LAUSR

Introduction Centrally mediated disorders (chronic abdominal pain syndrome (CAPS) and narcotic bowel syndrome (NBS)) have been redefined by Rome IV1. We aimed to compare Rome IV and neuropathic pain (NP)2 criteria performance in a disease specific cohort of chronic continuous or nearly continuous abdominal pain (CCAP). Method Patients with unexplained CCAP in a tertiary neurogastroenterology clinic (2009–2016) were initially assessed for ‘clinical’ diagnoses of NP or NBS based on history and presence of cutaneous abdominal allodynia. Other primary functional diagnoses and anterior cutaneous nerve entrapment were excluded. Two independent investigators retrospectively reviewed case notes for Rome IV centrally mediated disorders and NP criteria. Results Of 104 referrals (mean age 40 years, 86% female) with CCAP, 92/104 (88%) were initially diagnosed with NP and 12/104, 12% with NBS. NBS compared to NP had greater unresolved or worsened pain despite escalating narcotic doses (p=0.0002), “soar and crash” (p=0.03) and progressive pain (p<0.0001). Retrospective analysis revealed only 51/104 (49%) met Rome IV criteria of a centrally mediated disorder. In particular, only 42/92 initially diagnosed with NP met CAPS criteria and only 9/12 diagnosed NBS patients met NBS criteria. The main reason (47/50, 94%) for not meeting Rome IV CAPS criteria in non-NBS patients was frequent CCAP exacerbation by ‘physiological events’ (post-prandially (n=37), on defecation (n=8), preceding defecation (n=5) and menstruation (n=2) with some overlap). By contrast, most patients retrospectively satisfied several NP criteria including 101/104, 97% reporting ‘spontaneous’ pain and 103/104, 99% ‘difficult to manage’. Cutaneous abdominal allodynia was present in 83/104, 80%. NP criteria for ‘shooting pain’ (p=0.04) and cutaneous allodynia (p=0.0002) were associated with opiate use. Pain relieved by applying topical heat and erythema ab igne were associated with opiate non-use (p=0.03). Conclusion This first evaluation of Rome IV CAPS and NBS criteria in a disease-specific cohort suggests considerable overlap with NP. Rome IV had low sensitivity compared with NP, due to frequent exacerbation of CCAP by physiological events. This may reflect visceral allodynia and should not preclude a centrally mediated diagnosis. Cutaneous abdominal allodynia is associated with opiate use and may be a marker for opioid-induced hyperalgesia in pre-existing NP. References . Keefer, et al. Gastro2016. . Searle, et al. Br J Anaes2012. Disclosure of Interest None Declared