Short-term Stability of Subtypes in IBS
Short-term Stability of Subtypes in IBS
Background In irritable bowel syndrome (IBS) subtyping is used in research and clinical practice. Knowledge of subtype stability is needed for proper design of trials and treatment strategies.
Aims To evaluate the stability of Rome III IBS subtypes over time and to determine the optimal time period for prospective, diary-based subtyping.
Methods Rome III IBS patients aged 18–70 years enrolled in two identical, randomised, placebo-controlled trials of probiotics, were included. No difference was found on stool pattern, thus patients were analysed as one group. Patients scored defaecations according to Bristol Stool Form Scale for 10 weeks. IBS subtypes were determined for all 1- and 2-week periods. Subtype distribution and stool pattern over time were determined. The proportions of patients having the same subtype all weeks (stable patients) or having a predominant subtype (same subtype ≥60% of time) were determined.
Results A total of 126 patients, mean age 46 ± 15 years, 72% women were included. Subtype distribution was similar over time with IBS with constipation, IBS with diarrhoea and IBS unsubtyped constituting one-third of the population each. Even though only 18–35% had the same subtype all weeks, the majority of patients had the same subtype for ≥60% of time (82–98%). Sixty-nine per cent had the same predominant and baseline subtypes. Two-week data increased the proportion of stable patients, of patients with a predominant subtype, and of patients who had similar baseline and predominant subtype.
Conclusions Most IBS patients change subtype over time. However, an underlying stool pattern stability was demonstrated in the majority of patients. To increase stability, we recommend 2-week data for IBS subtyping.
Irritable bowel syndrome (IBS) is a common condition affecting approximately 10% of the adult population in Western countries. Patients complain of abdominal pain or discomfort and an altered stool pattern. The currently accepted definition and subclassification of IBS is given by the Rome III criteria. According to these criteria, patients are grouped into different subtypes based on the predominant stool consistency. Stool consistency is recognised as a surrogate marker of intestinal transit time, and therefore different subtypes are thought to reflect different pathophysiological mechanisms. Four subtypes of IBS are defined: IBS with constipation (IBS-C), IBS with diarrhoea (IBS-D), IBS mixed type (IBS-M) and IBS unsubtyped (IBS-U). Alternating IBS (IBS-A) is defined as a subgroup of patients experiencing both periods of IBS-D and IBS-C over time. Prospective subtyping by self-report of stool pattern using the Bristol Stool Scale (BSS) is recommended by the Rome III committee. However, no recommendations exist on the optimal length of self reporting and no specification of the time period needed for defining IBS-A is given.
Initially subtyping was developed as a tool for selection and description of study populations in research, but now subtyping is also used in the clinical setting, as clinical guidelines use subtypes for recommending diagnostic tests and for recommending treatment based on the predominant stool pattern. For proper trial design and for proper choice of treatment and pattern of drug prescription it is important to acquire knowledge about IBS subtype stability over time. For trials recruiting patients with a specific subtype, it is important to be sure that the subtype actually reflects the stool pattern of the patient over time, and thus eligibility should not be dependent on which week the patient sought medical attention. In the clinical setting, patients with a stable stool pattern would possibly benefit from the same treatment over time. However, if patients do not have a stable stool pattern, it is important to revise treatment strategy, and use intermittent or on demand therapy.
This study aimed to evaluate the clinical course of prospective Rome III IBS subtypes over a short period of time and to address the question of whether or not an optimal time period for IBS subtyping exists.
Abstract and Introduction
Abstract
Background In irritable bowel syndrome (IBS) subtyping is used in research and clinical practice. Knowledge of subtype stability is needed for proper design of trials and treatment strategies.
Aims To evaluate the stability of Rome III IBS subtypes over time and to determine the optimal time period for prospective, diary-based subtyping.
Methods Rome III IBS patients aged 18–70 years enrolled in two identical, randomised, placebo-controlled trials of probiotics, were included. No difference was found on stool pattern, thus patients were analysed as one group. Patients scored defaecations according to Bristol Stool Form Scale for 10 weeks. IBS subtypes were determined for all 1- and 2-week periods. Subtype distribution and stool pattern over time were determined. The proportions of patients having the same subtype all weeks (stable patients) or having a predominant subtype (same subtype ≥60% of time) were determined.
Results A total of 126 patients, mean age 46 ± 15 years, 72% women were included. Subtype distribution was similar over time with IBS with constipation, IBS with diarrhoea and IBS unsubtyped constituting one-third of the population each. Even though only 18–35% had the same subtype all weeks, the majority of patients had the same subtype for ≥60% of time (82–98%). Sixty-nine per cent had the same predominant and baseline subtypes. Two-week data increased the proportion of stable patients, of patients with a predominant subtype, and of patients who had similar baseline and predominant subtype.
Conclusions Most IBS patients change subtype over time. However, an underlying stool pattern stability was demonstrated in the majority of patients. To increase stability, we recommend 2-week data for IBS subtyping.
Introduction
Irritable bowel syndrome (IBS) is a common condition affecting approximately 10% of the adult population in Western countries. Patients complain of abdominal pain or discomfort and an altered stool pattern. The currently accepted definition and subclassification of IBS is given by the Rome III criteria. According to these criteria, patients are grouped into different subtypes based on the predominant stool consistency. Stool consistency is recognised as a surrogate marker of intestinal transit time, and therefore different subtypes are thought to reflect different pathophysiological mechanisms. Four subtypes of IBS are defined: IBS with constipation (IBS-C), IBS with diarrhoea (IBS-D), IBS mixed type (IBS-M) and IBS unsubtyped (IBS-U). Alternating IBS (IBS-A) is defined as a subgroup of patients experiencing both periods of IBS-D and IBS-C over time. Prospective subtyping by self-report of stool pattern using the Bristol Stool Scale (BSS) is recommended by the Rome III committee. However, no recommendations exist on the optimal length of self reporting and no specification of the time period needed for defining IBS-A is given.
Initially subtyping was developed as a tool for selection and description of study populations in research, but now subtyping is also used in the clinical setting, as clinical guidelines use subtypes for recommending diagnostic tests and for recommending treatment based on the predominant stool pattern. For proper trial design and for proper choice of treatment and pattern of drug prescription it is important to acquire knowledge about IBS subtype stability over time. For trials recruiting patients with a specific subtype, it is important to be sure that the subtype actually reflects the stool pattern of the patient over time, and thus eligibility should not be dependent on which week the patient sought medical attention. In the clinical setting, patients with a stable stool pattern would possibly benefit from the same treatment over time. However, if patients do not have a stable stool pattern, it is important to revise treatment strategy, and use intermittent or on demand therapy.
This study aimed to evaluate the clinical course of prospective Rome III IBS subtypes over a short period of time and to address the question of whether or not an optimal time period for IBS subtyping exists.
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