Identification of Patients with Colorectal Liver Metastases Using an Administrative Database

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to 7/29/2008, 108 patients underwent PET/CT to evaluate pulmonary nodules. Of these, 27 patients (25%) had a history of cancer and 81 patients (75%) had no known cancer history. Of the 27 patients with a cancer history, 13 patients (48.1%) had PET/CT results that were concerning for malignancy and underwent a confirmatory biopsy following PET/CT. Of these patients, 11 of 13 (84.6%) were confirmed to have a malignancy. Of the remaining 14 patients (51.9%), 12 had no activity on PET/CT and were recommended for short interval follow-up, and 2 had findings consistent with widely metastatic disease (no lung biopsies were performed). At final follow-up, no negative PET/CT finding has subsequently proven to be a malignancy. In this subset, the sensitivity of PET/ CT to predict a malignancy was 100%, the specificity was 85.7%, the positive predictive value (PPV) was 84.6%, the negative predictive value (NPV) was 100%, and accuracy was 92.0%. Of the 81 patients with no cancer history, PET/CT findings lead to 38 patients (46.9%) undergoing biopsy: 14 (36.8%) bronchoscopic and 24 (63.2%) surgical. Of these, 27 of 38 (71%) were confirmed to have a malignancy. Of the 43 (53.1%) in which no biopsy was pursued, 40 had no activity on PET and 3 were found to have widely metastatic disease (all 3 were confirmed malignancies by biopsy of non-pulmonary tissue). As of follow up, 2 patients with a negative PET were subsequently diagnosed with a malignancy in the incidentally found lesion. In this subgroup, the sensitivity of PET/CT to predict a malignancy was 92.6%, the specificity was 78.4%, the PPV was 71.4%, the NPV was 95.3%, and accuracy was 84.6%. The overall median follow up was 36 months (range 12 - 54). Mortality in the patients with confirmed malignancy with and without a prior cancer history were 45.5% (5/11) and 63.0% (17/27), respectively. Conclusion: PET/CT is occasionally used to validate CXR and CT findings of incidental pulmonary nodules suspicious for a malignancy. The clinical history of cancer appears to impact the accuracy of the PET/CT interpretation, likely related to a more focused clinical differential. Nodules that have a low suspicion for malignancy by PET criteria can be considered for close radiological observation rather than immediate biopsy.

rior-first approach begins with the patient supine. The skin and abdominal wall are divided through a transverse incision. Necessary procedures involving the abdominal viscera are accomplished, culminating with division of the aorta and vena cava at the desired level. The vertebrectomy is performed next; this requires piecemeal removal of the intervertebral disks above and below the chosen vertebral body. Then the vertebral body is removed, again piecemeal, using bone wax to control bleeding between rongeur bites. There is generally about w500 ml of blood loss at this point, as the volume of bone is w75 cm3. Division of the cauda equina, dura, and vessels in the spinal canal is the next step. Then a long needle is inserted through the paraspinous tissue toward the spinous process to mark the place where the posterior elements are to be removed. A large adhesive plastic drape is applied and the patient is turned to the prone position. A transverse skin incision is made, which connects with the prior anterior incision. The needle placed previously is located and the posterior bony elements are resected. Closure of the body wall is completed with the patient prone. The time required to perform a hemicorporectomy by the posterior-first approach is less than that required using the anterior-first approach. Conclusions: 1. This is the first description of this technique, to our knowledge. 2. The volume of blood loss during hemicorporectomy is directly related to the volume of cancellous bone resected during spinal division. 3. The posterior-first approach is faster than the anterior-first approach, requires piecemeal resection of less cancellous bone, and therefore entails less blood loss. 4. Division of the contents of the spinal canal is also technically easier using the posterior-first approach. 5. We consider the posterior-first approach to be the operative strategy of choice.

30.18. Elective Division of the Spine during Hemicorporectomy. D. A. Horwitz, D. C. Crafts, F. E. Johnson; Saint Louis University School of Medicine, Saint Louis, MO

30.19. Identification of Patients with Colorectal Liver Metastases Using an Administrative Database. N. S. Becker,1 P. Richardson,2 N. S. Abraham,3 D. A. Anaya,1 Michael E. DeBakey1; 1Department of Surgery, Houston, TX; 2 Houston Center for Quality of Care & Utilization Studies, Houston, TX; 3Department of Medicine, Gastroenterology, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, Houston, TX

