Lower ocular pulse amplitude with dynamic contour tonometry is associated with biopsy-proven giant cell arteritis

Objectives: To determine the role of the ocular pulse amplitude (OPA) from Pascal dynamic contour tonometry in predicting the temporal artery biopsy (TABx) result in patients with suspected giant cell arteritis (GCA). Design: Prospective validation study. Participants: Adults aged 50 years or older who underwent TABx from March 2015 to April 2017. Methods: Subjects on high-dose glucocorticoids more than 14 days or without serology before glucocorticoid initiation were excluded. The OPA from both eyes was obtained and averaged just before TABx of the predominantly symptomatic side. The variables chosen for the a priori prediction model were age, average OPA, and C-reactive protein (CRP). Erythrocyte sedimentation rate (ESR), platelets, jaw claudication, and eye findings were also recorded. In this study, subjects with a negative biopsy were considered not to have GCA, and contralateral biopsy was performed if the clinical suspicion for GCA remained high. An external validation set (XVAL) was obtained. Results: Of 109 TABx, 19 were positive and 90 were negative. On univariate logistic regression, the average OPA had 0.60 odds for positive TABx (p = 0.03), with no statistically significant difference in age, sex, CRP, ESR, or jaw claudication. In suspected GCA, an OPA of 1 mm Hg had positive likelihood ratio 4.74 and negative likelihood ratio 0.87 for positive TABx. Multivariate regression of the prediction model using optimal mathematical transforms (inverse OPA, log CRP, age >65 years) had area under the receiver operating characteristic curve (AUROC) = 0.85 and AUROC(xvAL) = 0.81. Conclusions: OPA is lower in subjects with biopsy -proven GCA and is a statistically significant predictor of GCA.