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Biomedical subjects

Richard A Kozarek

Publications and source records attributed to Richard A Kozarek.

At least 19 recordsLinked to original sources
PubMed2006

Screening colonoscopy in very elderly patients: prevalence of neoplasia and estimated impact on life expectancy.

CONTEXT: Current guidelines do not include an upper age cutoff for colorectal cancer screening with colonoscopy. Although the prevalence of colonic neoplasia increases with age, life expectancy decreases. Thus, the benefit of screening colonoscopy in very elderly patients may be limited. OBJECTIVE: To compare estimated life-years saved with screening colonoscopy in very elderly vs younger persons. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study conducted among 1244 asymptomatic individuals in 3 age groups (50-54 years [n = 1034], 75-79 years [n = 147], and > or =80 years [n = 63]) who underwent screening colonoscopy at a US teaching hospital and clinic. MAIN OUTCOME MEASURES: Prevalence of various types of colon neoplasia; estimated gain in life expectancy, calculated as life expectancy--(life expectancy during polyp lag time + life expectancy after colorectal cancer diagnosis); and comparison of mean gain in life expectancy across the 3 groups. Life expectancy and mortality data were derived from life tables, previous studies, and national databases. RESULTS: The prevalence of neoplasia was 13.8% in the 50- to 54-year-old group, 26.5% in the 75- to 79-year-old group, and 28.6% in the group aged 80 years or older. Despite higher prevalence of neoplasia in elderly patients, mean extension in life expectancy was much lower in the group aged 80 years or older than in the 50- to 54-year-old group (0.13 vs 0.85 years). In sensitivity analysis, with longer polyp lag times the mean extension in life expectancy decreased more in the elderly than in the younger patients; alternatively, if it was assumed that a smaller proportion of adenomas progress to colorectal cancer, the mean extension in life expectancy decreased less in the elderly than in the younger patients. CONCLUSIONS: Even though prevalence of neoplasia increases with age, screening colonoscopy in very elderly persons (aged > or =80 years) results in only 15% of the expected gain in life expectancy in younger patients. Screening colonoscopy in very elderly patients should be performed only after careful consideration of potential benefits, risks, and patient preferences.

Aged↗
PubMed2006

Risk stratification for colon neoplasia: screening strategies using colonoscopy and computerized tomographic colonography.

BACKGROUND & AIMS: We developed a risk index to identify low-risk patients who may be screened for colorectal cancer with computerized tomographic colonography (CTC) instead of colonoscopy. METHODS: Asymptomatic persons aged 50 years or older who had undergone screening colonoscopy were randomized retrospectively to derivation (n = 1512) and validation (n = 1493) subgroups. We developed a risk index (based on age, sex, and family history) from the derivation group. The expected results of 3 screening strategies--universal colonoscopy, universal CTC, and a stratified strategy of colonoscopy for high-risk and CTC for low-risk patients--were then compared. Outcomes for the 3 strategies were extrapolated from the known colonic findings in each patient, using sensitivity/specificity values for CTC from the medical literature. Results were validated in the validation subgroup. RESULTS: In the derivation subgroup, universal colonoscopy detected 94% of advanced neoplasia and universal CTC detected only 70% and resulted in the largest total number of procedures and number of patients undergoing both procedures. The stratified strategy detected 92% of advanced neoplasia, requiring colonoscopy in 68% and CTC in 36% of patients, with only 4% having to undergo both procedures. In the validation subgroup, universal colonoscopy detected 94% and universal CTC detected 71% of advanced neoplasia, whereas the stratified strategy detected 89%, requiring colonoscopy in 64% and CTC in 40%. Unlike universal CTC, the stratified strategy was independent of assumptions for CTC sensitivity, specificity, and threshold for colonoscopy. CONCLUSIONS: The stratified strategy based on our risk index may optimize the yield of colonoscopic resources and reduce the number of patients undergoing colonoscopy.

