Applying case definition criteria to irritable bowel syndrome.

OBJECTIVE: The quality of documentation of signs and symptoms and validation of the diagnosis of irritable bowel syndrome (IBS) according to case definition criteria of Manning, Rome I and Rome II in an office setting has not been previously described. We sought to identify and validate cases of IBS based on the Manning, Rome I and Rome II diagnostic criteria in a rural practice setting.
SETTING: Marshfield Epidemiologic Study Area (MESA) Central consisting of 14 ZIP codes in central Wisconsin, USA.
METHODS: A retrospective cohort study involved 890 patients with the diagnostic codes 564.1 for irritable bowel syndrome and 306.4 spastic colon-psychogenic who had presented to the practice from 1993-2003. Duration, frequency, concordance and intensity of symptoms based on case definitions of IBS were abstracted from the medical records.
RESULTS: During the study period, 890 incident cases of IBS were identified. Only 404 met one or more of the three diagnostic criteria, 340 (84%) met only the Manning criteria, 35 (10%) met only Manning and Rome I criteria, 4 (1%) met both Manning and Rome II criteria, and 25 (6%) met Manning and Rome I and Rome II criteria. Age adjusted incidence rates per 100,000 person-years for validated IBS cases during the observational period were 87 to 170 by Manning (lower confidence interval [CI]: 57-127, upper CI: 116-213), 8 to 34 (lower CI: 0-14, upper CI: 16-53) for Rome I and 3 to 16 (lower CI: 0-3, upper CI: 8-28) for Rome II. Comparison of Rome I and Rome II showed moderate concordance (kappa statistic = 0.51; 95% CI: 0.39-0.64).
CONCLUSIONS: Only a small percentage of IBS cases with assigned diagnostic codes met case definition criteria for IBS. There were low concordance rates among the three diagnostic criteria applied.