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Michel Michaelides, Simona Esposti, Ranjan Rajendram, Robin Hamilton, Andrew Kaines, Samantha Fraser-Bell, Cathy Egan, Tunde Peto, Catey Bunce, Phil Hykin; Exploring Parameters That May Be Associated With The Efficacy Of Response To Intravitreal Bevacizumab (ivB) In A Two-year Prospective Randomised Trial Comparing ivB With Laser Therapy In The Management Of Diabetic Macular Oedema (BOLT Study). Invest. Ophthalmol. Vis. Sci. 2011;52(14):5334.
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To explore whether parameters can be identified in the BOLT study that help to predict which patients are most likely to benefit from intravitreal therapy.
Bevacizumab-treated patients were investigated at the 12 (n=42) and 24 (n=37) month time points. Patients were divided into "Good Responders" and "Bad Responders". Analysis was undertaken using two definitions of good response: i) > 15 letters gained, and ii) > 10 letters gained at each of the aforementioned time points. The baseline parameters that were compared included: 1. sex; 2. age; 3. duration of oedema; 4. duration of diabetes; 5. HbA1c; 6. number of previous laser treatments; 7. baseline visual acuity; 8. baseline macular perfusion and ETDRS retinopathy severity score; 9. central macular thickness and total macular volume; and 10. optical coherence tomography macular phenotype. We are also analysing the data to establish whether there was a "good response" after 3 or 5 loading injections.
In year 1, 12% of ivB-treated patients gained > 15 letters compared to 32% in year 2; with 31% gaining > 10 letters at 12 months and 49% at 24 months.No statistically significant differences were observed in the aforementioned baseline parameters when comparing between good and bad responders either at the one or two year time points. In particular, it has previously been suggested that the presence of a foveal detachment may indicate a likely poor prognosis. In our small series, 10 patients had a detachment at baseline, with 6 of these subjects going on to gain > 10 or 15 letters at the one and/or two year time points.
Our study is inherently limited due to the relatively small sample size. Nevertheless, we have undertaken this analysis to encourage other colleagues to perform similar assessments in order that meta-analyses may be performed which may identify parameters that could be used to predict response and thereby help select the most appropriate patients for treatment and also establish the threshold for stopping therapy. It is noteworthy that despite the relatively long duration of CSME (median 24 months [18-48]) and multiple previous laser treatments (median 3 [2-4]) prior to ivB, in both the good and bad responders, these were not identified as being significant limiting factors.
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