Colonic Neoplasms↗
PubMed2005

Risk of proximal colon neoplasia with distal hyperplastic polyps: a meta-analysis.

BACKGROUND: Most guidelines for colorectal cancer screening do not consider distal hyperplastic polyps (HPs) to be markers for proximal colon neoplasia. However, many studies have shown an increased risk of proximal neoplasia (PN) in patients with distal HPs. We performed a systematic review to assess the association between distal HPs and PN. METHODS: We identified studies that compared the prevalence of PN and proximal advanced neoplasia in patients with distal HPs vs controls. Two masked investigators extracted data on individuals with distal HPs, distal adenomas, or no distal polyps. Using the DerSimonian and Laird method, we calculated summary risk ratios. Extensive subgroup analysis was performed. RESULTS: The prevalence of PN and proximal advanced neoplasia in persons with distal HPs was 26.0% and 4.4%, respectively. In studies comparing the risk of PN in patients with distal HPs vs those with no distal polyps, the summary risk ratio was 1.81 (95% confidence interval, 1.20-2.73). However, this increased risk disappeared if only high-quality studies on screening patients were considered. The risk ratio was 0.69 (95% confidence interval, 0.60-0.80) when comparing the risk of PN in those with distal HPs vs those with distal adenomas. CONCLUSIONS: Overall, patients with distal HPs have an intermediate risk of PN compared with those with distal adenomas or no distal polyps; however, in asymptomatic screening individuals, there is no increased risk of PN or proximal advanced neoplasia. The discovery of HPs on screening flexible sigmoidoscopy should not automatically prompt follow-up colonoscopy.

Adenoma↗
PubMed2005

Risk of proximal colorectal neoplasia among asymptomatic patients with distal hyperplastic polyps.

PURPOSE: Many guidelines on colorectal cancer screening do not consider distal hyperplastic polyps to be a marker for proximal neoplasia. However, 11 of 17 published studies have shown an increased risk of proximal neoplasia in patients with distal hyperplastic polyps. Our goal is to assess the risk of proximal neoplasia in asymptomatic patients with distal hyperplastic polyps, compared to those with distal tubular adenomas or no distal polyps. METHODS: We assessed proximal (cecum, ascending, transverse colon and splenic flexure) and distal polyps in patients undergoing screening colonoscopy, classifying them into 3 groups: distal hyperplastic polyps only; distal adenomas with or without hyperplastic polyps; no distal polyps. The prevalence of proximal neoplasia and advanced neoplasia (polyps > or =1 cm, villous adenomas, or cancer) was compared among these groups. RESULTS: Of 2357 patients, 427 (18%) had neoplasia, including 103 (4%) with advanced neoplasia. Proximal neoplasia occurred in 175 (9%) of 1896 patients with no distal polyps, compared with 28 (12%) of 237 with distal hyperplastic polyps (P = 0.20) and 64 (29%) of 224 with distal adenomas (P <0.0001). Proximal advanced neoplasia occurred in 39 (2%) patients with no distal polyps, compared with 4 (2%) with distal hyperplastic polyps (P = 0.70) and 9 (4%) with distal adenomas (P = 0.13). CONCLUSIONS: Patients with distal hyperplastic polyps, unlike those with distal adenomas, do not exhibit an increased risk for proximal neoplasia or proximal advanced neoplasia compared to those with no distal polyps. The discovery of hyperplastic polyps on screening sigmoidoscopy should not prompt colonoscopy.

Adenoma↗
PubMed2005

Outcomes following resection of invasive and noninvasive intraductal papillary mucinous neoplasms of the pancreas.

