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The effect of etidronate on choroidal neovascular activity in patients with pseudoxanthoma elasticum
Sara Risseeuw1, Redmer van Leeuwen1, Saskia M Imhof1
1Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
Aim:
To assess the effect of the bisphosphonate etidronate on choroidal neovascular (CNV) activity in patients with pseudoxanthoma elasticum (PXE).
Methods:
This is an ancillary study in a single center, randomized, double-blind placebo-controlled trial (RCT) in which 74 patients with PXE were assigned to either one-year etidronate or placebo treatment. Spectral domain optical coherence tomography (SD-OCT) imaging and color fundus photography were performed every three months for one year and were systematically assessed on signs of CNV activity.
Results:
In the etidronate group, 11 (30%) of the patients had CNV activity at baseline, compared to 25 (67%) of the patients in the placebo group (P = 0.005). The proportion of eyes with CNV activity during the study ranged from 18-33% in the etidronate group and 42-56% in the placebo group and no significant difference in improvement or worsening of CNV activity was found (P = 0.168). Using a generalized mixed model for repeated measures, there was a protective effect of etidronate in crude analysis (RR 0.86, 95% CI 0.75-0.98) that disappeared when adjusting for baseline CNV activity (RR 0.97, 95% CI 0.84-1.13).
Conclusion:
In this post-hoc RCT analysis we did not observe a protecting or deteriorating effect of etidronate on CNV activity in patients with PXE after adjustment for baseline CNV.
