Non-drug therapies for the management of chronic constipation in adults: the CapaCiTY research programme including three RCTs
Authors: Knowles Charles H , Booth Lesley , Brown Steve R , Cross Samantha , Eldridge Sandra , Emmett Christopher , Grossi Ugo , Jordan Mary , Lacy-Colson Jon , Mason James , McLaughlin John , Moss-Morris Rona , Norton Christine , Scott S Mark , Stevens Natasha , Taheri Shiva , Yiannakou Yan 
Published: November 2021

Background

Chronic constipation affects 1–2% of adults and significantly affects quality of life. Beyond the use of laxatives and other basic measures, there is uncertainty about management, including the value of specialist investigations, equipment-intensive therapies using biofeedback, transanal irrigation and surgery.

Objectives

(1) To determine whether or not standardised specialist-led habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback is more clinically effective than standardised specialist-led habit training alone, and whether or not outcomes of such specialist-led interventions are improved by stratification to habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback or habit training alone based on prior knowledge of anorectal and colonic pathophysiology using standardised radiophysiological investigations; (2) to compare the impact of transanal irrigation initiated with low-volume and high-volume systems on patient disease-specific quality of life; and (3) to determine the clinical efficacy of laparoscopic ventral mesh rectopexy compared with controls at short-term follow-up.

Design

The Chronic Constipation Treatment Pathway (CapaCiTY) research programme was a programme of national recruitment with a standardised methodological framework (i.e. eligibility, baseline phenotyping and standardised outcomes) for three randomised trials: a parallel three-group trial, permitting two randomised comparisons (CapaCiTY trial 1), a parallel two-group trial (CapaCiTY trial 2) and a stepped-wedge (individual-level) three-group trial (CapaCiTY trial 3).

Setting

Specialist hospital centres across England, with a mix of urban and rural referral bases.

Participants

The main inclusion criteria were as follows: age 18–70 years, participant self-reported problematic constipation, symptom onset > 6 months before recruitment, symptoms meeting the American College of Gastroenterology’s constipation definition and constipation that failed treatment to a minimum basic standard. The main exclusion criteria were secondary constipation and previous experience of study interventions.

Interventions

CapaCiTY trial 1: group 1 – standardised specialist-led habit training alone (n = 68); group 2 – standardised specialist-led habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback (n = 68); and group 3 – standardised radiophysiological investigations-guided treatment (n = 46) (allocation ratio 3 : 3 : 2, respectively). CapaCiTY trial 2: transanal irrigation initiated with low-volume (group 1,n = 30) or high-volume (group 2,n = 35) systems (allocation ratio 1 : 1). CapaCiTY trial 3: laparoscopic ventral mesh rectopexy performed immediately (n = 9) and after 12 weeks’ (n = 10) and after 24 weeks’ (n = 9) waiting time (allocation ratio 1 : 1 : 1, respectively).

Main outcome measures

The main outcome measures were standardised outcomes for all three trials. The primary clinical outcome was mean change in Patient Assessment of Constipation Quality of Life score at the 6-month, 3-month or 24-week follow-up. The secondary clinical outcomes were a range of validated disease-specific and psychological scoring instrument scores. For cost-effectiveness, quality-adjusted life-year estimates were determined from individual participant-level cost data and EuroQol-5 Dimensions, five-level version, data. Participant experience was investigated through interviews and qualitative analysis.

Results

A total of 275 participants were recruited. Baseline phenotyping demonstrated high levels of symptom burden and psychological morbidity. CapaCiTY trial 1: all interventions (standardised specialist-led habit training alone, standardised specialist-led habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback and standardised radiophysiological investigations-guided habit training alone or habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback) led to similar reductions in the Patient Assessment of Constipation Quality of Life score (approximately –0.8 points), with no statistically significant difference between habit training alone and habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback (–0.03 points, 95% confidence interval –0.33 to 0.27 points;p = 0.8445) or between standardised radiophysiological investigations and no standardised radiophysiological investigations (0.22 points, 95% confidence interval –0.11 to 0.55 points;p = 0.1871). Secondary outcomes reflected similar levels of benefit for all interventions. There was no evidence of greater cost-effectiveness of habit training plus pelvic floor retraining using computer-assisted direct visual biofeedback or stratification by standardised radiophysiological investigations compared with habit training alone (with the probability that habit training alone is cost-effective at a willingness-to-pay threshold of £30,000 per quality-adjusted life-year gain;p = 0.83). Participants reported mixed experiences and similar satisfaction in all groups in the qualitative interviews. CapaCiTY trial 2: at 3 months, there was a modest reduction in the Patient Assessment of Constipation Quality of Life score, from a mean of 2.4 to 2.2 points (i.e. a reduction of 0.2 points), in the low-volume transanal irrigation group compared with a larger mean reduction of 0.6 points in the high-volume transanal irrigation group (difference –0.37 points, 95% confidence interval –0.89 to 0.15 points). The majority of participants preferred high-volume transanal irrigation, with substantial crossover to high-volume transanal irrigation during follow-up. Compared with low-volume transanal irrigation, high-volume transanal irrigation had similar costs (median difference –£8, 95% confidence interval –£240 to £221) and resulted in significantly higher quality of life (0.093 quality-adjusted life-years, 95% confidence interval 0.016 to 0.175 quality-adjusted life-years). CapaCiTY trial 3: laparoscopic ventral mesh rectopexy resulted in a substantial short-term mean reduction in the Patient Assessment of Constipation Quality of Life score (–1.09 points, 95% confidence interval –1.76 to –0.41 points) and beneficial changes in all other outcomes; however, significant increases in cost (£5012, 95% confidence interval £4446 to £5322) resulted in only modest increases in quality of life (0.043 quality-adjusted life-years, 95% confidence interval –0.005 to 0.093 quality-adjusted life-years), with an incremental cost-effectiveness ratio of £115,512 per quality-adjusted life-year.

Conclusions

Excluding poor recruitment and underpowering of clinical effectiveness analyses, several themes emerge: (1) all interventions studied have beneficial effects on symptoms and disease-specific quality of life in the short term; (2) a simpler, cheaper approach to nurse-led behavioural interventions appears to be at least as clinically effective as and more cost-effective than more complex and invasive approaches (including prior investigation); (3) high-volume transanal irrigation is preferred by participants and has better clinical effectiveness than low-volume transanal irrigation systems; and (4) laparoscopic ventral mesh rectopexy in highly selected participants confers a very significant short-term reduction in symptoms, with low levels of harm but little effect on general quality of life.

Limitations

All three trials significantly under-recruited [CapaCiTY trial 1,n = 182 (target 394); CapaCiTY trial 2,n = 65 (target 300); and CapaCiTY trial 3,n = 28 (target 114)]. The numbers analysed were further limited by loss before primary outcome.

Trial registration

Current Controlled Trials ISRCTN11791740, ISRCTN11093872 and ISRCTN11747152.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 9, No. 14. See the NIHR Journals Library website for further project information.