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* Population Health Sciences, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
Department of Surgery, Hospital for Sick Children, Toronto, Ontario, Canada
Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
|| the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONREFERENCES |
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Methods. All Ramstedt pyloromyotomies in the province of Ontario between 1993 and 2000 were reviewed. Children with complex medical conditions or prematurity were excluded. Cases done by general surgeons were compared with those done by pediatric surgeons, specifically examining hospital stay and complications.
Results. Of 1777 eligible infants, 67.9% were operated on by pediatric surgeons and 32.1% by general surgeons. Total and postoperative lengths of stay were longer in the general surgeon group compared with the pediatric surgeons (4.31 vs 3.50 days for length of stay; 2.95 vs 2.25 days for postoperative length of stay). The general surgeons had a higher overall complication rate (4.18% vs 2.58%). The incidence of duodenal perforation among general surgeons was almost 4 times that of pediatric surgeons (relative risk: 3.65; 95% confidence interval: 1.43-9.32). Of the 4 infants who required repeat surgery because of an incomplete pyloromyotomy, all were originally operated on by a general surgeon. Analysis of the effect of surgeon volume on outcomes suggested that higher volume resulted in better outcome in both groups.
Conclusion. Subspecialist pediatric general surgeons achieve superior outcomes for children who undergo Ramstedt pyloromyotomy.
Key Words: pyloric stenosis • subspecialization • patient volume • pediatric surgery • general surgery • outcomes analysis
Abbreviations: GS, general surgeon • CIHI, Canadian Institute for Health Information • ICD-9, International Classification of Diseases Ninth Revision • PGS, pediatric general surgeon • LOS, length of stay
Hypertrophic pyloric stenosis affects approximately 1 of every 400 children. Most present at ~1 month of age with nonbilious vomiting and undergo surgical treatment with the Ramstedt pyloromyotomy. Because of the simplicity of the operation, the usually excellent outcome, and the frequency of the condition, many general surgeons (GSs) are trained and qualified to perform it. However, there has been ongoing controversy about whether this is appropriate. A number of authors have suggested that outcomes are excellent in the hands of GSs,1–4 whereas others suggest that specialty-trained pediatric surgeons may have superior outcomes.5,6 The difficulties in assessing this issue include the very low rate of complications after pyloromyotomy and the lack of a population-based approach in most of the previous studies. Our goal was to address this question using a population-based approach and including a large number of infants.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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Source of Data
Computerized data on hospital discharges in Ontario from the Canadian Institute for Health Information (CIHI) were used for fiscal years 1993 through 2000. A fiscal year runs from April 1 to March 31 of the following year. Collection of hospital discharge data for submission to CIHI is mandatory for all hospitals in Canada. Data are collected on all patients who are discharged from public, private, and federal hospitals in Ontario. The database includes patient demographic data for each hospital stay (birth date, gender, and residence) and clinical data (admission date, discharge date, length of stay, codes from the International Classification of Diseases, Ninth Revision [ICD-9]7 for discharge diagnoses [up to 16 fields], and surgical procedures performed).
Inclusions
All infants (<1 year of age) in Ontario who had a diagnosis of pyloric stenosis with an ICD-9 code 750.5 and a hospital admission for pyloromyotomy (ICD-9 code 43.3) in fiscal years 1993-2000 were included.
Exclusions
It was important to ensure that only patients who would have been eligible for surgery by either a GS or a pediatric general surgeon (PGS) were included. Therefore, 69 preterm or low birth weight infants (<2000 g) and 72 infants with other major medical conditions were excluded.
Follow-up Through Record Linkages
The Ontario health care number, which is unique to each individual, was available in the CIHI data from April 1, 1993, through March 31, 2001, and was essential in tracing individuals for their readmissions. Using health care numbers, each child was followed through record linkages in the CIHI database for 30 days from the time of discharge after pyloromyotomy.
Outcome Measures
The main outcome measures for this study were overall average total length of stay (LOS) in the hospital, postoperative LOS, surgical complications, and 30-day readmission rates. Surgical complications included ICD-9 codes 998.0 (postoperative shock), 998.1 (hemorrhage or hematoma complicating a procedure), 998.3 (disruption of operation wound), 998.4 (accidental puncture or laceration during a procedure, hereafter referred to as duodenal mucosal perforation), 998.5 (postoperative infection), 998.6 (persistent postoperative fistula), and 998.8 to 998.9 (other specified or unspecified complication of procedure). All outcome measures were compared between 2 surgeon groups: 129 GSs and 17 PGSs. GSs were defined as those with specialty certification in general surgery from the Royal College of Surgeons of Canada. PGSs were defined as GSs who had 2 additional years of subspecialty training in pediatric general surgery and had achieved specialty certification in pediatric general surgery from the Royal College of Surgeons of Canada.
