The NIS database is directed to determine health care utilization, access, charges, quality and outcomes[21
]. NSQIP focuses on perioperative complications, with a mandate to determine the quality of surgical care[22
] and SEER focuses on the incidence, prevalence and survival of cancer[23
]. Taking into consideration the goal of each database, we amalgamated the available information from these respected datasets to obtain an integrated and broad nationwide analysis of distal pancreas resection. Specifically we found NIS useful to assess laparoscopy utilization and comorbidities, comparison of costs and analysis by hospital type (teaching and non-teaching). On the other hand, the NSQIP database is more appropriate for detailed analysis of perioperative complications and patient risk factors. Oncological metrics and outcomes are best assessed by the SEER database. All of these have limitations, but we believe that the nationwide databases are complementary to each other and it is helpful to present an analysis of them together. The limiting factor we encounter in both NIS and NSQIP is that procedures are grouped in broad categories, limiting the ability to distinguish the role of laparoscopy in each procedure. Though using the current coding system allowed for a general procedure analysis, an improvement in coding system that further categorizes procedures will facilitate a more detailed analysis.
Overall, we found that in patients where laparoscopy was utilized, the median length of stay was shorter. This reinforces the findings of single center studies[8,12,15,24
]. Recently, Venkat et al[9
] in a meta-analysis reported that patients that underwent a laparoscopic distal pancreatectomy had not just a lower blood loss and hospital length of stay, but also had fewer complications and surgical site infections. Importantly, no difference was found in operative time, margin positivity, incidence of postoperative pancreatic fistula or mortality. Additionally, we found that utilization of laparoscopy reduced overall expenses; this finding is likely secondary to the shorter length of stay and lower complication rate.
Other recent reports have confirmed the advantages of laparoscopic distal pancreatectomy over open approach, in terms of lower intraoperative blood loss, pain and analgesic requirements, earlier return of bowel function, shorter recovery and hospital stay[9,10,14,25,26
]. Therefore, the subset of patients with medical comorbidities could potentially benefit more than healthier patients, but we did not find that patient morbidity was associated with use of minimally invasive surgery.
Despite the known and reported benefits, overall laparoscopy was utilized in 15% (NIS) and 27% (NSQIP) of the distal pancreas resection cases. This represents all patients that had laparoscopy performed for diagnosis, staging, resection or a combination of these procedures. The rate of utilization of laparoscopy has remained stable over most of the past decade, although we could not determine in each case the specific technique of laparoscopy used. The finding of no increase in utilization of laparoscopy could be explained by the low number of pancreas surgeons that perform laparoscopic pancreatic resection. Also, another potential explanation for this stable rate could be that more laparoscopic resections and fewer diagnostic staging procedures are being performed over the study course, but these changes could not be detected by our analysis.
In our analysis, we showed that laparoscopy was utilized more frequently in malignant lesions, which could be due to utilization of laparoscopy for diagnosis and/or staging purposes. Interestingly, we did not find that laparoscopy was utilized and performed more frequently in teaching or high volume hospitals, though we expected that teaching hospitals and specialized medical centers would perform more MIS resection cases. It is not surprising that NSQIP hospitals have a higher rate of laparoscopy utilization than NIS hospitals, because NSQIP hospitals have volunteered for the program in an effort to improve quality. But it would not be appropriate to further compare data across different databases.
No consensus exists for or against the use of laparoscopic approach for distal pancreatectomy in malignant lesions, though recent publications support this approach in selected patients[7
]. It has also been reported that after laparoscopic distal pancreatectomy in patients with invasion, a resection to negative margins and adequate lymph node harvest can be accomplished[15
]. We also found that postoperative complications were more common after resection of malignant lesions, but even in malignant lesions use of laparoscopy was associated with a decrease in complications. The reported laparoscopic distal pancreatectomy morbidity ranges from 20% to 47% and the reported mortality rate ranges from 3% to 5%[14,27,28
]. Our study shows that nationwide mortality is at or below the benchmark reported data. The most common reported complications after laparoscopic distal pancreatectomy are pancreatic fistula, intra-abdominal abscesses, wound infection, sepsis, malabsortion, electrolyte disturbance and hemorrhage[14,27,28
]. The rate of intra-abdominal infection we report (9%) is also at or below reported benchmarks. This may reflect inaccuracy of coding.
Regarding oncological outcomes, no increase was seen in the number of lymph nodes harvested and lymph node ratio in N1 disease. More importantly the 1-year and 2-year survival did not increase during the course of this study.
The oncological surrogate markers associated with survival in pancreas cancer such as tumor size, tumor differentiation, surgical margins, lymph node status and lymph node ratio have been well documented[8,10,11,15,29
]. We speculate that surgeons might opt for open operation to enable a more radical oncologic resection. This however, does not appear to be the case, as survival and oncologic surrogate markers were unchanged over the course of the study. We believe that published data support using MIS to perform a more radical oncologic resection, but these data show this is not a common practice across the country[8,15,16,30
Multiple reports support centralization of oncological pancreas procedures towards high-volume hospitals, and as a result of this, a decrease in mortality has also been reported[17-20
]. Stitzenberg et al[18
] analyzed the NIS database to assess cancer surgery centralization for pancreas, esophagus and colon cancer. Interestingly, during the course of the study there was a decrease in total number of hospitals performing pancreas procedures, but a statistical significant increase in the number of high-volume hospitals and a decrease in low-volume hospitals performing pancreatectomy procedures. All the high-volume centers were teaching hospitals. A total of 8.3% patients with a diagnosis of pancreas malignancy were admitted through an emergency room, and were more likely to have surgery done in a low-volume hospital.
Forces opposing the trend for centralization include the technological advances in imaging, resulting in diagnosis of pancreas lesions at earlier stages. Smaller lesions could potentially be managed in a non-specialized hospital, and only complicated cases referred to specialized hospitals. On the other hand, recent reports and guidelines support the use of endoscopic ultrasound with guided fine-needle aspiration for diagnosis and staging of body and tail pancreatic neoplasms[31,32
]. This procedure is usually performed in specialized medical centers, which would support the concept of centralization. In our analysis, centralization of distal pancreas procedures over the last decade has not occurred.
Even though the definition of utilization of laparoscopy in our analysis was broad, it appears that at a nationwide level, laparoscopy is underutilized for distal pancreas resection despite sufficient evidence of its benefit. Centralization of distal pancreas resections to high volume centers does not appear to be occurring in the United States, but this does not appear to affect overall quality. During the course of this study survival and extent of lymph node harvest has not changed.
We can conclude that there is room for improvement in distal pancreas resection in the United States.