Development of a novel CT-based index for predicting the number of extracorporeal shockwave lithotripsy (ESWL) sessions required for successful fragmentation of obstructing pancreatic duct stones.

BACKGROUND & AIM: Extracorporeal shock wave lithotripsy (ESWL) is used for the treatment of pancreatic duct stones (PDS) in patients with chronic pancreatitis (CP). We aimed to develop a CT based index to predict the required number of ESWL sessions for technical success. METHODS: We retrospectively evaluated patients with PDS secondary to CP who underwent ESWL. Technical success was defined as the complete fragmentation of stones to <3 mm. CT features including PDS size, number, location, and density in Hounsfield units (HU) were noted. We analyzed the relationship between PDS characteristics and the number of ESWL sessions required for technical success. A multiple linear regression model was used to combine size and density into the pancreatic duct stone (PDS) index that was translated into a web-based calculator. RESULTS: There were 206 subjects (mean age 38.6 ± 13.7 years, 59.2% male) who underwent ESWL. PDS size showed a moderate correlation with the number of ESWL sessions (r = 0.42, p < 0.01). PDS in the head required a fewer number of sessions in comparison to those in the body (1.4 ± 0.6 vs. 1.6 ± 0.7, p = 0.01). There was a strong correlation between PDS density and the number of ESWL sessions (r = 0.617, p-value <0.01). The PDS index {0.3793 + [0.0009755 x PDS density (HU)] + [0.02549 x PDS size (mm)]} could accurately predict the required number of ESWL sessions with an AUC of 0.872 (p < 0.01). CONCLUSION: The PDS index is a useful predictor of the number of ESWL sessions needed for technical success that can help in planning and patient counseling.

Pancreatic quantitative sensory testing to predict treatment response of endoscopic therapy or surgery for painful chronic pancreatitis with pancreatic duct obstruction: study protocol for an observational clinical trial.

INTRODUCTION: Treatment for abdominal pain in patients with chronic pancreatitis (CP) remains challenging in the setting of central nervous system sensitisation, a phenomenon of remodelling and neuronal hyperexcitability resulting from persistent pain stimuli. This is suspected to render affected individuals less likely to respond to conventional therapies. Endotherapy or surgical decompression is offered to patients with pancreatic duct obstruction. However, the response to treatment is unpredictable. Pancreatic quantitative sensory testing (P-QST), an investigative technique of standardised stimulations to test the pain system in CP, has been used for phenotyping patients into three mutually exclusive groups: no central sensitisation, segmental sensitisation (pancreatic viscerotome) and widespread hyperalgesia suggestive of supraspinal central sensitisation. We will test the predictive capability of the pretreatment P-QST phenotype to predict the likelihood of pain improvement following invasive treatment for painful CP. METHODS AND ANALYSIS: This observational clinical trial will enrol 150 patients from the University of Pittsburgh, Johns Hopkins and Indiana University. Participants will undergo pretreatment phenotyping with P-QST. Treatment will be pancreatic endotherapy or surgery for clearance of painful pancreatic duct obstruction. PRIMARY OUTCOME: average pain score over the preceding 7 days measured by Numeric Rating Scale at 6 months postintervention. Secondary outcomes will include changes in opioid use during follow-up, and patient-reported outcomes in pain and quality of life at 3, 6 and 12 months after the intervention. Exploratory outcomes will include creation of a model for individualised prediction of response to invasive treatment. ETHICS AND DISSEMINATION: The trial will evaluate the ability of P-QST to predict response to invasive treatment for painful CP and develop a predictive model for individualised prediction of treatment response for widespread use. This trial was approved by the University of Pittsburgh Institutional Review Board. Data and results will be reported and disseminated in conjunction with National Institutes of Health policies. TRIAL REGISTRATION NUMBER: NCT04996628.