Journal: Journal of General Internal Medicine. 2007 Jun;22(6):818-21.
Authors and affiliation: Schur EA, Afari N, Furberg H, Olarte M, Goldberg J, Sullivan PF, Buchwald D. Department of Medicine, University of Washington School of Medicine, Seattle, Washington, USA. [E-mail: firstname.lastname@example.org ]
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,
- Temporomandibular joint disorder,
- Major depression,
- Panic attacks,
- And posttraumatic stress disorder.
Objective: To examine interrelationships among these 9 conditions.
Design: Using data from a cross-sectional survey, we described associations and used latent class analysis to investigate complex interrelationships.
Participants: 3,982 twins from the University of Washington Twin Registry.
Measurements: 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.