Wright, David M; Azuara-Blanco, Augusto; Cardwell, Chris; Montesano, Giovanni; Crabb, David P; Gazzard, Gus; King, Anthony J; ... GRIP study group; + view all Wright, David M; Azuara-Blanco, Augusto; Cardwell, Chris; Montesano, Giovanni; Crabb, David P; Gazzard, Gus; King, Anthony J; Hernández, Rodolfo; Morgan, James E; Higgins, Bethany; Takwoingi, Yemisi; GRIP study group; - view fewer (2024) Validating and Updating the OHTS-EGPS Model Predicting 5-year Glaucoma Risk among Ocular Hypertension Patients Using Electronic Records. Ophthalmology Glaucoma 10.1016/j.ogla.2024.10.009. (In press).

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Abstract

Objective: To validate and update the Ocular Hypertension Treatment Study-European Glaucoma Prevention Study (OHTS-EGPS) model predicting risk of conversion from ocular hypertension (OHT) to glaucoma using electronic medical records (EMR). // Design: Evaluation and update of a risk prediction algorithm using EMRs and linked visual field (VF) tests. // Participants: Newly diagnosed OHT patients attending hospital glaucoma services in England. Inclusion criteria are as follows: intraocular pressure (IOP) 22 to 32 mmHg (either eye); normal baseline VF test, defined as Glaucoma Hemifield Test (GHT) “within normal range” in a reliable VF test; at least 2 VF tests in total; no significant ocular comorbidities. // Methods: Risk factors are as follows: age, ethnicity, sex, IOP, vertical cup-to-disc ratio, central corneal thickness, VF pattern standard deviation, family history of glaucoma, systemic hypertension, diabetes mellitus, and glaucoma treatment. Glaucoma conversion was defined as 2 consecutive and reliable VF tests with GHT “outside normal limits” and/or need for glaucoma surgery. For validation, the OHTS-EGPS model was applied to predict a patient’s risk of developing glaucoma in 5 years. In the updating stage, the OHTS model was refitted by re-estimating the baseline hazard and regression coefficients. The updated model was cross-validated and several variants were explored. // Main Outcome Measures: Measures of discriminative ability (c-index) and calibration (calibration slope) were calculated and pooled across hospitals using random effects meta-analysis. // Results: From a total of 138 461 patients from 10 hospital glaucoma services in England, 9030 patients with OHT fitted the inclusion criteria. A total of 1530 (16.9%) patients converted to glaucoma during this follow-up period. The OHTS-EGPS model provided a pooled c-index of 0.61 (95% confidence interval: 0.60–0.63), ranging from 0.55 to 0.67 between hospitals. The pooled calibration slope was 0.45 (0.38–0.51), ranging from 0.25 to 0.64 among hospitals. The overall refitted model performed better than the OHTS-EGPS model, with a pooled c-index of 0.67 (0.65–0.69), ranging from 0.65 to 0.75 between hospitals. // Conclusions: We performed an external validation of the OHTS-EGPS model in a large English population. Refitting the model achieved modest improvements in performance. Given the poor performance of the OHTS-EGPS model in our population, one should use caution in its application to populations that differ from those in the OHTS and EGPS. // Financial Disclosure(s) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

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