Pyloromyotomies all were performed in hospitals and were billed to the Ontario Health Insurance Plan for reimbursement of the services rendered. Each physician's unique Ontario Health Insurance Plan billing number in the billing record was obtained and was then linked to the Canadian National Physician Database to determine the specialty of the surgeon who performed the surgery. The Canadian National Physician Database contains data on sociodemographic characteristics (including specialty training) and billing activities of all licensed physicians in Canada.
Statistical Analysis
Rates of pyloromyotomy were expressed as per 1000 Ontario population of infants, with population figures based on the Canada Census data. Statistical comparisons were assessed using the 
2 test for nominal data (eg, surgeon groups, gender of the patient) and the t test for continuous variables (eg, age, birth weight, total LOS, postoperative LOS). Multivariable logistic regression was used to evaluate the independent association among surgeon group, volume, and surgical complications. Year of operation and type of hospital (teaching vs community) were included in the logistic regression to account for potential confounding effect. The effect of surgeon volume on outcome was also modeled using random-effects hierarchical logistic regression model. The software package MlwiN (Multi-Level Modeling: Window-based version)8 was used in this hierarchical logistic regression analysis, which took into account the hierarchical nature of the data, with patients clustered within surgeons and surgeons clustered within hospitals. Because surgical volume was vastly different between the 2 surgeon groups, the relationship between volume and outcome was also analyzed separately for each group. All analyses were performed using the Statistical Analysis Systems software.9
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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Pyloromyotomy Rates, 1993-2000
Table 1 shows the rates of pyloromyotomy from 1993 to 2000. Except for a slight increase in rates in 1998 and 1999, there was a general declining trend from 1.71 per 1000 in 1993 to 1.61 per 1000 in 2000, representing an overall decrease of 6% over 8 years. In 1993, the 2 surgeon groups shared ~50% of the volume of pyloromyotomies. Since 1993, there was a steady decrease of these operations performed by GSs. By 2000, 76.8% of all pyloromyotomies in Ontario were performed by pediatric surgeons.
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Although our regression model showed that hospital volume had a significant negative relationship with postoperative LOS, this relationship did not hold when subspecialty training (general vs pediatric surgeon) was included in the analysis. This indicates that the majority of the variance in postoperative LOS was in fact explained by the surgeon subspecialty training. Similar results were observed using total LOS as the outcome variable. Subspecialty training remained the most significant independent predictor in postoperative LOS.
Postoperative Complications
The GS group had a higher overall complication rate compared with the pediatric surgeons (4.18% vs 2.58%), although the difference was not statistically significant (Table 2). The risk of duodenal mucosal perforation among GSs was almost 4 times that of the pediatric surgeons (relative risk: 3.65; 95% confidence interval: 1.43-9.32). However, this risk ratio was not statistically significant after adjusting for surgical volume, suggesting that surgeon volume had some influence on outcome in both groups. Figure 3 shows the predicted probabilities of duodenal mucosal perforation by surgical volume estimated from a logistic regression model. General or pediatric surgeons who performed 5 or more cases per year had relatively low predicted probabilities (<1%) of duodenal mucosal perforation during surgery (Fig 3). Although not statistically significant, GSs with a volume of <5 cases per year had substantially higher predicted probabilities of duodenal mucosal perforation than higher volume GSs or PGSs.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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The affect of subspecialty surgical training on patient outcomes has been studied in a number of adult series. In the areas of vascular surgery11,12 and several types of cancer surgery,13–17 outcomes have been shown to be improved when the procedures are performed by subspecialty-trained individuals. However, many of these studies have been flawed by virtue of their retrospective nature and failure to use a population-based approach. Similarly, several studies in the pediatric population have demonstrated superior outcomes when children have undergone pyloromyotomy5,6 or appendectomy18,19 by PGSs as compared with GSs, although some of these studies suffer from the same limitations. The recent study by Pranikoff et al6 used a statewide database to address this issue for pyloromyotomy. Although their total number of patients was smaller than ours (780), their results were very similar, suggesting that our findings are applicable in the context of the American health care system as well as the Canadian system.
