Prediction models for the mortality risk in chronic dialysis patients: a systematic review and independent external validation study
Received 15 April 2017
Accepted for publication 17 July 2017
Published 5 September 2017 Volume 2017:9 Pages 451—464
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Professor Vera Ehrenstein
Chava L Ramspek,1 Pauline WM Voskamp,1 Frans J van Ittersum,2 Raymond T Krediet,3 Friedo W Dekker,1 Merel van Diepen1
On behalf of the NECOSAD study group
1Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, 2Department of Nephrology, VU University Medical Center, 3Department of Nephrology, Academic Medical Center, Amsterdam, The Netherlands
Objective: In medicine, many more prediction models have been developed than are implemented or used in clinical practice. These models cannot be recommended for clinical use before external validity is established. Though various models to predict mortality in dialysis patients have been published, very few have been validated and none are used in routine clinical practice. The aim of the current study was to identify existing models for predicting mortality in dialysis patients through a review and subsequently to externally validate these models in the same large independent patient cohort, in order to assess and compare their predictive capacities.
Methods: A systematic review was performed following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. To account for missing data, multiple imputation was performed. The original prediction formulae were extracted from selected studies. The probability of death per model was calculated for each individual within the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD). The predictive performance of the models was assessed based on their discrimination and calibration.
Results: In total, 16 articles were included in the systematic review. External validation was performed in 1,943 dialysis patients from NECOSAD for a total of seven models. The models performed moderately to well in terms of discrimination, with C-statistics ranging from 0.710 (interquartile range 0.708–0.711) to 0.752 (interquartile range 0.750–0.753) for a time frame of 1 year. According to the calibration, most models overestimated the probability of death.
Conclusion: Overall, the performance of the models was poorer in the external validation than in the original population, affirming the importance of external validation. Floege et al’s models showed the highest predictive performance. The present study is a step forward in the use of a prediction model as a useful tool for nephrologists, using evidence-based medicine that combines individual clinical expertise, patients’ choices, and the best available external evidence.
Keywords: external validation, prediction, nephrology, dialysis, mortality
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