In this study using a large national database, we reported several important findings to suggest significant trends in the management of ASBO and patient outcomes. While patients less frequently undergo operative interventions for ASBO, the timing of operation has shifted earlier in their hospital stay. Approximately one third of operative interventions were performed within 24 hours after the admission, increased from one quarter in previous years. The in-hospital mortality in ASBO patients with and without operative intervention significantly decreased over the study period. Similarly, the length of hospital stay trended down regardless of operative intervention. To our knowledge, this is one of the largest studies in the modern era to report the contemporary management of ASBO and patient outcomes.
One of the most significant findings we observed in this study was the trend toward earlier operation for ASBO. A long-standing dilemma surgeons have faced for centuries is on the management of ASBO, particularly (1) whether to operate and (2) when to operate. In the past, a mandatory surgical intervention was considered as the mainstay of treatment for ASBO. This practice pattern is well-represented in the motto, “Never let the sun rise or set on a small bowel obstruction.” However, it has been recently reported that up to 70% of patients with SBO were managed nonoperatively at 13 hospitals across North America, all of which participated in the American College of Surgeons National Surgical Quality Improvement Program.23 On the other hand, a failure to identify the patient with strangulated ASBO and subsequent bowel ischemia is associated with the significant delay in surgical interventions. In these cases, the mortality rate was reported to be as high as 40% in previous literature.24
There are an increasing number of institutions where the use of water-soluble contrast in a trial of nonoperative management of ASBO is standard practice. In a recent multi-institutional study of water-soluble contrast for ASBO, 11 (79%) of 14 participating institutions had previously implemented the water-soluble contrast challenge for the management of ASBO. There was also a significantly lower rate of operative exploration in the water-soluble contrast group (20.8% vs. 49.0%, p < 0.0001) and a significant trend toward lower operative rate, the latter of which may be contributed by an increase in the administration of water-soluble contrast.17 This algorithm includes administration of water-soluble contrast via nasogastric tube, and then serial abdominal radiographs are taken every 4 to 6 hours. The indication for surgical intervention is usually defined as a failure to pass contrast to the ascending colon within 8 to 24 hours.15 The benefits of this protocol are twofold: serial radiographs follow the passage of contrast and can help diagnose whether the patient has a complete obstruction in an objective fashion. The second potential benefit is therapeutic from the contrast's high osmolarity that facilitates decrease in edema of the small intestine and help relieve intraluminal pressure. While this protocol helps guide the surgeon, the most important decision is to determine, within 24 to 48 hours, whether to a patient with ABSO requires an operation.
To date, little has been described about recent changes in the practice patterns and patient outcomes for ASBO in population-based studies. Our study clearly demonstrates an improved survival of patients with ASBO in the United States over the last decade. In the United Kingdom, Peacock et al27 reported the data from the National Emergency Laparotomy Audit, a nationwide surgical quality improvement program database in England and Wales. Between December 2013 and November 2015, 31.3% of emergency laparotomies with either adhesiolysis or bowel resection for SBO were performed less than 24 hours after admission. The overall 30-day mortality was 7.2% in their cohort. Behman et al.28 conducted a retrospective population-based study using a Canadian administrative database to evaluate the trends in the management of ASBO from 2005 to 2014. While their study also showed a significant increase in the proportion of patients who underwent surgery within 1 day, the proportion of patients who underwent surgery overall increased significantly.
There are several limitations to our study. First, the NIS database is an administrative database, thus not structured for the use in research. Although the database includes a large number of patients discharged from the US hospitals, limited clinical data are available to be adjusted in the multivariable analysis. There are several important factors associated with patient outcomes in ASBO, including previous history of abdominal surgeries, previous admissions for ASBO, severity grades, and primary admitting service (surgery vs. others).29,30 For that reason, this study focused on describing the trends in practice pattern and patient outcomes.31 Furthermore, we determined to include ASBO patients between 2003 and 2013, as we believe that water-soluble contrast have been more commonly used for ASBO in the United States since the early 2000s, although this period can be arbitrary.14,15,32 Second, we were unable to evaluate the impact of laparoscopic procedures. The utility of laparoscopic procedure for ASBO remains controversial.33,34 We believe that the NIS database is not suitable to perform the analysis to compare patient outcomes between different treatment options because of limitations of the database. Third, significant trends observed in our study may not apply to each surgeon- and hospital-level across the country. Significant disparities in the practice pattern and outcome may still exist in ASBO.35 Finally, we would like to emphasize that the results of this study should not interpreted as if the change in practice patterns have improved the outcome of patients with ASBO. There are several factors, including recent advances in initial resuscitation, medical optimization of patients with comorbidities, and postoperative care in the intensive care unit, all of which may have contributed to these improved patient outcomes.
The results of this study suggest that there has been a significant paradigm shift in the management of ASBO from 2003 to 2013. We observed an overall decrease in the number of patients who underwent an operative intervention but a shift to intervention earlier during hospitalization. At the same time, in-hospital mortality and HLOS have significantly improved. Further studies are warranted whether recent changes in practice pattern are associated with improved patient outcomes.
