ORIGINAL INVESTIGATION Overlapping Conditions Among Patients With Chronic Fatigue Syndrome, Fibromyalgia, and Temporomandibular Disorder Leslie A. Aaron, PhD, MPH; Mary M. Burke, MD; Dedra Buchwald, MD Background: Patients with chronic fatigue syndrome diagnoses of the 10 clinical conditions beyond their re- (CFS), fibromyalgia (FM), and temporomandibular dis- ferring diagnosis of CFS, FM, or TMD. In contrast, pa- order (TMD) share many clinical illness features such as tients were more likely than controls to meet lifetime myalgia, fatigue, sleep disturbances, and impairment in abil- symptom and diagnostic criteria for many of the condi- ity to perform activities of daily living as a consequence tions, including CFS, FM, irritable bowel syndrome, mul- of these symptoms. A growing literature suggests that a tiple chemical sensitivities, and headache. Lifetime rates variety of comorbid illnesses also may commonly coexist of irritable bowel syndrome were particularly striking in in these patients, including irritable bowel syndrome, the patient groups (CFS, 92%; FM, 77%; TMD, 64%) com- chronic tension-type headache, and interstitial cystitis. pared with controls (18%) (P,.001). Individual symp- tom analysis revealed that patients with CFS, FM, and Objective: To describe the frequency of 10 clinical con- TMD share common symptoms, including generalized ditions among patients with CFS, FM, and TMD com- pain sensitivity, sleep and concentration difficulties, bowel pared with healthy controls with respect to past diag- complaints, and headache. However, several symptoms noses, degree to which they manifested symptoms for each also distinguished the patient groups. condition as determined by expert-based criteria, and pub- lished diagnostic criteria. Conclusions: This study provides preliminary evidence that patients with CFS, FM, and TMD share key symptoms. Methods: Patients diagnosed as having CFS, FM, and TMD It also is apparent that other localized and systemic con- by their physicians were recruited from hospital-based clin- ditions may frequently co-occur with CFS, FM, and TMD. ics. Healthy control subjects from a dermatology clinic were Future research that seeks to identify the temporal rela- enrolled as a comparison group. All subjects completed a tionships and other pathophysiologic mechanism(s) link- 138-item symptom checklist and underwent a brief physi- ing CFS, FM, and TMD will likely advance our understand- cal examination performed by the project physicians. ing and treatment of these chronic, recurrent conditions. Results: With little exception, patients reported few past Arch Intern Med. 2000;160:221-227 BSERVANT physiciansover cystitis, suggest a possible common alter- the years have described ation in central processing mechanisms.1 numerous clinical condi- A small literature on relationships be- tions that share features tween CFS, FM, and TMD supports the such as fatigue, pain and contention that, despite a multiplicity of Oother symptoms in the absence of objective diagnostic labels, these syndromes may findings, disability out of proportion to represent “overlapping” conditions. In this physical findings, and an apparent associa- regard, it has been estimated that be- tion with “stress” and psychosocial factors. tween 20% and 70% of patients with FM These include illnesses such as chronic meet criteria for CFS and, conversely, 35% fatigue syndrome (CFS), fibromyalgia to 70% of those with CFS also have FM.2-5 (FM), and temporomandibular disorder Studies investigating the relationship be- (TMD), as well as irritable bowel syndrome tween FM and TMD have demonstrated (IBS), interstitial cystitis, multiple chemi- that 18% of patients with TMD meet FM From the Department of cal sensitivities, chronic tension-type criteria, and 75% of patients with FM sat- Medicine, Division of General headaches, post–concussive syndrome, isfy the Research Diagnostic Criteria for Internal Medicine, University of chronic pelvic pain, and chronic low back TMD (myofascial type).6,7 Other data, Washington, Seattle (Drs Aaron and Buchwald), and the pain. Although often labeled “psychoso- though limited, suggest that patients with Department of Internal matic” or “functional” disorders, similari- CFS, FM, and TMD commonly report Medicine, University of ties in clinical manifestations among these symptoms that characterize other over- Kentucky, Lexington conditions, such as increased pain sensi- lapping disorders. However, only re- (Dr Burke). tivity in patients with FM and interstitial cently have the similarities of CFS, FM, and ARCH INTERN MED/ VOL 160, JAN 24, 2000 WWW.ARCHINTERNMED.COM 221 ©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 SUBJECTS AND METHODS chronic tension-type headache, IBS, interstitial cystitis, post–concussive syndrome, multiple chemical sensitivi- ties, chronic pelvic pain, and chronic low back pain. For SUBJECTS AND SETTING the self-reported overlapping conditions, subjects were asked “Have you ever been told by a health care provider The sample consisted of 25 patients with CFS, 22 patients that you have...”