The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

Holliday junction binding and processing by the RuvA protein of Mycoplasma pneumoniae.

The RuvA, RuvB and RuvC proteins of Escherichia coli act together to process Holliday junctions formed during recombination and DNA repair. RuvA has a well-defined DNA binding surface that is sculptured specifically to accommodate a Holliday junction and allow subsequent loading of RuvB and RuvC. A negatively charged pin projecting from the centre limits binding of linear duplex DNA. The amino-acid sequences forming the pin are highly conserved. However, in certain Mycoplasma and Ureaplasma species the structure is extended by four amino acids and two acidic residues forming a crucial charge barrier are missing. We investigated the significance of these differences by analysing RuvA from Mycoplasma pneumoniae. Gel retardation and surface plasmon resonance assays revealed that this protein binds Holliday junctions and other branched DNA structures in a manner similar to E. coli RuvA. Significantly, it binds duplex DNA more readily. However it does not support branch migration mediated by E. coli RuvB and when bound to junction DNA is unable to provide a platform for stable binding of E. coli RuvC. It also fails to restore radiation resistance to an E. coli ruvA mutant. The data presented suggest that the modified pin region retains the ability to promote junction-specific DNA binding, but acts as a physical obstacle to linear duplex DNA rather than as a charge barrier. They also indicate that such an obstacle may interfere with the binding of a resolvase. Mycoplasma species may therefore process Holliday junctions via uncoupled branch migration and resolution reactions