Letter: Assessing the Durability of Treatment Effects: Long-Term Outcomes of ESWL and ERCP for Pancreatic Duct Stones in Chronic Pancreatitis—Authors' Reply

We would like to thank Dr. Tang et al. for their insights and comments [1] on our study entitled ‘Long-term Clinical Outcomes of Extracorporeal Shockwave Lithotripsy and Endoscopic Retrograde Cholangiopancreatography for Pancreatic Duct Stone Treatment in Patients with Chronic Pancreatitis’ [2] which reported the efficacies of extracorporeal shockwave lithotripsy for pancreatic stones (P-ESWL) and endoscopic retrograde cholangiopancreatography (ERCP) for painful chronic pancreatitis (CP). As we have stated in the limitation part that pain relief and pain type conversion in patients with CP after P-ESWL and ERCP treatment may be influenced by many confounding factors, several factors like history of pancreatic surgery, presence of pancreatic pseudocysts, may also influence the treatment efficacy. The proportion of patients underwent pancreatic surgery and patients with pancreatic pseudocysts in our study exhibited in table 1 were low which could cause little effects to our study's conclusion [2]. Patients diagnosed with pancreatic cancer within 2 years after diagnosis of ‘CP’ has been excluded from the current study as shown in figure S1; because the initial diagnosis of those patients were misdiagnosed, which ensured the purity of the study population [2, 3]. Patients may develop pancreatic cancer during the long-term disease course of CP which is an important clinical event for CP [4]. Patients with newly diagnosed pancreatic cancer may present distinct pain patterns. However, the results could hardly be affected due to the quite low ratio of these patients. Patients with significant ascites, multiple strictures (chain of lake appearance) and suspicious pancreatic head mass were not eligible for P-ESWL treatment and thus were not included in the study [5].

As it was exhibited in the Methods part, ERCP is performed according to the guideline as much as possible [6]. In most cases, two ERCP procedures after P-ESWL would be performed in each patient in our study. The first ERCP after P-ESWL is for removing the fragmented stones and placing stents if necessary. The second ERCP is for removing pancreatic stents 1 year later. In very rare cases, more ERCPs are performed to solve some difficult problems, like stent detachment and stent displacement. Totally 1929 out of 2071 patients underwent ERCP after P-ESWL treatment. Technique success which was defined as success in stone extraction in the main pancreatic duct was achieved in 86.5% patients in the first ERCP after P-ESWL. For those with failed stone extraction, further surgery rather than repetitive ERCP would be preferred when considering the likelihood of procedural success. Hence, multiple ERCPs were not common in our study. The number of P-ESWLs would cause little influence on the treatment efficacy as the P-ESWL procedures aimed at fragmenting pancreatic stones into smaller pieces < 3 mm. P-ESWL would stop once the goal was achieved. The complication risk of P-ESWL was not a major focus of the current study and it was analysed in detail in the other study [7].

Ultimately, the current study has included adequate potential factors and provided relatively robust evidence for the treatment efficacy of P-ESWL and ERCP for patients with CP.

Yu Liu: conceptualization, writing – original draft, writing – review and editing. Liang-Hao Hu: conceptualization, writing – original draft, writing – review and editing.

The authors declare no conflicts of interest.

This article is linked to Liu et al papers. To view these articles, visit https://doi.org/10.1111/apt.18224 and https://doi.org/10.1111/apt.18321.