Predicting ADR from PDR and individual adenoma-to-polyp-detection-rate ratio for screening and surveillance colonoscopies: A new approach to quality assessment.

BACKGROUND AND AIMS: Adenoma detection rate (ADR) has been established as a quality indicator for screening colonoscopy. Because ADR is cumbersome to obtain in routine practice, polyp detection rate (PDR), polypectomy rate (PR) and adenoma-to-polyp-detection-rate-ratio (APDRR) have been proposed to estimate ADR. This study aimed to evaluate APDRR in order to estimate ADR (ADRest) in different settings. METHODS: Average risk screening and surveillance colonoscopies from a community-based private practice and a tertiary academic hospital setting were retrospectively evaluated. APDRR was calculated as averaged group APDRR for all study procedures (APDRR) and for the first half of study procedures of each gastroenterologist (APDRRag) or individually for each gastroenterologist on the basis of his or her first 25, 50 and 100 colonoscopies (APDRRind). ADRest was determined from PDR by using APDRR, APDRRag, and APDRRind, respectively. RESULTS: A total of 2717 individuals were analyzed. Using APDRR, significant correlations between ADR and ADRest were observed for the entire (0.944, p < 0.001), proximal (0.854, p < 0.001), and distal (0.977, p < 0.001) colon. These correlations were lost when APDRRag was used to estimate each gastroenterologist's ADR for the second half of his or her included colonoscopies. However, ADR and ADRest correlated significantly with a root-mean-square-error of 6.8% and 5.8% when APDRRind on the basis of each gastroenterologist's first 50 and 100 colonoscopies was used for subsequent colonoscopies. CONCLUSIONS: ADR for subsequent colonoscopies of an individual endoscopist can be reliably estimated from PDR by using an individually calculated APDRR. Prospective studies are needed to verify this promising approach in different practice settings.

Inhibition of nitric oxide synthesis improves detoxication in inflammatory liver dysfunction in vivo.

Inflammatory stimulation of the liver induces nitric oxide (NO) biosynthesis and suppression of detoxication. In this study the effect of NO biosynthesis on cytochrome P-450 (CYP) enzyme activity was investigated by comparing in vivo and in vitro assays. To establish liver inflammation, CD rats were injected with Corynebacterium parvum (C. parvum) suspension. After 5 days NO biosynthesis was highly induced as indicated by increased NO2- plus NO3- serum concentrations. At the same time the aminopyrine breath test (ABT), measuring CYP activity in vivo, was reduced to 42% and the in vitro assay of aminopyrine turnover was suppressed to 12% of NaCl- injected controls. When C. parvum-injected animals were treated with the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA), CYP activities significantly improved with an ABT of 76% and an in vitro aminopyrine turnover of 47% of controls. Neither C. parvum injections nor L-NMMA treatment resulted in a significant change of CYP protein concentrations. These data indicate that suppression of xenobiotic metabolism can be attenuated by inhibition of NO biosynthesis during an ongoing process of inflammation.