Introduction: Hemicorporectomy is performed most often for those with spinal cord injury who develop pressure ulcers and intractable sepsis. It is the only operation that involves deliberate division of the spine. The optimal technique of spinal division is not clear. We present our experience. Methods: Four patients underwent hemicorporectomy. In two, division of the spine began with an anterior approach and vertebrectomy; division began with a posterior approach and resection of the posterior spinal elements in the other two. Results: The posterior-first approach begins with the patient prone. Excision of the posterior bony elements is carried out through a transverse skin incision. The volume of cancellous bone to be resected is w10 cm3, and the usual blood loss is < 50 ml. This is followed by transection of the dura and cauda equina. Control of bleeding from the arteries and venous plexus in the spinal canal is technically easy using this approach. Closure of the dura is next. The intervertebral disk to be divided is marked with a radio-opaque object. The wound is covered with a large plastic adhesive drape and the patient is turned to the supine position. A low transverse abdominal incision is made, which connects with the posterior incision. Division of the trunk proceeds as usual, including division of the vena cava and aorta at the desired level. An abdominal x-ray is obtained to identify the radio-opaque object at the interspace to be divided. The disk is divided, the lower body is removed, the patient is turned again, and the body wall closure is completed with the patient prone. Spinal division from the ante-

Introduction: Liver metastases (LM) develop in a large number of patients with colorectal cancer (CRC). Current management and outcomes data for these patients are largely derived from single-institutions with medium- to high-volume experience. These data may be limited when applied to lower-volume practices or those outside of cancer referral centers. Further, new therapeutic strategies are emerging in this field and must be evaluated, preferably on a population-level. Large multi-institutional databases provide a valuable source of information that can be used for this purpose. However, miscoding and/or incompleteness of information limits their reliability, hence the need for database validation prior to use for these analyses. This study examines the database of the Veterans Administration (VA) system to determine if the information contained within the database can be used to identify patients with CRC LM, and to develop an algorithm to accurately and reliably select such patients. Methods: Patients aged 18-99 years evaluated for CRC at a major VA facility (1997-2008) were identified using the national VA database (n ¼ 1,671). Administrative ICD-9 and CPT codes used for recording liver-related diagnosis/procedures were selected and used to classify the cohort into those potentially having LM (cases, n ¼ 308) and those with CRC and no LM (controls, n ¼ 1,363). The cases were matched 1:2 to controls based on year of CRC diagnosis, resulting in a study sample of 924 patients. Using a standardized method, local medical records were then abstracted to determine whether each case and control met clinical criteria

ASSOCIATION FOR ACADEMIC SURGERY AND SOCIETY OF UNIVERSITY SURGEONS—ABSTRACTS for LM. The positive predictive value (PPV) of each administrative code was calculated, and a multivariate analysis was performed to determine which codes were independent predictors of LM. These codes were used to develop a diagnostic algorithm for CRC LM. The discrimination of the model was calculated using the c-statistic. Additionally, contingency tables estimates for the total cohort were calculated, from which sensitivity, specificity, PPV, negative predictive value (NPV) and percent agreement were derived. Results: The study included data from 308 cases and 616 controls. The majority of patients were male (97%) and mean age was 67 years. Three administrative codes were found to independently predict the presence of CRC LM: ICD-9 diagnosis code 155.2 (odds ratio [OR] 9.7, 95% confidence interval [CI] 2.5-38.4, p ¼ 0.001), ICD-9 diagnosis code 197.7 (OR 84.6, 95% CI 52.9-135.3, p < 0.0001), and ICD-9 procedure code 50.22 (OR 5.9, 95%CI 1.3-25.5, p ¼ 0.01).The diagnostic algorithm was defined as the presence of any of these three codes. Its discrimination (c-statistic) was 0.88 with sensitivity of 68.7%, specificity of 97.3%, PPV of 87.7%, and NPV of 91.8%. The percent agreement between the algorithm and the clinical diagnosis of CRC LM was 91%. Conclusions: This study determined that the VA administrative database can be used to identify patients with CRC LM. The developed algorithm (ICD-9 diagnosis codes 155.2 and/or 197.7 and/or ICD-9 procedure code 50.22) is highly predictive of CRC LM diagnosis and can be used for research to study colorectal cancer liver metastases at a population level.

