Feeling bad in more ways than one: comorbidity patterns of medically unexplained and psychiatric conditions.
BACKGROUND
Considerable overlap in symptoms and disease comorbidity has been noted among medically unexplained and psychiatric conditions seen in the primary care setting, such as chronic fatigue syndrome, low back pain, irritable bowel syndrome, chronic tension headache, fibromyalgia, temporomandibular joint disorder, major depression, panic attacks, and posttraumatic stress disorder.


OBJECTIVE
To examine interrelationships among these 9 conditions.


METHODS
Using data from a cross-sectional survey, we described associations and used latent class analysis to investigate complex interrelationships.


METHODS
3,982 twins from the University of Washington Twin Registry.


METHODS
Twins self-reported a doctor's diagnosis of the conditions.


RESULTS
Comorbidity among these 9 conditions far exceeded chance expectations; 31 of 36 associations were significant. Latent class analysis yielded a 4-class solution. Class I (2% prevalence) had high frequencies of each of the 9 conditions. Class II (8% prevalence) had high proportions of multiple psychiatric diagnoses. Class III (17% prevalence) participants reported high proportions of depression, low back pain, and headache. Participants in class IV (73% prevalence) were generally healthy. Class I participants had the poorest markers of health status.


CONCLUSIONS
These results support theories suggesting that medically unexplained conditions share a common etiology. Understanding patterns of comorbidity can help clinicians care for challenging patients.
Schur
Ellen A
EA
Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA. ellschur@u.washington.edu
Afari
Niloofar
N
Furberg
Helena
H
Olarte
Megan
M
Goldberg
Jack
J
Sullivan
Patrick F
PF
Buchwald
Dedra
D
D000328:Adult; D002908:Chronic Disease / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology; D004200:Diseases in Twins; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D005356:Fibromyalgia / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000453:epidemiology; D017116:Low Back Pain / Q000175:diagnosis / Q000453:epidemiology; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology*; D008875:Middle Aged; D016584:Panic Disorder / Q000175:diagnosis / Q000453:epidemiology; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000453:epidemiology; D013705:Temporomandibular Joint Disorders / Q000175:diagnosis / Q000453:epidemiology; D018781:Tension-Type Headache / Q000175:diagnosis / Q000453:epidemiology