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.

THE INCIDENCE AND RISK FACTORS FOR INTRA-OPERATIVE HYPOTHERMIA AMONG PAEDIATRIC PATIENTS UNDERGOING GENERAL ANAESTHESIA AT THE KENYATTA NATIONAL HOSPITAL

OBJECTIVE

To determine the incidence and risk factors for intra-operative hypothermia in paediatric patients undergoing general anaesthesia at the Kenyatta National Hospital.

DESIGN

A prospective observational study.

SETTING

The Kenyatta National Hospital main operating theatres and affiliated satellite operating theatres.

SUBJECTS

A total of 100 paediatric patients (range; three days to 12 years, mean; 4.1 ± 3.3 years) were enrolled in the study.

RESULTS

Thirty out of 100 patients developed hypothermia defined as a core temperature < 36 °C recorded at least once during provision of general anaesthesia. Ninety percent of those developing hypothermia were male compared to 63% who remained normothermic (p = 0.006). Proportionally, more than twice as many hypothermic patients had a caudal block (43% versus 20%, p = 0.016) and received 121 ml more of fluid (p = 0.002) compared to the normothermic group. The patients who became hypothermic tended to be colder at induction of anaesthesia (36.6 ± 0.5°C versus 37.0 ± 0.5 °C, p = < 0.0001) but there was no significant difference in the waiting time, time of induction, environmental temperatures or theatre temperatures compared to those not developing hypothermia. There was no significant difference in the BMI between the two groups (14.0 ± 2.9 kg/ m2 versus 15.2 ± 3.5 kg/m2, p = 0.101).

CONCLUSION

The incidence of intra-operative core hypothermia in paediatric patients undergoing general anaesthesia at the Kenyatta National Hospital is 30%. Gender (male), lower body temperature at induction, use of caudal block and the volume of intravenous fluids infused were significant independent predictors of core hypothermia. The most significant predictor was body temperature at the time of induction of general anaesthesia.

Coma scales for children with severe falciparum malaria

The Blantyre coma scale (BCS) is used to assess children with severe falciparum malaria, particularly as a criterion for cerebral malaria, but it has not been formally validated. We compared the BCS to the Adelaide coma scale (ACS), for Kenyan children with severe malaria. We examined the inter-observer agreement between 3 observers in the assessment of coma scales on 17 children by measuring the proportion of agreement (PA), disagreement rate (DR) and fixed sample size kappa (kappa n). We assessed the sensitivity and specificity of the scales in detecting events (seizures and hypoglycaemia) in 240 children during admission and the usefulness of the scales in predicting outcome. There was considerable disagreement between observers in the assessment of both scales (BCS: PA = 0.55, DR = 0.09 and kappa n = 0.27; ACS: PA = 0.36, DR = 0.31, and kappa n = 0.31), particularly with the verbal component of the BCS (kappa n = 0.02). Compared to the ACS, the BCS was more specific (0.85 for BCS and 0.80 for ACS), but less sensitive (0.25-0.69 vs. 0.38-0.88 respectively) in detecting events and was a worse predictor of neurological sequelae. The BCS provided a better overall assessment of a child's incapacity from falciparum malaria, but the ACS was more useful in assessing neurological disturbances.