The effect of etidronate on choroidal neovascular activity in patients with pseudoxanthoma elasticum.

• Main Authors: Sara Risseeuw, Redmer van Leeuwen, Saskia M Imhof, Pim A de Jong, Willem P Th M Mali, Wilko Spiering, Jeannette Ossewaarde-van Norel
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2020-01-01
• Series: PLoS ONE
• Online Access: https://doi.org/10.1371/journal.pone.0240970

<h4>Aim</h4>To assess the effect of the bisphosphonate etidronate on choroidal neovascular (CNV) activity in patients with pseudoxanthoma elasticum (PXE).<h4>Methods</h4>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.<h4>Results</h4>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).<h4>Conclusion</h4>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.