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Title: Factors Influencing the Placebo Effect in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension: An Analysis of Two Randomized Clinical Trials
Authors: Kawamura, Taichi
Sato, Izumi  kyouindb  KAKEN_id
Kawakami, Koji  kyouindb  KAKEN_id
Author's alias: 川上, 浩司
Issue Date: 2-Jun-2016
Publisher: Public Library of Science
Journal title: PLOS ONE
Volume: 11
Issue: 6
Thesis number: e0156706
Abstract: Objective: To explore factors related to the placebo effect in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH). Methods: This was a retrospective cohort study of patients with POAG and patients with OH who were treated with placebo. The patients' data were extracted from two randomized, double-masked, parallel, multicenter clinical trials (trial 1 and trial 2) in Japan. We explored the baseline factors that were associated with the intraocular pressure (IOP)-lowering effect of placebo ophthalmic solution after 4 weeks of instillation treatment at two time points by using multivariable models. The time points were Hour 0 (between 08:30 and 10:30 before instillation) and Hour 2 (within 1. 5 to 2. 5 h after instillation and by 12:30) at the baseline date and after 4 weeks. The changes in IOP from baseline to 4 weeks at the two time points were evaluated for the IOP-lowering effect induced by placebo instillation. Results: Of the 330 patients included in the two trials, 89 patients were eligible for the analysis. The results of the multivariable analysis for Hour 0 indicated a high IOP at the baseline date (coefficient: 0. 24, 95% confidence interval (CI): 0. 02 to 0. 46, P = 0. 03), and the magnitude of the IOP fluctuation at the baseline date (coefficient: 0. 57, 95% CI: 0. 24 to 0. 90, P = 0. 001) was associated with the IOP-lowering effect after 4 weeks. With respect to Hour 2, the trial type was associated with the IOP-lowering effect (coefficient: -1. 15, 95% CI: -2. 14 to -0. 16, P = 0. 02). Conclusions: A large fluctuation in IOP during the day is associated with the IOP-lowering effect induced by placebo in patients with POAG or OH. This finding would be helpful to researchers when designing studies related to glaucoma in the early stages of clinical development of drugs.
Rights: © 2016 Kawamura et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DOI(Published Version): 10.1371/journal.pone.0156706
PubMed ID: 27254076
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