External validation of the SAPS II, APACHE II and APACHE III prognostic models in South England: a multicentre study.

OBJECTIVE: External validation of three prognostic models in adult intensive care patients in South England. DESIGN. Prospective cohort study. SETTING: Seventeen intensive care units (ICU) in the South West Thames Region in South England. PATIENTS AND PARTICIPANTS: Data of 16646 patients were analysed. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: We compared directly the predictive accuracy of three prognostic models (SAPS II, APACHE II and III), using formal tests of calibration and discrimination. The external validation showed a similar pattern for all three models tested: good discrimination, but imperfect calibration. The areas under the receiver operating characteristics (ROC) curves, used to test discrimination, were 0.835 and 0.867 for APACHE II and III, and 0.852 for the SAPS II model. Model calibration was assessed by Lemeshow-Hosmer C-statistics and was Chi(2 )=232.1 for APACHE II, Chi(2 )=443.3 for APACHE III and Chi(2 )=287.5 for SAPS II. CONCLUSIONS: Disparity in case mix, a higher prevalence of outcome events and important unmeasured patient mix factors are possible sources for the decay of the models' predictive accuracy in our population. The lack of generalisability of standard prognostic models requires their validation and re-calibration before they can be applied with confidence to new populations. Customisation of existing models may become an important strategy to obtain authentic information on disease severity, which is a prerequisite for reliably measuring and comparing the quality and cost of intensive care.

Waiting for the break of dawn? The effects of discharge time, discharge TISS scores and discharge facility on hospital mortality after intensive care.

OBJECTIVE: To assess the effects of discharge Therapeutic Intervention Scoring System (TISS) scores, discharge time and type of discharge facility on ultimate hospital mortality after intensive care. DESIGN: Retrospective cohort study. SETTING: General intensive care unit (ICU) in a district general hospital. PATIENTS AND PARTICIPANTS: One thousand six hundred fifty-four ICU patients discharged to hospital wards or high dependency units (HDUs). MAIN MEASUREMENTS AND RESULTS: Vital status at ultimate hospital discharge was the main outcome measurement. The crude hospital mortality after ICU discharge (12.6%) was significantly associated with increasing discharge TISS scores (chi(2) for trend =9.0, p=0.028). This trend was similarly observed after adjusting for severity of disease. Patients with high TISS scores (>30) who were discharged to hospital wards had a higher risk (1.31; CI: 1.02-1.83) of in-hospital death compared with patients discharged to HDUs. Crude mortality was significantly higher for late 20.00 h to 7.59 h) than for early (8.00 h to 19.59 h) discharges (18.8% versus 11.2%, chi(2) =12.1, p=0.0004). Adjusted for disease severity, the mortality risk was 1.70-fold (CI: 1.28-2.25) increased for late ICU discharges. Patients discharged late to hospital wards had significantly higher severity-adjusted risks (1.87; CI:1.36-2.56) than had patients discharged to HDUs (1.35; CI: 0.77-2.36). CONCLUSIONS: Both late discharge and high discharge TISS scores are indicators of "premature" ICU discharge and were associated with increased mortality. Intermediate care reduced the mortality of patients discharged "prematurely" from ICU. This adds to the growing evidence of the benefits of intermediate care after ICU discharge.