Validation of the Preoperative Score to Predict Postoperative Mortality (POSPOM) in Germany

Abstract

Background The Preoperative Score to Predict Postoperative Mortality (POSPOM) based on preoperatively available data was presented by Le Manach et al. in 2016. This prognostic model considers the kind of surgical procedure, patients' age and 15 defined comorbidities to predict the risk of postoperative in-hospital mortality. Objective of the present study was to validate POSPOM for the German healthcare coding system (G-POSPOM). Methods and findings All cases involving anaesthesia performed at the University Hospital Bonn between 2006 and 2017 were analysed retrospectively. Procedures codified according to the French Groupes Homogènes de Malades (GHM) were translated and adapted to the German Operationen- und Prozedurenschlüssel (OPS). Comorbidities were identified by the documented International Statistical Classification of Diseases (ICD-10) coding. POSPOM was calculated for the analysed patient collective using these data according to the method described by Le Manach et al. Performance of thereby adapted POSPOM was tested using c-statistic, Brier score and a calibration plot. Validation was performed using data from 199,780 surgical cases. With a mean age of 56.33 years (SD 18.59) and a proportion of 49.24% females, the overall cohort had a mean POSPOM value of 18.18 (SD 8.11). There were 4,066 in-hospital deaths, corresponding to an in-hospital mortality rate of 2.04% (95% CI 1.97 to 2.09%) in our sample. POSPOM showed a good performance with a c-statistic of 0.771 and a Brier score of 0.021. Conclusions After adapting POSPOM to the German coding system, we were able to validate the score using patient data of a German university hospital. According to previous demonstration for French patient cohorts, we observed a good correlation of POSPOM with in-hospital mortality. Therefore, further adjustments of POSPOM considering also multicentre and transnational validation should be pursued based on this proof of concept.

The level of postoperative care influences mortality prediction by the POSPOM score: A retrospective cohort analysis

“…Overall mortality in our cohort was slightly increased compared to the weighed mortality reported by the French colleagues. As previously described, the composition of our study population differs from the one described by Le Manach et al, with a general shift towards higher POSPOM scores [ 15 ]. Increased mortality of lower-risk patients in our cohort may be explained by the exclusion of outpatient surgery.…”

“…The remaining 199,258 patients were included in the final analysis ( Fig 1 ). Adaptation of the French POSPOM scoring model to the German coding system was performed as previously described [ 15 ]. The distribution of POSPOM score values across the surgical disciplines as well as the characteristics of patient age and comorbidities are shown in detail in the Supplemental S2 and S3 Tables.…”

“…The work has been reported in line with the STROCSS criteria [ 17 ]. Adaptation of the POSPOM scoring system to the German coding system was performed as previously described [ 15 ]. In brief, all data were extracted from the anonymized electronic database generated as provided by law following the German hospital fees act ( Krankenhausentgeltgesetz [KHEntG]), §21 [ 18 ].…”

“…The POSPOM obtains its predictive power not at least from the remarkable size of the cohort used for its derivation comprising over 2.7 million patients. Its discriminative strength has been successfully demonstrated in patient populations undergoing abdominal, vascular, and orthopedic surgery in countries outside France [ 11 – 15 ].…”

“…We hypothesized that the normalized predicted postoperative mortality according to the POSPOM varies depending on whether patients are transferred either to the normal ward or the ICU following surgery, thus impairing the predictive validity of the score. To test our hypothesis, we used a POSPOM adapted from the French to the German coding system as previously described [ 15 ].…”