Abstract
The Gender-Age-Physiology (GAP) model is a validated, baseline-risk prediction model for mortality in idiopathic pulmonary fibrosis. Longitudinal variables have been shown to contribute to risk prediction in idiopathic pulmonary fibrosis and may improve the predictive performance of the baseline GAP model. Our aims were to further validate the GAP model and evaluate whether the addition of longitudinal variables improves its predictive performance.
The study population was derived from a large clinical trials cohort of patients with idiopathic pulmonary fibrosis (n=1109). Model performance was determined by improvement in the C-statistic, net reclassification improvement, clinical net reclassification improvement, and a goodness-of-fit test.
The GAP model had good discriminative performance with a C-statistic of 0.757 (95% CI 0.750–0.764). However, the original GAP model tended to overestimate risk in this cohort. A novel, easy to use model, consisting of the original GAP predictors plus history of respiratory hospitalisation and 24-week change in forced vital capacity (the longitudinal GAP model) improved model performance with a C-statistic of 0.785 (95% CI 0.780–0.790), net reclassification improvement of 8.5%, clinical net reclassification improvement of 25%, and a goodness-of-fit test of 0.929.
The Longitudinal GAP model, along with the original GAP model, may unify baseline and longitudinal mortality risk prediction in idiopathic pulmonary fibrosis.
Abstract
GAP and longitudinal GAP models may provide simple unified baseline and longitudinal mortality risk prediction in IPF http://ow.ly/FhYwZ
Footnotes
For editorial comment see Eur Respir J 2015; 45: 1208–1210 [10.1183/09031936.00043915].
This article has supplementary material available from erj.ersjournals.com
Support statement: This study was funded by the University of California, San Francisco Nina Ireland Program for Lung Health and InterMune, Inc.
Conflict of interest: Disclosures can be found alongside the online version of this article at erj.ersjournals.com
- Received August 9, 2014.
- Accepted November 25, 2014.
- Copyright ©ERS 2015