Abstract
Purpose :
Patient self-reported outcome measures (PROMs) using questionnaires are widely used as primary end points in clinical trials. The UK Glaucoma Treatment Study (UKGTS) demonstrated the effectiveness of an intraocular-pressure-lowering drug in patients with glaucoma using visual field deterioration determined by standard automated perimetry as a primary outcome (Garway-Heath et al 2014 Lancet). We investigate PROMs of glaucoma-related functional impairment as a secondary outcome measure in UKGTS.
Methods :
UKGTS was a multi-centre, randomised, double-masked, placebo-controlled trial, where 516 patients with newly diagnosed open angle glaucoma were allocated to receive latanoprost (intervention group) or placebo (control group) eye drops. Patients completed the 15-item Glaucoma Quality of Life-15 (GQL) questionnaire at the start of the study and at the final visit or exit from the trial. A GQL score was calculated for each patient by summing ordinal responses and transposing to a percentage, with 100% meaning a person has severe difficulty with all 15 functional items. Proportion of patients in the intervention and study group, following an intention to treat protocol, reporting a 15% worsening (conservative criteria) and a 5% worsening (sensitive criteria) in this GQL score were calculated and assessed using Fisher’s Exact Test. Mean score change was also calculated for both groups with EQ5D health states and age examined as covariate
Results :
Of 461 patients with post-baseline visits, complete GQL questionnaires were available for 182 from the treated group and 168 controls. Fourteen treated (7.7%) and 15 control (8.9%) patients met conservative criteria in GQL score change, indicating no statistically significant difference (p=0.70). No statistically significant difference between groups using the sensitive criteria (29.8% treated versus 30.8% controls; p=0.24) were evident. Mean worsening in GQL score was not different between groups (2.7 (SD:7.7)% in treated versus 3.2 (SD:11.7)% in controls; two-sample t-test; p=0.72). Differences remained statistically not significant after adjusting for age and responses to EQ5D health states.
Conclusions :
Change in GQL scores from baseline was similar in patients in the intervention and control group in UKGTS. PROMs may not be sensitive enough to be used as endpoints in glaucoma clinical trials.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.