TCBT versus TAU | WCBT versus TAU | |||||||

Estimated difference | 95% CI | Test (df) P value | Standardised difference† | Estimated difference | 95% CI | Test (df) P value | Standardised difference† | |

IBS-SSS | ||||||||

3 months | −69.2 | −88.7 to −49.7 | t=−7.0 (367) <0.001 | 0.73 | −53.0 | −74.9 to −31.1 | t=−4.7 (237) <0.001 | 0.56 |

6 months | −58.3 | −80.3 to −36.3 | t=−5.2 (295) <0.001 | 0.61 | −35.7 | −58.5 to −12.9 | t=−3.1 (257) 0.002 | 0.37 |

12 months‡ | −61.6 | −89.5 to −33.8 | t=−4.3 (1581) <0.001 | 0.65 | −35.2 | −57.8 to −12.6 | t=− 3.1 (275) 0.002 | 0.37 |

WSAS | ||||||||

3 months | −3.4 | −4.8 to −2.0 | t=−4.8 (355) <0.001 | 0.40 | −3.0 | −4.4 to −1.5 | t=−3.9 (288) <0.001 | 0.35 |

6 months | −2.7 | −4.2 to −1.2 | t=−3.6 (280) <0.001 | 0.32 | −2.5 | −4.0 to −1.0 | t=−3.3 (257) 0.001 | 0.30 |

12 months | −3.5 | −5.1 to −1.9 | t=−4.2 (268) <0.001 | 0.41 | −3.0 | −4.6 to −1.3 | t=−3.5 (258) 0.001 | 0.35 |

HADS | ||||||||

3 months | −2.1 | −3.2 to −0.9 | t=−3.6 (306) <0.001 | 0.30 | −2.5 | −3.7 to −1.3 | t=−4.0 (261) <0.001 | 0.36 |

6 months | −2.2 | −3.5 to −0.8 | t=−3.2 (227) 0.002 | 0.32 | −2.9 | −4.2 to −1.6 | t=−4.2 (230) <0.001 | 0.42 |

12 months | −2.8 | −4.1 to −1.5 | t=−4.3 (248) <0.001 | 0.41 | −2.3 | −3.7 to −1.0 | t=−3.4 (217) 0.001 | 0.34 |

Estimated OR | 95% CI | Test (df) P value | Estimated OR | 95% CI | Test (df) P value | |||

PEQ responders | ||||||||

3 months | 13.3 | 6.9 to 25.8 | t=7.7 (1347) <0.001 | 6.6 | 3.3 to 13.2 | t=5.4 (918) <0.001 | ||

6 months | 11.6 | 6.4 to 20.9 | t=8.1 (1134) <0.001 | 4.8 | 2.7 to 8.7 | t=5.2 (889) <0·001 | ||

12 months‡ | 9.3§ | 4.5 to 19.3 | t=6.0 (2369) <0.001 | 3.5 | 2.0 to 5.9 | t=4.5 (1079) <0.001 | ||

SGA responders | ||||||||

3 months | 10.2 | 5.8 to 18.1 | t=8.1 (1289) <0.001 | 6.4 | 3.6 to 11.3 | t=6.3 (824) <0.001 | ||

6 months | 6.2 | 3.7 to 10.4 | t=6.9 (1637) <0.001 | 5.0 | 2.8 to 8.8 | t=5.6 (630) <0.001 | ||

12 months‡ | 6.1¶ | 2.5 to 15.0 | t=3.9 (2957) <0.001 | 3.6 | 2.0 to 6.3 | t=4.4 (600) <0.001 |

*All inferences were derived by multiple imputation as described in the Methods section. Each model used 100 imputations.

†Differences were standardised by dividing by baseline SD for IBS-SS (95.5), WSAS (8.8) and HADS (6.9), respectively.

‡The 12-month model included therapist effects in the TCBT arm.

§The reported TCBT effect is a conditional effect (conditioned on therapist). The corresponding marginal ORs within site are 9.0 (Southampton GP Practices), 9.2 (Southampton Secondary Care), 9.3 (London GP Practices) and 9.3 (London Secondary Care).

¶The reported TCBT effect is a conditional effect (conditioned on therapist). The corresponding marginal ORs within site are 5.8 (Southampton GP Practices), 6.0 (Southampton Secondary Care), 5.9 (London GP Practices) and 5.9 (London Secondary Care).

HADS, Hospital Anxiety and Depression Scale; IBS-SSS, IBS Symptom Severity Score; PEQ, Patient Enablement Questionnaire; SGA, Subject’s Global Assessment of Relief; TAU, treatment as usual; TCBT, telephone-delivered CBT; WCBT, web-based CBT; WSAS, Work and Social Adjustment Scale.