PEDIATRICS AND DEVELOPMENTAL BIOLOGY 3: OUTCOMES/TRAUMA AND DEVELOPMENT 31.1. A Comparison of Pediatric Injuries from Bicycles, Dirtbikes, and ATVs. S. R. Shah, M. D. Fox, M. Jegapragasan, B. A. Gaines; Children’s Hospital of Pittsburgh, Pittsburgh, PA Introduction: Previous studies have clearly shown that all-terrain vehicles (ATVs) are more dangerous than bicycles for children. These reports have demonstrated that pediatric ATV injuries are more severe, result in a greater percentage of multiple injuries, and more often lead to operative interventions than bicycle injuries. However, currently there is not an adequate understanding of how pediatric dirtbike injuries compare to other motorized and non-motorized vehicles used by children. In this study we hypothesized that pediatric dirtbike injuries would be more severe than bicycle injuries and would instead be more similar to the injury patterns associated with ATV use in children. Methods: A retrospective review of all children injured on bicycles, dirtbikes, and all-terrain vehicles between 2002 and 2007 at a Level I Pediatric Trauma Center was performed. Patients were identified through an institutional trauma registry. Results: There were 941 bicycle (B), 300 dirtbike (D), and 417 ATV (A) injuries identified during the study period. The majority of injured patients in all three groups were males, with a significantly greater male-to-female injury ratio on dirtbikes compared to the other groups (D vs. B: p < 0.01, D vs. A: p < 0.01). The average age was highest in children sustaining dirtbike injuries, followed by ATV injuries, then bicycle injuries (p < 0.01). Mean injury severity scores (ISS) were significantly higher in dirtbikeand ATV-related injuries when compared to bicycle-related injuries (B vs. D: p ¼ 0.02, B vs. A: p < 0.01). Similarly, the overall hospital length of stay was greater in children injured on dirtbikes and ATVs compared to those injured on bicycles (B vs. D: p ¼ 0.05, B vs. A: p < 0.01). Helmet use was found to be greatest among those injured on dirtbikes, followed by ATVs, and then bicycles (p < 0.01). Conclusions: Although dirtbike injuries occur in older children and are associated with greater helmet use when compared to ATVs and bicycles they still lead to significantly greater injury severity and longer

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hospitalizations compared to bicycles. This more severe injury pattern with dirtbikes and ATVs compared to bicycles suggests that dirtbikes should also be a focus of injury prevention efforts, similar to the regulatory and educational efforts addressing ATVs.

31.2. Blunt Traumatic Brain Injuries in Children - Predictors of Outcome. S. Islam,1 L. R. Vick,2 J. Schwannebeck2; 1 University of Florida, Gainesville, FL; 2University of Mississippi, Jackson, MS Purpose: Trauma accounts for 40% of pediatric mortality in the US, and traumatic brain injury (TBI) is the leading cause of death in this group. A number of factors have been proposed as predictors of outcome in TBI, however these have not been reliable. We reviewed our large experience with pediatric TBI to assess outcome predictors. Methods: We identified TBI (ICD9 850-854) in patients  16 years over a 5 year period. Data regarding demographics, injury type, ED and hospital care and outcome variables were collected . Severity of TBI was stratified by GCS scores (severe 8, moderate 9-11, mild 12-15). Multiple statistical tests including regression were used and p values less than 0.05 were considered significant. Results:437 patients were identified with TBI. 55% were mild, 10% moderate and 35% severe. In the severe group, a 43% fatality rate was noted. There were no differences between survivors or deaths in age, race, month of injury, time to presentation, mechanism of injury, initial heart rate, or temperature. Survival was independently predicted by initial and 24 hour GCS, ISS, systolic blood pressure, pupil size and response. ICP was monitored in less than 25% of severe TBI, and opening pressure was not different, while subsequent measurements were significantly higher in fatal cases. Overall length of stay was shorter in fatal injuries, but ICU stay was significantly longer. Of the survivors, 44% had significant neurologic issues at discharge which persisted in 40.7% at 6 week follow up. Neuropsychiatric consults were obtained in only 13.5% of survivors. Conclusions: Severe TBI has a high fatality rate and outcome is strongly correlated with SBP, pupil activity, and a low initial and 24 hour GCS. These predictors can be used to select patients for aggressive care including ICP and predict rehab needs.

31.3. Bowel Obstruction after Treatment of Intra-Abdominal Tumors. P. Aguayo, J. D. Fraser, A. Gamis, S. D. St. Peter, C. L. Snyder; The Children’s Mercy Hospital, Kansas City, MO Purpose: Tumors of the solid viscera are one of the most common types of pediatric malignancies. Due to the intra-abdominal location of many of these neoplasms, laparotomy and/or bowel resection are often necessary. Additionally, chemotherapy and radiation therapy may lead to bowel injury and obstruction. We reviewed our data over an eleven-year period to identify the incidence of obstruction as