BACKGROUND: Since any intraductal papillary mucinous neoplasm (IPMN) is at least premalignant, avoiding conversion to invasion by pancreatic resection should provide a survival advantage-but how much? METHODS: We reviewed 100 cases of IPMN that were resected. Survival was compared between 3 groups: noninvasive IPMN (n = 75), invasive IPMN (n = 25), and invasive ductal adenocarcinoma (n = 24), the latter matched by tumor-node-metastasis (TNM) stage to the IPMN invasive group. RESULTS: The 5-year disease-specific survival was significantly better for the noninvasive IPMN group (100%) than the invasive IPMN group (46%). Tumor recurrence was infrequent with noninvasive IPMNs (1.3% benign IPMN). Recurrence was common in the invasive IPMN group (46%). Even the subgroup with stage 1 disease had a 25% recurrence of malignancy. Survival curves were not different (P = .11) between the cases matched by stage for those with invasive IPMN cases versus cases with ductal adenocarcinoma. CONCLUSION: Patients with the invasive form of IPMN will have a similarly poor survival as those with ductal adenocarcinoma. In patients thought to have a benign IPMN, these lesions should be removed to avoid conversion to invasive cancer and to preserve the opportunity for the more favorable prognosis observed in this study.

Adenocarcinoma, Mucinous↗
PubMed2005

Pancreatic necrosectomy: definitions and technique.

Pancreatic necrosis implies a permanent condition in which a portion of the pancreas loses its blood supply. This condition is irreversible, yet many cases of "necrosis" will, after recovery, culminate in a patient with a normal pancreas by computed tomography or endoscopic retrograde cholangiopancreatography. The problem is in our definitions. An understanding of this disease through its related definitions is required before judgment deems "necrosectomy to be appropriate." These definitions are of pancreatic ductal disruption, peripancreatic fluid collections, pseudocyst, pancreatic abscess, and pancreatic necrosis. The technique of necrosectomy removes mature "necrosum" and is described in this article. Once necrosectomy is completed, the surgeon still depends on the continued support of interventional radiology through regular exchange of large-bore pancreatic drains. In our institution, many of these drain sites are placed at some time before necrosectomy. Once the team method has been implemented, the following improved outcomes will result--lowered need for necrosectomy and single digit mortality.

Biopsy, Needle↗
PubMed2005

Screening colonoscopy in Chinese and Western patients: a comparative study.

OBJECTIVES: The aim of this study was to compare findings on screening colonoscopy in a Chinese cohort versus a concurrent Western cohort. METHODS: Asymptomatic adults aged 40 years or older concurrently underwent screening colonoscopy in two hospitals, one in Taiwan and the other in Seattle. The prevalence and distribution of colonic neoplasia and advanced neoplasia (defined as an adenoma >or=10 mm or with villous, high-grade dysplastic, or malignant features) were compared between the two groups. RESULTS: The Taiwan cohort was composed of 1,456 subjects. Colonic neoplasms were found in 214 (14.7%), advanced neoplasms in 58 (4%), and colon cancers in 4 subjects (0.3%). The Seattle cohort was composed of 3,403 subjects. Neoplasms were found in 705 (20.7%), advanced neoplasms in 166 (4.9%), and cancers in 11 subjects (0.3%). Age and male sex were risk factors for neoplasia in both groups. The adjusted risk ratio was 1.30 (95% confidence interval: 1.08-1.57) in Western versus Chinese patients. However, the prevalence of advanced neoplasms was not statistically different between the two cohorts. The Chinese cohort had a higher proportion of distal neoplasia (66.4%vs 52.6%; p= 0.0004). The sensitivity of a sigmoidoscopic screening strategy for detecting advanced neoplasia was higher in Chinese (79.3%) than in Western patients (67.5%). CONCLUSIONS: Compared to Westerners, Chinese patients have a slightly lower prevalence of colon neoplasia (but not advanced neoplasia), more distal distribution of neoplasia, and higher likelihood of concomitant proximal advanced neoplasia and distal neoplasia. Colonoscopy is safe, well-tolerated, and a viable screening option in Chinese patients, but its advantage over sigmoidoscopy as a screening tool may be smaller.

Adult↗
PubMed2005

Palliation of gastric outlet obstruction and proximal small bowel obstruction with self-expandable metal stents: a single center series.