In addition to specialty training, there are several factors that may have an impact on outcome for children with pyloric stenosis. The factor that has been studied most in recent years is the effect of surgeon or institution volume on patient outcome. Although some studies have failed to demonstrate an effect of volume on outcome,20 most studies have found a correlation between surgeon or institution volume of cases and a variety of positive outcome measures.11,15,21–23 This has also been true for the management of nonsurgical diseases such as myocardial infarction.24 Our data suggest that volume is likely an important contributing factor to the difference in outcomes between GSs and PGSs. Our data also suggest that GSs who perform a higher volume of cases may have better outcomes. This fact supports the concept that GSs can achieve excellent outcomes but that these cases should be concentrated among a smaller group of GSs within a given community so that each individual maintains an adequate volume.
Another potential factor that may be unrelated to either subspecialization or volume is the use of specialized teams of nonsurgeons, such as anesthesiologists, critical care physicians, and nurses,25,26 and the expertise and experience of the primary care family physicians and pediatricians in the community. We were unable to capture data on this issue, but it is likely that institutions with full-time PGSs (mostly children's hospitals) also have a wide variety of specialized pediatric-oriented individuals in supportive roles.
What action should be taken from these data? In similar circumstances, many authors have drawn the conclusion that all such cases should be referred to subspecialist surgeons or high-volume institutions.27 In many competitive urban environments, this would seem to be the most effective way to achieve the highest quality of care possible. In the Canadian system, which attempts to rationalize care geographically, as well as in rural areas of the United States and many other countries, it would be impossible for all pyloromyotomies to be performed at a children's hospital by fully trained and board-certified PGSs. Therefore, the presence of these discrepancies in outcome must stimulate a process of education, mentoring, and focusing of community practices to the point that GSs who choose to care for children with pyloric stenosis can achieve the same outcomes as subspecialist PGSs. This might require centralization of cases within and among groups of GSs so that those with interest and expertise in dealing with infants would deal with a higher volume of children with pyloric stenosis. Chiefs of surgery at community hospitals must take responsibility for scrutinizing the outcomes for each of the GSs who perform pyloromyotomy to determine whether they meet the standards established by the pediatric general surgery group in this and other studies. In addition, development of additional specialized training programs for GSs who wish to take care of routine surgical problems in children might be useful in promoting better outcomes.
Limitations
First, although the database used in this study was population based, it was not designed for research but rather for administrative purposes. Therefore, it limits our capability to account for clinical factors that may influence postoperative outcome. Nevertheless, we were able to demonstrate a surgeon volume–outcome relationship with LOS and risks of surgical complications in our multivariable logistic regression analysis after adjusting for patient's gender, surgeon specialty, and surgeon volume.
Second, there could have been undercoding or incomplete documentation of surgical complications among different surgeons and across various hospitals. Few studies have validated face sheet data or administrative database data against the entire hospital record to assess the accuracy and completeness of coding of administrative data. Although we do not have direct assessment of the accuracy and completion of coding of postoperative complications in the CIHI data, chart abstraction studies conducted by others did not indicate a concern. For example, a recent study by Hawker et al,28 which measured the accuracy of administrative data for assessing outcomes after knee replacement surgery, suggested that although the agreement on complication data varied by organ system and type (ranged from 90.9% [urinary tract infection] to 100.0% [wound dehiscence]), the overall agreement for in-hospital complications was 96.8%. This study was also based on the Ontario CIHI data that we used in this study. Furthermore, there are no solid reasons for us to expect that the documentation of complication codes would have a differential distribution among PGSs and GSs.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Reprint requests to (J.C.L.) Rm 1526, Hospital for Sick Children, 555 University Ave, Toronto, Ontario M5G 1X8 Canada. E-mail: jacob.langer{at}sickkids.ca
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This article has been cited by other articles:
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  D. P. Ly, J. G. Liao, and R. S. Burd Effect of Surgeon and Hospital Characteristics on Outcome After Pyloromyotomy Arch Surg, December 1, 2005; 140(12): 1191 - 1197. [Abstract] [Full Text] [PDF]
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 T. To, A. Wajja, P. W. Wales, and J. C. Langer Population Demographic Indicators Associated With Incidence of Pyloric Stenosis Arch Pediatr Adolesc Med, June 1, 2005; 159(6): 520 - 525. [Abstract] [Full Text] [PDF]
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