fatigue induced by interferon alpha shares many characteristics with chronic fatigue syndrome, Unger and her colleagues decided to investigate whether the basal ganglia were also affected in this disorder.

The researchers recruited 18 patients with chronic fatigue syndrome, as well as 41 healthy volunteers with no symptoms of CFS. Each study participant underwent functional magnetic resonance imaging, a brain scan technique that measures activity in various parts of the brain by blood flow, while they played a simple card game meant to stimulate feelings of reward. The participants were each told that they’d win a small amount of money if they correctly guessed whether a preselected card was red or black. After making their choice, they were presented with the card while researchers measured blood flow to the basal ganglia during winning and losing hands.

The researchers showed that patients with chronic fatigue syndrome experienced significantly less change in basal ganglia blood flow between winning and losing than the healthy volunteers. When the researchers looked at scores for the Multidimensional Fatigue Inventory, a survey often used to document fatigue for chronic fatigue syndrome and various other conditions, they also found that the extent of a patient’s fatigue was tightly tied with the change in brain activity between winning and losing. Those with the most fatigue had the smallest change.

Results Suggest Role of Inflammation

Unger notes that the findings add to our understanding of biological factors that may play a role in chronic fatigue syndrome. “Many patients with chronic fatigue syndrome encounter a lot of skepticism about their illness,” she says. “They have difficulty getting their friends, colleagues, coworkers, and even some physicians to understand their illness. These results provide another clue into the biology of chronic fatigue syndrome.”

The study also suggests some areas of further research that could help scientists develop treatments for this condition in the future, she adds. Since the basal ganglia use the chemical dopamine as their major neurotransmitter, dopamine metabolism may play an important role in understanding and changing the course of this illness. Similarly, the difference in basal ganglia activation between the patients and healthy volunteers may be caused by inflammation, a factor now recognized as pivotal in a variety of conditions, ranging from heart disease to cancer.

Estimates from the CDC suggest that annual medical costs associated with chronic fatigue syndrome total about $14 billion in the United States. Annual losses to productivity because of lost work time range between $9 and $37 billion, with costs to individual households ranging between $8,000 and $20,000 per year.

 

Source: Federation of American Societies for Experimental Biology (FASEB). (2012, April 24). Chronic fatigue syndrome patients had reduced activity in brain’s ‘reward center’. ScienceDaily. Retrieved March 4, 2017 from https://www.sciencedaily.com/releases/2012/04/120424142109.htm

 

CDC Grand Rounds: Chronic Fatigue Syndrome – Advancing Research and Clinical Education

Abstract:

Chronic fatigue syndrome (CFS) is a complex and serious illness that is often misunderstood. Experts have noted that the terminology “chronic fatigue syndrome” can trivialize this illness and stigmatize persons who experience its symptoms (1). The name was coined by a group of clinicians convened by CDC in the late 1980s to develop a research case definition for the illness, which, at the time, was called chronic Epstein-Barr virus syndrome. The name CFS was suggested because of the characteristic persistent fatigue experienced by all those affected and the evidence that acute or reactivated Epstein-Barr virus infection was not associated with many cases (2).

However, the fatigue in this illness is striking and quite distinct from the common fatigue everyone experiences. A variety of other names have been used, including myalgic encephalomyelitis (ME), ME/CFS, chronic fatigue immune dysfunction, and most recently, systemic exertion intolerance disease (3). The lack of agreement about nomenclature need not be an impediment for advancing critically needed research and education. The term ME/CFS will be used in this article.

 

Source: Unger ER, Lin JS, Brimmer DJ, Lapp CW, Komaroff AL, Nath A, Laird S, Iskander J. CDC Grand Rounds: Chronic Fatigue Syndrome – Advancing Research and Clinical Education. MMWR Morb Mortal Wkly Rep. 2016 Dec 30;65(5051):1434-1438. doi: 10.15585/mmwr.mm655051a4. https://www.cdc.gov/mmwr/volumes/65/wr/mm655051a4.htm (Full article)

 

Methods of applying the 1994 case definition of chronic fatigue syndrome – impact on classification and observed illness characteristics

Abstract:

BACKGROUND: Multiple case definitions are in use to identify chronic fatigue syndrome (CFS). Even when using the same definition, methods used to apply definitional criteria may affect results. The Centers for Disease Control and Prevention (CDC) conducted two population-based studies estimating CFS prevalence using the 1994 case definition; one relied on direct questions for criteria of fatigue, functional impairment and symptoms (1997 Wichita; Method 1), and the other used subscale score thresholds of standardized questionnaires for criteria (2004 Georgia; Method 2). Compared to previous reports the 2004 CFS prevalence estimate was higher, raising questions about whether changes in the method of operationalizing affected this and illness characteristics.

METHODS: The follow-up of the Georgia cohort allowed direct comparison of both methods of applying the 1994 case definition. Of 1961 participants (53 % of eligible) who completed the detailed telephone interview, 919 (47 %) were eligible for and 751 (81 %) underwent clinical evaluation including medical/psychiatric evaluations. Data from the 499 individuals with complete data and without exclusionary conditions was available for this analysis.

RESULTS: A total of 86 participants were classified as CFS by one or both methods; 44 cases identified by both methods, 15 only identified by Method 1, and 27 only identified by Method 2 (Kappa 0.63; 95 % confidence interval [CI]: 0.53, 0.73 and concordance 91.59 %). The CFS group identified by both methods were more fatigued, had worse functioning, and more symptoms than those identified by only one method. Moderate to severe depression was noted in only one individual who was classified as CFS by both methods. When comparing the CFS groups identified by only one method, those only identified by Method 2 were either similar to or more severely affected in fatigue, function, and symptoms than those only identified by Method 1.

CONCLUSIONS: The two methods demonstrated substantial concordance. While Method 2 classified more participants as CFS, there was no indication that they were less severely ill or more depressed. The classification differences do not fully explain the prevalence increase noted in the 2004 Georgia study. Use of standardized instruments for the major CFS domains provides advantages for disease stratification and comparing CFS patients to other illnesses.

 

Source: Unger ER, Lin JM, Tian H, Gurbaxani BM, Boneva RS, Jones JF. Methods of applying the 1994 case definition of chronic fatigue syndrome – impact on classification and observed illness characteristics. Popul Health Metr. 2016 Mar 12;14:5. doi: 10.1186/s12963-016-0077-1. eCollection 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4788915/ (Full article)