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.