Comorbidity in irritable bowel syndrome.
BACKGROUND
Comorbid nongastrointestinal symptoms account for two-thirds of excess health-care costs in irritable bowel syndrome (IBS).


OBJECTIVE
To determine whether IBS patients are at greater risk for specific comorbid disorders versus showing a general tendency to overreport symptoms; whether patients with inflammatory bowel disease (IBD) show patterns of comorbidity similar to IBS; whether comorbidity is explained by psychiatric disease; and whether excess comorbidity occurs in all IBS patients.


METHODS
All 3,153 patients in a health maintenance organization with a diagnosis of IBS in 1994-1995 were compared to 3,153 age- and gender-matched controls, and to 571 IBD patients. All diagnoses in a 4-yr period beginning 1 yr before their index visit were categorized as gastrointestinal, psychiatric, or nongastrointestinal somatic. Nongastrointestinal somatic diagnoses were further divided into symptom-based versus biological marker-based diagnoses.


RESULTS
Forty-eight of 51 symptom-based and 16 of 25 biomarker-based diagnoses were significantly more common in IBS versus controls. However, there were no unique associations. Bacterial, viral, and fungal infections and stroke were among diagnoses made more frequently in IBS. IBD patients were similar to controls. Greater somatic comorbidity was associated with concurrent psychiatric diagnosis. Only 16% of IBS patients had abnormally high numbers of comorbid diagnoses.


CONCLUSIONS
Comorbidity in IBS is due to a general amplification of symptom reporting and physician consultation rather than a few unique associations; this suggests biased symptom perception rather than shared pathophysiology. Comorbidity is influenced by, but is not explained by, psychiatric illness. Excess comorbidity is present in only a subset of IBS patients.
Whitehead
William E
WE
Center for Functional GI and Motility Disorders at the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7555, USA.
Palsson
Olafur S
OS
Levy
Rona R
RR
Feld
Andrew D
AD
Turner
Marsha
M
Von Korff
Michael
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D015897:Comorbidity; D005767:Gastrointestinal Diseases / Q000453:epidemiology; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000453:epidemiology*; D008875:Middle Aged; D019964:Mood Disorders / Q000453:epidemiology; D012307:Risk Factors; D013001:Somatoform Disorders / Q000453:epidemiology; D014861:Washington / Q000453:epidemiology
D015415:Biomarkers