BACKGROUND: Self-expandable metal stents (SEMS) are being increasingly used to palliate malignant stenoses of the gastric outlet and proximal small bowel. Accordingly, we reviewed our experience in this setting. METHODS: Patients with gastric outlet or proximal small bowel stents were identified by reviewing hospital charts. Outcome criteria included survival data, need for reintervention, and clinical improvement. RESULTS: A total of 52 SEMS were placed in 36 patients with nonesophageal upper GI stenosis. Initial stent placement was successful in 92% and clinical improvement documented in 75%. Mean survival of patients who eventually died was 3.5 months. Seven patients are alive (mean follow-up, 5.0 months). Stent dysfunction occurred in 36% and required subsequent interventions. Biliary obstruction was documented in 50% of patients, 12 of whom had previously undergone biliary stenting and 5 who needed subsequent biliary decompression. CONCLUSIONS: Enteral stent placement has been reported to be an effective alternative for palliation of high-risk surgical patients with malignant gastric outlet and small bowel obstruction. Considering the short life expectancy of these patients and significant complications including stent migration, perforation, biliary obstruction, and need for subsequent endoscopic, radiologic and surgical interventions, the authors suggest that this procedure be performed in experienced centers on selected patients only and that biliary decompression be ensured early.

Adult↗
PubMed2004

A novel shape-locking guide for prevention of sigmoid looping during colonoscopy.

BACKGROUND: Looping of the endoscope in the sigmoid colon and other colonic segments often represents a significant challenge to the performance of comfortable, complete, and swift colonoscopy. This report describes the design and operation of a new device that addresses this problem, together with preliminary preclinical experience with this use of this shape-locking guide (SG-1). METHODS: The shape-locking guide is an overtube that can be converted from a flexible to a rigid configuration on demand. When in the rigid configuration, the shape-locking guide is designed to protect the colon wall from lateral forces exerted by the colonoscope. The shape-locking guide was evaluated in vitro by using an artificial colon model to learn how to operate it, and to assess feasibility for prevention of colon looping. In addition, safety was assessed in vivo in a pig model. RESULTS: In vitro, the shape-locking guide prevented colonic looping and, thereby, aided completion of "colonoscopy" in the artificial colon model. Subsequent in vivo studies demonstrated that use of the shape-locking guide is safe and feasible; it performed well with respect to ease of insertion and avoidance of sigmoid looping. There was no evidence of significant injury to the colon or adjacent abdominal viscera. CONCLUSIONS: This preliminary study shows that use of the shape-locking guide is safe and that it has performance characteristics that may assist the performance of colonoscopy. Human trials are being undertaken.

Animals↗
PubMed2004

Endoscopic stenting of colonic tumours.

Self-expandable metal stents (SEMS) are useful for the non-surgical relief of malignant colonic obstruction. They may be used both as a palliative measure and as a pre-operative bridge to facilitate a one-stage surgical resection of primary colonic tumours. SEMS may be placed endoscopically or by interventional radiologists without the use of endoscopy. In experienced centres SEMS can be successfully placed in approximately 90% of cases. Although it is known that the placement of these devices is feasible, there are no prospective trials comparing stent placement for colonic obstruction to routine surgical care. Additionally, there are no studies comparing the outcome of the method of placement (endoscopic versus radiological). This chapter reviews the types of expandable metal stent used for treatment of colonic obstruction, the indications for their insertion, their methods of insertion, and outcomes following insertion. Future research directions using expandable stents for colonic tumours are also addressed.

Adenocarcinoma↗
PubMed2003

Interferon-based adjuvant chemoradiation therapy after pancreaticoduodenectomy for pancreatic adenocarcinoma.

