Introduction The proportion of patients who take opioid based analgesics and cannabis has not been studied in a large cohort of patients with CVS in the UK. It is also unclear whether the efficacy of prophylactic TCA is impacted by ongoing opioid or cannabis use. Aims: (A) to study the burden of opioid and cannabis use in patients with CVS, (b) to study the clinical response to prophylactic TCA and whether this was augmented by opioid/cannabis intake.

Methods Clinical characteristics and healthcare outcomes of patients diagnosed with ROME IV CVS in a single neurogastroenterology clinic between January 2016 to December 2023 were retrospectively collected. A standardised clinic template was used to collect data relating to age, sex, gastrointestinal symptoms, medication usage, and patient-reported response to TCA. Patients commenced 10mg TCA for 60 days which was up titrated by 10 mg at each routine outpatient consultation (unless poorly tolerated) until clinical remission was achieved or the maxmum dose (50 mg daily) was prescribed. Clinical remission was defined as the absence of stereotypical episodes of vomiting for at least 6 months prior to the last clinic consultation.

Results 95 patients (male 21%, mean age 30.8±11.8 years) were identified and 84 (88%) were seen on at least two or more occasions with a median duration of follow-up of 22 (IQR: 5, 39) months. The treatment outcomes for all patients treated with TCA are outlined in table 1. At the initial consultation, 35 (37%) and 16 (17%) patients took prescribed opioid analgesics and cannabis, respectively. All were provided with drug cessation advice and were prescribed a TCA: only 12/35 (34%) and 11/16 (69%) of patients adhered to drug cessation advice. On follow-up, 100% of patients who adhered to recommendations to stop opioids and cannabis responded to TCA whilst 0% of patients who continued to take opioids/cannabis responded to TCA. Illicit drugs were found at urine drug screening in 5 patients who failed to respond to TCA (cocaine n=2 and heroin n=3).

Conclusion This is the first UK study reporting the impact of opioid usage and illicit drugs in patients with CVS. TCAs are useful in treating CVS patients providing they do not consume prescribed opioids or illicit drugs.