.Symptoms for the 10 conditions of with FM, 25 patients with TMD, and 22 healthy control interest were derived from several sources. For CFS, subjects. All subjects were new or established patients FM, IBS, and chronic tension-type headache we used recruited from hospital-based clinics affiliated with the published criteria.12,15-17 For TMD, interstitial cystitis, University of Washington and Pacific Medical Center in post–concussive syndrome, multiple chemical sensitivi- Seattle between January 1993 and September 1994. ties, chronic pelvic pain, and chronic low back pain, char- Patients with CFS were attending the Chronic Fatigue acteristic symptoms were derived from 2 additional Clinic, a tertiary care referral practice. Patients with FM sources: (1) consultations with university faculty who and TMD were seeking care at an academic rheumatology had established expertise in the diagnosis and treatment and oral medicine clinic, respectively. Control subjects of a given disorder (“experts”), and (2) searches of the ex- included individuals from 2 dermatology clinics who tant literature for characteristic symptoms. Thus, the were being evaluated for conditions other than CFS, FM, final items compiled for each disorder in the symptom or TMD. Control subjects were healthy (ie, without checklist included both criteria-based symptoms and major, chronic medical problems) and were typically well-recognized features used in clinical practice in the being seen for minor, nonsystemic, skin conditions (eg, diagnosis of the study conditions. Prior to the administra- warts). tion to subjects, the questions contained in the checklist In each of the clinics, a single, designated participat- for each individual disorder were approved by the appro- ing physician was asked to approach patients diagnosed priate expert. as having CFS, FM, or TMD. In the case of the control To score the symptom checklist, the total number subjects, the physician selected only patients who were of symptoms endorsed for each syndrome were summed healthy with the exception of their dermatologic condi- to obtain a subject’s score for the relevant clinical condi- tion. Treating physicians were well-versed in the applica- tion. This score was intended to approximate the degree tion of published research criteria11-13 for the 3 conditions to which subjects reported characteristics of a particular under study. Patients with CFS were diagnosed using the syndrome as determined by our experts. All reported 1988 Centers for Disease Control case definition11 and a diagnoses and symptoms represent lifetime occurrence recommended modification that does not exclude those rates. with specific psychiatric diagnoses.14 Patients with FM Finally, we were interested in common and distin- were classified according to the American College of guishing symptoms among the patient groups. “Common Rheumatology criteria for FM.12 The diagnosis of TMD symptoms” were those for which there was both a clinical was directed by the Research Diagnostic Criteria.13 This (defined as .25% difference in frequency) and a statisti- study was approved by the University of Washington Hu- cally significant (P#.01) difference between the CFS, FM, man Subjects Office and all subjects provided written, in- TMD patient groups and controls. To be designated as a formed consent upon enrollment. “distinguishing symptom,” the symptom must have dif- ferentiated the specified group(s) of interest from the oth- DATA COLLECTION er(s) by these same criteria. For example, a distinguishing symptom of TMD was considered to differentiate patients Subjects were approached to participate in the study dur- with TMD from those with CFS, those with FM, and con- ing routine clinic visits or by mailed letters to patients trols if a greater than 25% difference in frequency and deemed eligible by the designated clinic physician. Infor- P#.01 statistical difference existed between the TMD mation was gathered from interested subjects at their con- group and each of the other groups’ mean scores on that venience, either following a regularly scheduled appoint- symptom. ment or during a separate study appointment scheduled at another time. Patients who were unable to complete the STATISTICAL ANALYSES lengthy questionnaire at the time of the study evaluation were asked to complete it at home and mail it to the in- We used x2 analyses to compare the