The implications of the Rome III recommendations to change the irritable bowel syndrome (IBS) subtype criteria for stool pattern are unknown.
(1) Determine the level of agreement between Rome II and Rome III subtypes and (2) compare the behaviors of Rome II and Rome III subtypes over time.
Female patients (n=148) with Rome II defined IBS were prospectively tracked over 5 consecutive 3-month periods. At baseline, bowel habit reports on questionnaires were used to subclassify patients into Rome II and Rome III subtypes. Over the subsequent 15 months, bowel habit reports on diary cards were used to subclassify patients based on previously derived surrogate criteria into Rome II and Rome III IBS subtypes.
The level of agreement between Rome II and Rome III subtype assignments was quite high (86.5%; κ 0.79). The behavior of Rome II and Rome III subtypes over time was also similar in terms of subtype prevalence, subtype stability, and the proportion of subjects who met criteria for alternating irritable bowel syndrome.
Rome II and Rome III IBS subtypes are in high agreement and behave similarly over time. Therefore, studies that used Rome II subtype criteria and studies that will use Rome III criteria will define comparable populations.