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

Measuring ecosystem function: consequences arising from variation in biomass-productivity relationships

Species diversity loss is expected to alter ecosystem function, but previous work has demonstrated inconsistent relationships between these two factors. Productivity is the most common measure of ecosystem function, but given the difficulty in measuring productivity, standing biomass or change in biomass are frequently used as proxy measures. A review of the recent ecosystem-function literature revealed that 93% of studies measure productivity as biomass, thereby assuming a strong positive relationship between these two variables. We tested this assumption by measuring biomass and productivity in seagrass beds in the Gulf of Mexico. We found that the relationship between standing biomass and productivity could be positive or negative, depending on site. Change in biomass over months inconsistently underestimated short-term productivity. The relationship between biomass and productivity may depend on plant age, successional stage, or site-specific rates of tissue loss to herbivory, senescence, or disturbance. Our results suggest that if biomass continues to be used as a measure of productivity without justification, highly productive communities that typically show little change in biomass, such as healthy climax communities, will not be interpreted as such. The conflicting results of previous studies investigating the relationship between diversity and productivity may be due to differences in the inherently variable relationship between biomass and productivity at different sites and scales.C.P. terHorst, and P. Mungui