BACKGROUND: Patients with cancer who undergo pancreaticoduodenectomy (PD) followed by radiation and 5-fluorouracil (5-FU) therapy have experienced median overall survival from 18 to 24 months and an actuarial 2-year overall survival from 34% to 48%. We previously reported an 84% 2-year survival using a novel adjuvant chemoradiation protocol that included alpha interferon. This report describes the continued observations regarding this methodology with longer follow-up and more than twice the number of patients as the original report. METHODS: From July 1995 to May 2002, 43 patients with adenocarcinomas in the pancreatic head underwent PD at our institution. The mean age was 62 years (range 29 to 77) and 60% were men. Final pathologic findings were stage I (2%), II (12%), III (72%), and IVa (14%) while 84% had positive lymph nodes (average number of nodes positive was 3.2 nodes, (range 0 to 13). Tumor extended through the capsule of the surgical specimen in 70%. These patients then received our investigational protocol consisting of external-beam irradiation at a dose of 4,500 to 5,400 cGy (25 fractions over 5 weeks) and three-drug chemotherapy: continuous infusion 5-FU (200 mg/m(2) daily, days 1 to 35), weekly intravenous bolus cisplatin (30 mg/m(2) daily, days 1,8,15,22,29), and subcutaneous alpha, interferon (3 x 10(6) units, days 1 to 35). This chemoradiation was followed by continuous infusion 5-FU (200 mg/m(2) daily, weeks 9 to 14 and 17 to 22). Chemoradiation was generally initiated between 6 and 8 weeks after surgery. RESULTS: All patients completed radiation therapy. There were no deaths due to chemoradiation but 42% were hospitalized during chemoradiation, virtually all due to gastrointestinal toxicity. With a mean follow-up time of 31.9 months, 67% of the patients are alive. Therefore, the median survivorship has not been reached. Actuarial overall survival for the 1-, 2-, and 5-year periods was 95% (confidence interval [CI] = 91% to 98%), 64% (CI = 56% to 72%), and 55% (CI = 46% to 65%), respectively. CONCLUSIONS: This follow-up report further suggests overall survival may be improved for patients with adenocarcinoma in the pancreatic head using an adjuvant interferon-based chemoradiation protocol. These results are obtained despite a high incidence of node involvement and advanced tumor stage. From this limited patient series, the actuarial 2-year and 5-year overall survival rates suggest a potential for improved long-term survival. Further study of this regimen in a multiinstitutional setting is needed.

Actuarial Analysis↗
PubMed2003

Mucus is a predictor of better prognosis and survival in patients with intraductal papillary mucinous tumor of the pancreas.

The aim of our study was to examine the case histories of patients with intraductal papillary mucinous tumor (IPMT) treated with resection to determine predictors of prognosis. Between 1989 and 2000, all patients treated with pancreatic resection for IPMT (n = 63) were analyzed. The diagnosis of IPMT was made using the surgical specimen and the World Health Organization definition. Predictors were determined using univariate and multivariate analysis. The pathologic findings were benign (n = 30), carcinoma in situ (CIS; n = 5), and invasive carcinoma (n = 28). After univariate analysis, predictors of malignancy (invasive plus CIS) were jaundice (odds ratio = 10.32), elevated serum CA19-9 (odds ratio = 15.0), any abnormal liver function test (odds ratio = 7.69), and p53 overexpression. The only predictor of benign disease was gross mucus observed during endoscopy (odds ratio = 4.35). After multivariate analysis, predictors of malignancy were any abnormal liver function test (odds ratio = 5.09) and p53 overexpression, whereas the only predictor of benign disease was still gross mucus (odds ratio = 5.88). Actuarial 3- and 5-year survival for benign disease was 95% and 83% and for malignant disease 52% and 44%, respectively (P = 0.0048). Survival curves also favored p53-negative tumors vs. p53-positive tumors (P = 0.0055). In the 33 patients with malignant disease (mean follow-up time = 35 months), the presence of gross mucus was a predictor of prolonged survival after univariate and multivariate analysis (odds ratio = 4.34 and 4.55, respectively), whereas alcohol abuse was a predictor of poor survival (odds ratio = 3.41 and 3.60, respectively). Gross mucus observed during endoscopy is a predictor of benign IPMT and, within the group with malignant IPMT; the presence of gross mucus was associated with better survival. Survival was also strongly associated with either benign IPMT or negative staining for p53 overexpression.

