Stepped treatment of older adults on laxatives. The STOOL trial

Authors: Mihaylov S, Stark C, McColl E, Steen N, Vanoli A, Rubin G, Curless R, Barton R, Bond J

Journal: Health Technology Assessment Volume: 12 Issue: 13

Publication date: May 2008



Mihaylov S, Stark C, McColl E, Steen N, Vanoli A, Rubin G, et al.Stepped treatment of older adults on laxatives. The STOOL trial. Health Technol Assess 2008;12(13)

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To investigate the clinical effectiveness and cost-effectiveness of bulk-forming, stimulant and osmotic laxatives, and also of adding a second type of laxative agent in the treatment of patients whose constipation is not resolved by a single agent. Additionally, to define the meaning of constipation in older people from the perspective of GPs and older patients, and to investigate the use of prescribed and non-prescribed treatments for constipation in older people together with their adherence to prescribed treatments.


A multicentre pragmatic, factorial randomised controlled trial with economic evaluation and qualitative study using in-depth interviews and focus groups with older people, GPs and community nurses.


General practices in north-east England.


People aged 55 years or over with chronic constipation living in private households.


Six stepped-treatment strategies using three classes of laxatives: bulk, stimulant and osmotic preparations, singly and in combination.

Main outcome measures

The primary outcome was the constipation-specific Patient Assessment of Constipation--Symptoms/Patient Assessment of Constipation--Quality of Life. Secondary outcomes included EuroQoL 5 Dimensions, reported number of bowel movements per week, the presence/absence of the other Rome II criteria for constipation, adverse effects of treatment and relapse rates.


Recruitment to the trial was difficult and the trial was closed after recruiting 19 participants. GP participants provided patient-centred definitions that focused on the idea of a change from the norm as defined by the individual patient and 'textbook definitions' that focused on reduced frequency of defecation associated with a range of unpleasant sensations and other clinical symptoms. Nurses' definitions of constipation included both a patient-centred perspective and the description of particular symptoms associated with constipation. Older participants defined constipation in terms of frequency of bowel movements and changes in normal bowel routine. Older participants perceived constipation as follows: linked to specific diseases, medical conditions or health problems; caused by the consumption of specific medications or surgical procedures; caused by diet or eating habits; part of the ageing process; due to not going to the toilet when having the urge to defecate; hereditary; caused by stress or worry; and caused by environmental exposure. GP participants suggested that constipation is due to changes in diet and lifestyle; the physiology and degenerative processes of ageing; and the iatrogenic impact of opiate medications. Nurse participants identified that constipation is linked to decreased mobility, decreased food intake, decreased fluid intake and consumption of certain medications. For many older people their constipation emerged as a problem over a period of time; for some the 'condition' had existed for many years. Self-management of constipation had typically been their first response to the symptoms and continued once professional help had been sought. Older participants had a wide experience of different management strategies and treatments for constipation, and at the time of the study had firm preferences about the laxatives they would use. GP participants recognised the experience and use of laxatives of their patients. They exhibited strong personal preferences for different laxatives, often prescribing them in combination. Nurses were more likely than GPs to treat and prevent constipation using non-laxative measures; these included providing advice on appropriate dietary changes, increasing fluid intake and, if possible, encouraging exercise and mobility.


There is little shared understanding between patients and professionals about 'normal' bowel function with little consensus in general practice of the optimum management strategies for chronic constipation and the most effective strategies to use. Chronic constipation is seen as less important than other conditions prevalent in general practice (e.g. diabetes) because it is not an agreed management target within national frameworks. Consequently, practitioners had little interest in constipation as a research topic. Patient preferences and the absence of patient equipoise formed an enormous barrier to the recruitment of patients in the implementation of this trial. Studies are needed to investigate different methods of recruitment within the constraints of current ethical guidelines on 'opting in' and to identify barriers and facilitators to recruitment to complex trials in general. Patient preference trials and natural cohort observational studies are also needed to investigate the effectiveness or cost-effectiveness of different laxatives and treatment strategies in the management of chronic constipation.

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