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A. J. Mao, X.-J. Pan, IV, I. McIlraith, C. M. L. Hutnik; Development of a Prediction Rule to Estimate the Probability of Acceptable Intraocular Pressure Reduction After Selective Laser Trabeculoplasty in Ocular Hypertension and Open-Angle Glaucoma. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3978.
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To develop and validate a prediction rule to estimate the probability of acceptable intraocular pressure reduction after selective laser trabeculoplasty in ocular hypertension and open-angle glaucoma.
Retrospective observational case series.The study population was derived from a cohort of 220 patients with ocular hypertension, open-angle glaucoma, or normal tension glaucoma. Patients were either treatment naïve, intolerant of, or failing medical therapy.Logistic multivariate regression modeling was performed. The diagnostic performance of the prediction rule based on the predictors identified in the multivariate model was validated using the area under receiver operator characteristic curves, calibration and cross validation. An intraocular pressure matrix of acceptable intraocular pressure reduction following selective laser trabeculoplasty was constructed to provide practical assistance in clinical management of open angle glaucoma. A ≥ 20% reduction in IOP from the baseline IOP at 6 months after SLT was considered acceptable IOP reduction and treatment success.
In multivariate logistic regression analyses, pre-SLT IOP and maximum IOP were identified as independent predictors for ≥ 20% IOP reduction at 6 months.The adjusted odds for ≥ 20% IOP reduction corresponding to 1 mmHg increase in pre-SLT IOP and max IOP was 1.3 (95% CI 1.2 to 1.4; p<0.0001) and 0.9 (95% CI 0.9 to 1.0; p=0.0221) respectively, controlling for gender, diagnosis, pigment of anterior chamber and washout of eye drops. The area under receiver operator characteristic curve was 0.716. Calibration of this prediction rule showed good agreement between predicted and observed probabilities of acceptable IOP reduction. If a probability of acceptable IOP reduction of ≥80% is used as the minimal clinical threshold for treatment, the prediction rule had a sensitivity, specificity and positive predictive value of 25.4%, 93.5% and 88% respectively.
SLT efficacy is positively associated with IOP elevation prior to laser treatment and adversely associated with the maximum IOP ever recorded in history. Pigmentation of the anterior chamber angle is not associated with SLT treatment efficacy. The use of NSAID compared with steroid after SLT has a beneficial but non-significant effect on IOP reduction. This prediction rule should be further validated with a comparable prospective clinical study cohort.
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