Adenocarcinoma, Mucinous↗
PubMed2003

Use of self-expandable metallic stents in benign GI diseases.

BACKGROUND: The self-expandable metallic stent is of proven benefit in patients with malignant disease; however, its use in patients with benign disease is not well established. There are few data available regarding long-term complications and outcomes with use of self-expandable metallic stents in benign disease and virtually none regarding attempted removal once the acute problem is resolved. METHODS: Thirteen patients who had a self-expandable metallic stent placed for benign GI disorders were included in a retrospective analysis. Data collected included patient demographics, indication for procedure, type of stent used, complications, and patient outcomes. RESULTS: Thirteen patients (7 women, 6 men; mean age 67 years, range 34-84 years) had one or more self-expandable metallic stents placed for benign disease and were followed for a mean of 3.4 years (3 weeks to 10 years). Of the 13 patients, 8 had esophageal stents, 4 biliary stents, and 1 had dual stents placed in the pancreaticobiliary tree. Complications developed in 8 (62%) patients; 4 (31%) ultimately died, either from the primary disease process (3) or from stent-related complications (1). CONCLUSIONS: Self-expandable metallic stent placement is effective treatment for benign esophageal leaks, providing the stent can be removed. It also may be used in either the esophagus or biliary tree in patients who are poor candidates for surgery and short expected survival. However, a self-expandable metallic stent should not be placed in a patient with a benign GI disorder who has a significant life expectancy and is a good candidate for surgery.

Adult↗
PubMed2002

Contamination of single-use biopsy forceps: a prospective in vitro analysis.

BACKGROUND: It has been suggested that single-use biopsy forceps prevent interpatient transmission of infection during endoscopy. Passage of sterile forceps through the accessory channel of the endoscope may lead to contamination, however, if the endoscope has been inadequately processed. The potential for contamination of single-use biopsy forceps at various stages of endoscope reprocessing was prospectively evaluated. METHODS: A total of 50 disposable biopsy forceps were passed through the accessory channels of 10 colonoscopes at the following stages of reprocessing: (1) before use in patients to establish a baseline of high-level disinfection, (2) directly after colonoscopy to confirm contamination with use, (3) after manual cleaning and flushing of the accessory channel to support the claim that manual cleaning significantly decreases bioburden, (4) after manual cleaning and a 2-minute soak in 2% glutaraldehyde to assess for contamination after an inadequate cleaning time, and (5) after manual cleaning and a 20-minute soak in 2% glutaraldehyde. The forceps were then sealed in sterile plastic bags after adding 20 mL of thioglycollate broth medium. The suspension was passed through a 0.2-micron vacuum filter and the filters were cultured. All cultures were incubated more than 48 hours. RESULTS: Biopsy forceps underwent a total of 50 aerobic and 50 anaerobic cultures. Colony-forming units too numerous to count of GI flora, including Escherichia coli, Klebsiella, Pseudomonas, and Clostridium species, grew on 19 of 20 culture plates from biopsy forceps passed through colonoscopes immediately after use. One plate in this group grew 3 colony-forming units of E coli. Persistence of GI flora was noted on 5 of 20 plates after manual cleaning of the colonoscopes. No GI flora were found on forceps after the colonoscopes after soaking in gluteraldehyde for 2 and 20 minutes. Environmental contaminants including diptheroids, Staphylococcus, and Streptococcus species grew on 16 culture plates. CONCLUSIONS: (1) Single-use biopsy forceps are highly susceptible to contamination during passage through the accessory channels of improperly cleaned endoscopes. (2) Disinfection of the colonoscopes in this study prevented contamination of the forceps at baseline and after reprocessing. (3) Proper endoscope reprocessing may be the most important factor in preventing biopsy forceps-related interpatient infection.

Bacteria↗