| Institution: | 1. Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Japan;2. Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Republic of Korea;3. Center for Medical Education, Sapporo Medical University School of Medicine, Japan;4. Department of Public Health and Hygiene, University of the Ryukyus Graduate School of Medicine, Japan;5. Division of Pulmonary and Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Republic of Korea;6. Department of Respiratory Medicine and Allergy, Tosei General Hospital, Japan;7. Department of Advanced and Integrated Interstitial Lung Diseases Research, School of Medicine, Toho University, Japan;8. Department of Respiratory Medicine, Tokyo Medical and Dental University, Japan;1. University of Michigan Health System, Ann Arbor, MI;2. University of Michigan Department of Biostatistics, Ann Arbor, MI;3. Royal Brompton and Harefield National Health Service Foundation Trust, London, England;4. National Jewish Health, Denver, CO;1. Department of Respiratory Medicine, Kanagawa Cardiovascular and Respiratory Center, Yokohama, Japan;2. Department of Respiratory Medicine, Saitama Red Cross Hospital, Saitama, Japan;3. Department of Biostatistics, Yokohama City University School of Medicine, Yokohama, Japan;1. Department of Respiratory Medicine and Allergology, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan;2. Department of Respiratory Medicine and Allergology, Kindai University Nara Hospital, Ikoma, Nara 630-0293, Japan |
| Abstract: | BackgroundThe easy-to-calculate gender, age, and lung physiology (GAP) model shows good predictive and discriminative performance in the prognosis of idiopathic pulmonary fibrosis (IPF). However, the GAP model was not effective in predicting the prognosis accurately in previous Japanese and Korean IPF cohort studies. Therefore, we developed a modified GAP model for the East-Asian populations by weighing the GAP variables. The validity of the modified GAP model was subsequently evaluated in East-Asian IPF patients.MethodsThe derivation cohort comprised 326 patients with IPF. Weights of the variables were adjusted on the basis of coefficients derived from Cox regression models. The total points were distributed to the three stages of the disease so that the number of patients included in each stage was appropriate. The validity of the modified model was analyzed in another Japanese cohort of 117 patients with IPF and a nationwide cohort of Korean patients with IPF.ResultsPredicted survival rates differed significantly in the derivation cohort using the modified GAP model for each stage of IPF (log-rank test: stage I vs. stage II, p < 0.001; stage II vs. stage III, p < 0.001). Model performance improved according to Harrell's C-index (at three years: 0.696 in the original GAP model to 0.738 in the modified model). The performance of the modified model was validated in the Japanese validation and Korean national cohorts.ConclusionsOur modification of the original GAP model showed improved performance in East-Asian IPF patient populations. |
