Estimation of conditional and marginal odds ratios using the prognostic score

• Published in: Statistics in medicine Vol. 36; no. 4; pp. 687 - 716
• Main Authors: Hajage, David, De Rycke, Yann, Chauvet, Guillaume, Tubach, Florence
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 20.02.2017; Wiley Subscription Services, Inc; Wiley-Blackwell
• Subjects: Adolescent; Adult; Anti-Asthmatic Agents - therapeutic use; Asthma - diagnosis; Asthma - drug therapy; causal inference; Computer Science; confounding; Cost-Benefit Analysis; Estimating techniques; Female; Humans; Logic in Computer Science; Male; Mathematics; Medical prognosis; Medical treatment; Monte Carlo Method; Monte Carlo simulation; Multivariate Analysis; Observational Studies as Topic; observational study; Odds Ratio; Performance evaluation; Prognosis; prognostic score; Propensity Score; Prospective Studies; Regression analysis; Statistics; Statistics as Topic; Treatment Outcome; Young Adult; prognostic score; confounding; causal inference; observational study; propensity score
• ISSN: 0277-6715; 1097-0258; 1097-0258
• DOI: 10.1002/sim.7170

Introduced by Hansen in 2008, the prognostic score (PGS) has been presented as ‘the prognostic analogue of the propensity score’ (PPS). PPS‐based methods are intended to estimate marginal effects. Most previous studies evaluated the performance of existing PGS‐based methods (adjustment, stratification and matching using the PGS) in situations in which the theoretical conditional and marginal effects are equal (i.e., collapsible situations). To support the use of PGS framework as an alternative to the PPS framework, applied researchers must have reliable information about the type of treatment effect estimated by each method. We propose four new PGS‐based methods, each developed to estimate a specific type of treatment effect. We evaluated the ability of existing and new PGS‐based methods to estimate the conditional treatment effect (CTE), the (marginal) average treatment effect on the whole population (ATE), and the (marginal) average treatment effect on the treated population (ATT), when the odds ratio (a non‐collapsible estimator) is the measure of interest. The performance of PGS‐based methods was assessed by Monte Carlo simulations and compared with PPS‐based methods and multivariate regression analysis. Existing PGS‐based methods did not allow for estimating the ATE and showed unacceptable performance when the proportion of exposed subjects was large. When estimating marginal effects, PPS‐based methods were too conservative, whereas the new PGS‐based methods performed better with low prevalence of exposure, and had coverages closer to the nominal value. When estimating CTE, the new PGS‐based methods performed as well as traditional multivariate regression. Copyright © 2016 John Wiley & Sons, Ltd.