Appraising prediction research: a guide and meta-review on bias and applicability assessment using the Prediction model Risk Of Bias ASsessment Tool (PROBAST).

Over the past few years, a large number of prediction models have been published, often of poor methodological quality. Seemingly objective and straightforward, prediction models provide a risk estimate for the outcome of interest, usually based on readily available clinical information. Yet, using models of substandard methodological rigour, especially without external validation, may result in incorrect risk estimates and consequently misclassification. To assess and combat bias in prediction research the prediction model risk of bias assessment tool (PROBAST) was published in 2019. This risk of bias (ROB) tool includes four domains and 20 signalling questions highlighting methodological flaws, and provides guidance in assessing the applicability of the model. In this paper, the PROBAST will be discussed, along with an in-depth review of two commonly encountered pitfalls in prediction modelling that may induce bias: overfitting and composite endpoints. We illustrate the prevalence of potential bias in prediction models with a meta-review of 50 systematic reviews that used the PROBAST to appraise their included studies, thus including 1510 different studies on 2104 prediction models. All domains showed an unclear or high ROB; these results were markedly stable over time, highlighting the urgent need for attention on bias in prediction research. This article aims to do just that by providing (1) the clinician with tools to evaluate the (methodological) quality of a clinical prediction model, (2) the researcher working on a review with methods to appraise the included models, and (3) the researcher developing a model with suggestions to improve model quality.

DIALysis or not: Outcomes in older kidney patients with GerIatriC Assessment (DIALOGICA): rationale and design.

BACKGROUND: The incidence and prevalence of older patients with kidney failure who are dependent on dialysis is increasing. However, observational studies showed limited or no benefit of dialysis on mortality in subgroups of these patients when compared to conservative care. As the focus is shifting towards health-related quality of life (HRQoL), current evidence of effects of conservative care or dialysis on HRQoL in older patients is both limited and biased. Dialysis comes with both high treatment burden for patients and high costs for society; better identification of patients who might not benefit from dialysis could result in significant cost savings. The aim of this prospective study is to compare HRQoL, clinical outcomes, and costs between conservative care and dialysis in older patients. METHODS: The DIALysis or not: Outcomes in older kidney patients with GerIatriC Assessment (DIALOGICA) study is a prospective, observational cohort study that started in February 2020. It aims to include 1500 patients from 25 Dutch and Belgian centres. Patients aged ≥70 years with an eGFR of 10-15 mL/min/1.73m2 are enrolled in the first stage of the study. When dialysis is initiated or eGFR drops to 10 mL/min/1.73m2 or lower, the second stage of the study commences. In both stages nephrogeriatric assessments will be performed annually, consisting of questionnaires and tests to assess most common geriatric domains, i.e. functional, psychological, somatic, and social status. The primary outcome is HRQoL, measured with the Twelve-item Short-Form Health Survey. Secondary outcomes are clinical outcomes (mortality, hospitalisation, functional status, cognitive functioning, frailty), cost-effectiveness, and decisional regret. All outcomes are (repeated) measures during the first year of the second stage. The total follow-up will be a maximum of 4 years with a minimum of 1 year in the second stage. DISCUSSION: By generating more insight in the effects of conservative care and dialysis on HRQoL, clinical outcomes, and costs, findings of this study will help patients and physicians make a shared decision on the best individual treatment option for kidney failure. TRIAL REGISTRATION: The study was registered in the Netherlands Trial Register ( NL-8352 ) on 5 February 2020.