The diagnostic work-up and outcomes of 'presumed' idiopathic acute pancreatitis: A post-hoc analysis of a multicentre observational cohort

INTRODUCTION

After standard diagnostic work-up, the aetiology of acute pancreatitis remains unknown in 16-27% of cases, a condition referred to as idiopathic acute pancreatitis (IAP). Determining the aetiology of pancreatitis is essential, as it may direct treatment in the acute phase and guides interventions to prevent recurrent pancreatitis.

METHODS

Between 2008 and 2015, patients with acute pancreatitis were registered prospectively in 19 Dutch hospitals. Patients who had a negative initial diagnostic work-up with regard to the underlying aetiology of their pancreatitis were labelled 'presumed' IAP. The aim of this study was to assess the use of diagnostic modalities and their yield to establish an aetiology in 'presumed' IAP, and to assess recurrence rates both with and without treatment.

RESULTS

Out of the 1632 registered patients, 191 patients had a first episode of 'presumed' IAP, of whom 176 (92%) underwent additional diagnostic testing: CT (n = 124, diagnostic yield 8%), EUS (n = 62, yield 35%), MRI/MRCP (n = 56, yield 33%), repeat ultrasound (n = 97, yield 21%), IgG4 (n = 54, yield 9%) and ERCP (n = 15, yield 47%). In 64 of 176 patients (36%) an aetiological diagnosis was established, mostly biliary (n = 39). In 13 out of 176 of patients (7%) a neoplasm was diagnosed. If additional diagnostic workup revealed an aetiology, the recurrence rate was lower in the treated patients than in the patients without a definite aetiology (15% versus 43%, p = 0.014).

CONCLUSION

Additional diagnostic testing revealed an aetiology in one-third of 'presumed' IAP patients. The aetiology found was mostly biliary, but occasionally neoplasms were found. Identification of an aetiology with subsequent treatment reduced the rate of recurrence.

Cost-effectiveness of same-admission versus interval cholecystectomy after mild gallstone pancreatitis in the PONCHO trial

Background

Same-admission cholecystectomy is indicated after gallstone pancreatitis to reduce the risk of recurrent disease or other gallstone-related complications, but its impact on overall costs is unclear. This study analysed the cost-effectiveness of same-admission versus interval cholecystectomy after mild gallstone pancreatitis.

Methods

In a multicentre RCT (Pancreatitis of biliary Origin: optimal timiNg of CHOlecystectomy; PONCHO) patients with mild gallstone pancreatitis were randomized before discharge to either cholecystectomy within 72 h (same-admission cholecystectomy) or cholecystectomy after 25–30 days (interval cholecystectomy). Healthcare use of all patients was recorded prospectively using clinical report forms. Unit costs of resources used were determined, and patients completed multiple Health and Labour Questionnaires to record pancreatitis-related absence from work. Cost-effectiveness analyses were performed from societal and healthcare perspectives, with the costs per readmission prevented as primary outcome with a time horizon of 6 months.

Results

All 264 trial participants were included in the present analysis, 128 randomized to same-admission cholecystectomy and 136 to interval cholecystectomy. Same-admission cholecystectomy reduced the risk of acute readmission for recurrent gallstone-related complications from 16·9 to 4·7 per cent (P = 0·002). Mean total costs from a societal perspective were €234 (95 per cent c.i. –1249 to 738) less per patient in the same-admission cholecystectomy group. Same-admission cholecystectomy was superior to interval cholecystectomy, with a societal incremental cost-effectiveness ratio of –€1918 to prevent one readmission for gallstone-related complications.

Conclusion

In mild biliary pancreatitis, same-admission cholecystectomy was more effective and less costly than interval cholecystectomy.

Systematic mechanism-orientated approach to chronic pancreatitis pain

Pain in chronic pancreatitis (CP) shows similarities with other visceral pain syndromes (i.e., inflammatory bowel disease and esophagitis), which should thus be managed in a similar fashion. Typical causes of CP pain include increased intrapancreatic pressure, pancreatic inflammation and pancreatic/extrapancreatic complications. Unfortunately, CP pain continues to be a major clinical challenge. It is recognized that ongoing pain may induce altered central pain processing, e.g., central sensitization or pro-nociceptive pain modulation. When this is present conventional pain treatment targeting the nociceptive focus, e.g., opioid analgesia or surgical/endoscopic intervention, often fails even if technically successful. If central nervous system pain processing is altered, specific treatment targeting these changes should be instituted (e.g., gabapentinoids, ketamine or tricyclic antidepressants). Suitable tools are now available to make altered central processing visible, including quantitative sensory testing, electroencephalograpy and (functional) magnetic resonance imaging. These techniques are potentially clinically useful diagnostic tools to analyze central pain processing and thus define optimum management approaches for pain in CP and other visceral pain syndromes. The present review proposes a systematic mechanism-orientated approach to pain management in CP based on a holistic view of the mechanisms involved. Future research should address the circumstances under which central nervous system pain processing changes in CP, and how this is influenced by ongoing nociceptive input and therapies. Thus we hope to predict which patients are at risk for developing chronic pain or not responding to therapy, leading to improved treatment of chronic pain in CP and other visceral pain disorders.

Altered central pain processing after pancreatic surgery for chronic pancreatitis

BACKGROUND

Chronic abdominal pain is common in chronic pancreatitis (CP) and may involve altered central pain processing. This study evaluated the relationship between pain processing and pain outcome after pancreatic duct decompression and/or pancreatic resection in patients with CP.

METHODS

Patients with CP underwent quantitative sensory testing. Pain processing was measured via electrical pain detection (ePDT) and electrical pain tolerance (ePTT) thresholds in dermatomes C5 and L4. Inhibitory descending pain control mechanisms were assessed using the conditioned pain modulation (CPM) paradigm. Healthy controls and patients with CP were compared, and patients with CP and a poor pain outcome (visual analogue scale (VAS) score greater than 30) were compared with those with a good pain outcome (VAS score 30 or less).

RESULTS

Forty-eight patients with CP had lower ePDT, ePTT and CPM responses compared with values in 15 healthy controls (P < 0·030). The sum of ePDT values was lower in patients with a poor pain outcome than in those with a good outcome (median 7·1 versus 11·2 mA; P = 0·008). There was a correlation with the VAS score and the sum of ePDT values (rs  = -0·45, P = 0·016) and ePTT values (rs  = -0·46, P = 0·011), and CPM response (rs  = -0·43, P = 0·006) in patients with CP.

CONCLUSION

After pain-relieving pancreatic surgery, patients with CP exhibit altered central pain processing compared with that in healthy controls. Poor pain outcomes are associated with more central sensitization and more pronociceptive descending pain modulation, and this should be considered when managing persistent pain after pain-relieving surgery for CP.