A risk index for advanced neoplasia on the second surveillance colonoscopy in patients with previous adenomatous polyps.

BACKGROUND: Predicting the risk of advanced colorectal neoplasia on the second surveillance colonoscopy could help tailor surveillance. OBJECTIVE: To derive and validate a risk index for advanced neoplasia on the second surveillance colonoscopy. DESIGN: Retrospective cohort. SETTING: Single-specialty practice; Veterans Affairs Medical Center. PATIENTS: A total of 965 patients with baseline adenomatous polyps, 2 surveillance colonoscopies, and no reported family history of colorectal cancer; validation cohort of 372. INTERVENTIONS: Multivariable logistic regression including demographics and previous colonoscopy results; derivation and validation of a risk index. MAIN OUTCOME MEASUREMENTS: Advanced adenoma (≥1 cm in size, villous histology, or high-grade dysplasia) on the second surveillance colonoscopy. RESULTS: Mean age was 57.8 ± 9.8 years, 62% were men, and 36% had an advanced adenoma on the index colonoscopy. Associated with advanced adenoma on the second surveillance colonoscopy were age at index colonoscopy (scored 0 for younger than 55 years of age, 1 for 55-59 years of age, 2 for 60-64 years of age, and 3 for older than 65 years of age) and previous findings (non-neoplastic, nonadvanced, advanced [scored 0, 1, and 2, respectively]) on index colonoscopy and the first surveillance colonoscopy, with scores ranging from 1 to 7. Risks of advanced adenoma on the second surveillance colonoscopy with scores of 5 or less and more than 5 were 4.8% (95% confidence interval, 3.5%-6.4%) and 14.9% (95% confidence interval, 7.4%-25.7%), respectively, comprising 93% and 7%, respectively, of the cohort. Corresponding results in the validation cohort were 5.6% and 19.2%, respectively, comprising 86.1% and 13.9%, respectively, of the cohort. LIMITATIONS: Retrospective study with potential for selection bias. CONCLUSION: This index stratifies the risk of advanced adenoma on the second surveillance colonoscopy. If validated independently, it may be useful for tailoring surveillance.

Clinical application of polymerase chain reaction to diagnose Clostridium difficile in hospitalized patients with diarrhea.

BACKGROUND & AIMS: Clostridium difficile is a common cause of diarrhea in hospitalized patients and is associated with significant morbidity and cost. The current diagnostic standard, enzyme immunoassay (EIA), has low sensitivity, leading to duplicate testing and empiric treatment. We sought to show the usefulness and potential cost effectiveness of polymerase chain reaction (PCR) amplification of toxin B gene for diagnosis of C. difficile-induced diarrhea. METHODS: A total of 148 stool samples from academic and community-based hospitals were sent for EIA testing and were evaluated prospectively for the presence of toxin B gene by PCR. Results were compared with EIA regarding sensitivity, specificity, and predictive values. Medical charts were reviewed to determine the following: (1) number of EIAs sent per admission, (2) number sent within a 24-hour time period, and (3) how caregivers practiced based on EIA results. RESULTS: The mean age of 130 patients was 55 years. EIA and PCR were positive in 6.8% and 13.6% of patients, respectively. EIA sensitivity was 40%, specificity was 98%, and positive and negative predictive values were 80% and 91%, respectively. The cost of the PCR was $22/sample. Empiric treatment for C. difficile was given unnecessarily in 42% of EIA-negative results. Thirty percent of patients had 3 or more EIAs sent during their hospital admission. Of patients with multiple samples sent, 57% had more than 1 sample sent in a 24-hour period. CONCLUSIONS: Many physicians do not conform to practice guidelines regarding recommended diagnosis and empiric treatment of C. difficile. Toxin B gene PCR represents a more sensitive and potentially cost-effective method to diagnose C. difficile-induced diarrhea than EIA and should be considered for use as an alternative diagnostic standard.