50849
document
Adjusting intraocular pressure for central corneal thickness does not improve prediction models for primary open-angle glaucoma . PURPOSE To determine if the accuracy of the baseline prediction model for the development of primary open-angle glaucoma ( POAG ) in patients with ocular hypertension can be improved by correcting intraocular pressure ( IOP ) for central corneal thickness ( CCT ) . DESIGN Reanalysis of the baseline prediction model for the development of POAG from the Ocular Hypertension Treatment Study ( OHTS ) substituting IOP adjusted for CCT using 5 different correction formulae for unadjusted IOP . PARTICIPANTS 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 ) . METHODS Reanalysis of the prediction model for the risk of developing POAG 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 . MAIN OUTCOME MEASURES Predictive accuracy of each Cox proportional hazards model was assessed using the c-statistic and calibration chi-square . RESULTS 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 . Calibration chi-square was acceptable for all models . Baseline IOP , whether adjusted for CCT or not , was statistically significant in all models including those with CCT in the same model . The CCT was statistically significant in all models including those with IOP adjusted for CCT in the same model . CONCLUSIONS The calculation of individual risk for developing POAG in ocular hypertensive individuals is simpler and equally accurate using IOP and CCT as measured , rather than applying an adjustment formula to correct IOP for CCT .
50850
Intervention_Other
baseline prediction model
50851
Intervention_Other
prediction
50852
Outcome_Other
Predictive accuracy of each Cox proportional hazards model
50853
Outcome_Other
the c-statistic and calibration chi-square
50854
Outcome_Physical
Baseline IOP
50855
Outcome_Physical
CCT
50856
Participant_Condition
ocular hypertension
50857
Participant_Sample-size
1433
50858
Participant_Sample-size
1636
50859
Participant_Condition
OHTS
50860
Participant_Condition
ocular hypertensive