AbstractAimThe aim was to determine whether specialist‐led habit training using Habit Training with Biofeedback (HTBF) is more effective than specialist‐led habit training alone (HT) for chronic constipation and whether outcomes of interventions are improved by stratification to HTBF or HT based on diagnosis (functional defaecation disorder vs. no functional defaecation disorder) by radio‐physiological investigations (INVEST).MethodThis was a parallel three‐arm randomized single‐blinded controlled trial, permitting two randomized comparisons: HTBF versus HT alone; INVEST‐ versus no‐INVEST‐guided intervention. The inclusion criteria were age 18–70 years; attending specialist hospitals in England; self‐reported constipation for >6 months; refractory to basic treatment. The main exclusions were secondary constipation and previous experience of the trial interventions. The primary outcome was the mean change in Patient Assessment of Constipation Quality of Life score at 6 months on intention to treat. The secondary outcomes were validated disease‐specific and psychological questionnaires and cost‐effectiveness (based on EQ‐5D‐5L).ResultsIn all, 182 patients were randomized 3:3:2 (target 384): HT n = 68; HTBF n = 68; INVEST‐guided treatment n = 46. All interventions had similar reductions (improvement) in the primary outcome at 6 months (approximately −0.8 points of a 4‐point scale) with no statistically significant difference between HT and HTBF (−0.03 points; 95% CI −0.33 to 0.27; P = 0.85) or INVEST versus no‐INVEST (0.22; −0.11 to 0.55; P = 0.19). Secondary outcomes showed a benefit for all interventions with no evidence of greater cost‐effectiveness of HTBF or INVEST compared with HT.ConclusionThe results of the study at 6 months were inconclusive. However, with the caveat of under‐recruitment and further attrition at 6 months, a simple, cheaper approach to intervention may be as clinically effective and more cost‐effective than more complex and invasive approaches.