Validation of a Risk Stratification Index and Risk Quantification Index for Predicting Patient Outcomes: In-hospital Mortality, 30-day Mortality, 1-year Mortality, and Length-of-stay
ABSTRACT External validation of published risk stratification models is essential to determine their generalizability. This study evaluates the performance of the Risk Stratification Indices (RSIs) and 30-day mortality Risk Quantification Index (RQI).
108,423 adult hospital admissions with anesthetics were identified (2006–2011). RSIs for mortality and length-of-stay endpoints were calculated using published methodology. 91,128 adult, noncardiac inpatient surgeries were identified with administrative data required for RQI calculation.
RSI in-hospital mortality and RQI 30-day mortality Brier scores were 0.308 and 0.017, respectively. RSI discrimination, by area under the receiver operating curves, was excellent at 0.966 (95% CI, 0.963–0.970) for in-hospital mortality, 0.903 (0.896–0.909) for 30-day mortality, 0.866 (0.861–0.870) for 1-yr mortality, and 0.884 (0.882–0.886) for length-of-stay. RSI calibration, however, was poor overall (17% predicted in-hospital mortality vs. 1.5% observed after inclusion of the regression constant) as demonstrated by calibration plots. Removal of self-fulfilling diagnosis and procedure codes (20,001 of 108,423; 20%) yielded similar results. RQIs were calculated for only 62,640 of 91,128 patients (68.7%) due to unmatched procedure codes. Patients with unmatched codes were younger, had higher American Society of Anesthesiologists physical status and 30-day mortality. The area under the receiver operating curve for 30-day mortality RQI was 0.888 (0.879–0.897). The model also demonstrated good calibration. Performance of a restricted index, Procedure Severity Score + American Society of Anesthesiologists physical status, performed as well as the original RQI model (age + American Society of Anesthesiologists + Procedure Severity Score).
Although the RSIs demonstrated excellent discrimination, poor calibration limits their generalizability. The 30-day mortality RQI performed well with age providing a limited contribution.
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ABSTRACT: This review of progress toward reliable prediction of postoperative pulmonary complications (PPCs) discusses risk assessment against the background of patient management strategies, clinical outcomes, and cost of healthcare. Among the variety of conditions grouped as PPCs are pneumonia, aspiration pneumonitis, respiratory failure, reintubation within 48 h, weaning failure, pleural effusion, atelectasis, bronchospasm, and pneumothorax. PPC incidence rates range from 2 to 40% depending on context. These events increase mortality, postoperative length of stay, ICU admissions, hospital readmissions, and costs. PPC-associated mortality varies, but can reach as high as 48% in some contexts. ICU admission rates are between 9.5 and 91% higher in patients with PPCs. The mean increase in PPC-related postoperative length of stay is approximately 8 days. The cost of surgery can be two-fold to 12-fold higher when PPCs develop. Strategies proposed to reduce the impact of modifiable risk factors include alcohol and smoking abstinence before surgery, shortening the duration of surgery, and physiotherapy and incentive spirometry techniques; however, little scientific evidence supports them at this time. PPCs are associated with a higher incidence of life-threatening events and higher costs. Reliable PPC risk-stratification tools are essential for guiding clinical decision-making in the perioperative period. The care team can act on modifiable factors and optimize vigilance over nonmodifiable ones. It would be useful to focus resources on determining whether low-cost preemptive interventions improve outcomes satisfactorily or new strategies need to be developed.Current opinion in anaesthesiology 01/2014; DOI:10.1097/ACO.0000000000000045 · 2.53 Impact Factor