The purpose of the study «Brandt JD, Gordon MO, Gao F ym. Adjusting intraocu...»1 was to determine if the accuracy of the baseline prediction model for the development of primary open angle glaucoma (POAG) in patients with ocular hypertension (OHT) can be improved by correcting intra ocular pressure (IOP) for central corneal thickness (CCT).
Reanalysis of the prediction model for the risk of developing POAG was carried out using the same baseline variables (age, IOP, CCT, VCDR, and PSD) except that IOP was adjusted for CCT using correction formulae. A separate Cox proportional hazards model was run using IOP adjusted for CCT by each of the 5 formulae published to date. Models were run including and excluding CCT.
The material consisted of a total of 1433 of 1636 participants randomized to OHTS who had complete baseline data for factors in the prediction model: age, IOP, CCT, vertical cup-to-disc ratio (VCDR), and pattern standard deviation (PSD).
C-statistics for prediction models that used IOP adjusted for CCT by various formulas ranged from 0.75 to 0.77, no better than the original prediction model (0.77) that did not adjust IOP for CCT.