External validation of the OHTS-EGPS model for predicting the 5-year risk of open-angle glaucoma in ocular hypertensives

Yemisi Takwoingi, Adriana P Botello, Jennifer M Burr, Augusto Azuara-Blanco, David F Garway-Heath, Hans G Lemij, Roshini Sanders, Anthony J King, Jonathan J Deeks,

Research output: Contribution to journalArticleResearchpeer-review


AIMS: To independently evaluate and compare the performance of the Ocular Hypertension Treatment Study-European Glaucoma Prevention Study (OHTS-EGPS) prediction equation for estimating the 5-year risk of open-angle glaucoma (OAG) in four cohorts of adults with ocular hypertension.

METHODS: Data from two randomised controlled trials and two observational studies were analysed individually to assess transferability of the prediction equation between different geographical locations and settings. To make best use of the data and to avoid bias, missing predictor values were imputed using multivariate imputation by chained equations. Using the OHTS-EGPS risk prediction equation, predicted risk was calculated for each patient in each cohort. We used the c-index, calibration plot and calibration slope to evaluate predictive ability of the equation.

RESULTS: Analyses were based on 393, 298, 188 and 159 patients for the Rotterdam, Moorfields, Dunfermline, and Nottingham cohorts, respectively. The discriminative ability was good, with c-indices between 0.69 and 0.83. In calibration analyses, the risk of OAG was generally overestimated, although for the Rotterdam cohort the calibration slope was close to 1 (1.09, 95% CI 0.72 to 1.46), the ideal value when there is perfect agreement between predicted and observed risks.

CONCLUSIONS: The OHTS-EGPS risk prediction equation has predictive utility, but further validation in a population-based setting is needed.

Original languageEnglish
Pages (from-to)309-14
Number of pages6
JournalBritish Journal of Ophthalmology
Issue number3
Publication statusPublished - Mar 2014


  • Antihypertensive Agents
  • Female
  • Glaucoma, Open-Angle/diagnosis
  • Humans
  • Intraocular Pressure/physiology
  • Male
  • Middle Aged
  • Observational Studies as Topic
  • Ocular Hypertension/complications
  • Proportional Hazards Models
  • Randomized Controlled Trials as Topic
  • Risk Assessment
  • Risk Factors
  • Tonometry, Ocular


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