The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications.

BACKGROUND: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. METHODS: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. RESULTS: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. CONCLUSIONS: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. CLINICAL TRIAL REGISTRATION: NCT03044899.

Quantification of collagen synthesis by cultured human glomerular cells.

This study examines the amount of total collagen and its different fractions synthesized by cultured human glomerular epithelial and mesangial cells. Two quantitative techniques were used, namely estimation of proline (Pro) plus hydroxyproline (Hyp) present in the collagenase-sensitive proteins and ELISA or RIA of the different types of collagen. In addition, the pattern of collagen synthesis for both cell types was further examined using immunofluorescence methods and polyacrylamide gel electrophoresis. Glomerular epithelial cells synthesized mainly type IV collagen and it was, for the better part, cell-associated. Mesangial cells synthesized approx. 4-times more collagen than epithelial cells. Type I collagen was predominant, but there were also type IV and III collagens. Secreted and cell-associated collagens were present in roughly equivalent amounts. In both cell lines 10-14% of the newly synthesized collagen had been degraded within the cells. These results provide quantitative data on collagen synthesis by human glomerular cells in vitro and represent the first necessary stage before studying which factors mediate the development of glomerular sclerosis.