The authors declare no conflicts of interest.
Corresponding author: Matsushima; study concept, design: Matsushima, Sabour, Park, Strumwasser, Inaba, Demetriades; data collection and analysis: Matsushima, Sabour, Park; writing: Matsushima, Sabour; critical revision: Park, Strumwasser, Inaba, Demetriades.
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Martin D. Zielinski, M.D. (Rochester, Minnesota): Good morning. Drs. Rotondo and Reilly, Publication and Program Committee, thank you for the opportunity to discuss this outstanding paper. Dr. Matsushima, thank you for highlighting the care of small bowel obstruction patients.
My interest in this field was actually due to a delayed diagnosis of a strangulation obstruction as a chief resident, and that really drove me into doing some research in this area, because I knew there must be a better way to manage small bowel obstruction patients which the authors have successfully highlighted.
They present a secondary analysis of the National Inpatient Sample and have studied non-operative versus operative management of adhesive small bowel obstruction in the setting of increasing national trends to use small bowel obstruction protocols, which heavily rely on CT imaging and Gastrografin challenge protocols.
They hypothesize that there would be trends towards less frequent operations, but that the operations would be earlier in the patients' critical course.
To answer their questions, the NIS was utilized from 2003 to 2013, and identified nearly two million patients. Of these patients, almost half of them underwent operative exploration.
They were able to show multiple improvements over that decade in terms of mortality, lesser rates of bowel resection, and lesser durations of stay.
The authors also highlighted, however, that there was no ability to proscribe a cause and effect relationship with these improvements in clinical outcomes to the protocols, but their results certainly are intriguing. This was really a quite well-done paper, so I only have a few questions:
Why did you choose the years 2003 – 2013? The Gastrografin challenge has been around since the early 1990's, and the push to move small bowel obstruction protocols really was coming in in the late 2000's. I would also bet that there would be a continued and probably even stronger national trends to further support your hypothesis after 2013.
Secondly, why didn't you stratify for hospital characteristics, particularly the ones with differences such as bed size and teaching status?
This study highlights the inability to really use some of these national databases designed for purposes other than quality and research. For instance, we have no idea which hospitals are using small bowel obstruction protocols, and how many more protocols were implemented in these institutions across the country throughout the study period.
Really, to me, there are two major takeaways from this paper. First, the clinical protocols for emergency general surgery diseases will likely become more commonplace, and hopefully improve patient outcomes in the next years and decades;
And secondly, that we need a reliable national data source that captures both operatively and non-operatively managed patients, that also contains data points specific to disease processes to allow us to control for disease severity, physiologic status, and hospital parameters, instead of relying on billing databases to drive our research. With this more specific information, we as a community of emergency surgeons can determine the cause and effect this and other similar protocols will have to further improve patient care. Thank you.
David Harrington, M.D. (Providence, Rhode Island): Thank you. The rate of surgery of 40 percent was a shocker to me, and I was wondering if you could give us some information as to whether those were immediate operations – people came in with, you know, compromised bowel and went to surgery – and how many of those were, kind of, failure of management, meaning, detected later. That would be an important distinction for me.
Kimberly A. Davis, M.D., M.B.A. (New Haven, Connecticut): Thank you very much for your excellent presentation and an interesting study. A number of papers have previously demonstrated that the type of surgery performed is more likely to be linked to lengths of stay and outcomes, so can you give us some insight as to how many of these patients underwent their surgeries laparoscopically versus via more traditional open techniques? Thank you.
Kazuhide Matsushima, M.D. (Los Angeles, California): Dr. Zielinski, thank you so much for your kind and invaluable comments. We certainly acknowledge your contribution to this area. Please let me start to address your questions first.
In terms of a study period, I agree, the Gastrografin challenge has been around since 1990's, but we felt that the surgeons in the U.S. became familiar with the Gastrografin study in early 2000, that's why we chose the 2003. I know it's an arbitrary number, so that's one of the limitations.
The second question regarding the hospital level characteristics, we did control in our logistical regression model; however, like I briefly mentioned, I can imagine there is a significant variations in terms of management of small bowel obstruction between institutions, so that's something we have to address in future studies.
The rate of operative intervention – 46 percent in 2003 – it's higher than described; however, I think the rate of successful non-operative management – 70-80 percent – in previous literature, is based on the data at institutions with a high-volume of patients with small bowel obstruction; however, if you include entire hospital across the country, the rate of operating intervention can be increased, such as 45-50 percent.
The question regarding laparoscopic surgery, which is another hot topic in adhesive small bowel obstruction, we did increase ICD-9 code for laparoscopic procedures, such as lysis of adhesions. I don't have an exact number, but in the previous study, the use of laparoscopic surgery has been increasing significantly in the last ten years, so I would think the number would be much higher in the last ten years.
Thank you so much.