COPENHAGEN — For patients with diabetic macular edema, visual acuity at 1 and 3 years is better if central retinal thickness has decreased by at least 20% after three monthly injections of the anti-VEGF ranibizumab, an analysis of the DRCR.net Protocol I data suggests.
"The take-home message is that, after 3 months or three injections, we can predict the long-term outcome of anti-VEGF treatments in the majority of diabetic macular edema patients," said Albert Augustin, MD, from the Staedtisches Klinikum Karlsruhe in Germany.
"This means that a switch in therapy might be necessary if they are less responsive," he told Medscape Medical News.
"This is the first analysis to demonstrate that a signal for long-term central retinal thickness response to anti-VEGF therapy in diabetic macular edema is seen after just three injections," Dr Augustin said here at the European Society of Retina Specialists 16th EURETINA Congress.
For their post hoc analysis, he and his colleagues assessed 335 eyes from the Protocol I dataset (Ophthalmology. 2010;117:1064-1077). The analysis was conducted independent of the DRCR.net Protocol I investigators.
They used optical coherence tomography at 12 weeks to measure change in central retinal thickness from baseline. They assessed anatomic response to anti-VEGF therapy at 1 and 3 years using unadjusted and multivariate analyses.
At 12 weeks, the central retinal thickness of 65% of the 335 eyes had decreased by at least 20% from baseline. These eyes were more likely than the 35% of remaining eyes — those with a central retinal thickness that did not decrease by at least 20% — to show a sustained response to therapy over the long term.
On initial analysis, sex, age, previous treatment, baseline best corrected visual acuity, and 12-week response were significantly different between the group with at least 20% improvement and the less-improved group (P < .05 for all).
On multivariate logistic analysis, the association between change in central retinal thickness and outcomes was confirmed. "After controlling for confounders, we still see a significant association between early — which is 12 weeks — and 52- and 156-week responses," Dr Augustin reported.
Table. Long-term Response by Central Retinal Thickness at 12 Weeks
| Follow-up | ≥20% Improvement, % | <20% Improvement, % | P Value |
| 1 year | 83.9 | 31.4 | <.001 |
| 3 years | 82.9 | 51.7 | <.001 |
"It was a good presentation and the results are very good," said session moderator Jans Keunen, MD, PhD, from the Radboud University Medical Centre in Nijmegen, the Netherlands.
"It's very convincing to me," he told Medscape Medical News.
"The message is important — you can already see which patients will do well" early on. "Otherwise," he pointed out, "it usually takes half a year or 9 months to assess response."
Gauging treatment response earlier is also critical for cost-effective care, Dr Keunen explained. "In the Netherlands, we are looking for these data as ophthalmologists."
After the presentation, a member of the audience asked whether agents should be switched after three injections if treatment does not sufficiently reduce central retinal thickness.
"I think there is a big debate," Dr Augustin replied. "Maybe after somewhere between three and six injections we should switch, because obviously those patients have no further benefit."
Dr Augustin reports receiving speaker honoraria, travel support, and study grants from Allergan. Dr Keunen has disclosed no relevant financial relationships.
European Society of Retina Specialists 16th EURETINA Congress. Presented September 10, 2016.
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Cite this: Predicting Anti-VEGF Response in Diabetic Macular Edema - Medscape - Sep 13, 2016.
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