Limit Ranibizumab Injections in Macular Degeneration

Neil Osterweil

September 19, 2014

LONDON — The lucky number is 7 — or 7.1 to be exact — the mean optimum number of injections of intravitreal ranibizumab (Lucentis, Genentech) that should be given during the first year of treatment for neovascular age-related macular degeneration, according to a new meta-analysis.

The results suggest that beyond 7 injections, there is little likelihood of additional gains in visual acuity, said Heinrich Gerding, MD, an ophthalmologist in the Department of Retinology at Pallas Clinic Olten in Switzerland.

Dr. Gerding presented the results here at the 14th EURETINA Congress.

The findings are similar to those of an earlier study that found that a flexible ranibizumab treatment regimen driven by visual acuity, rather than by the calendar, could sustain visual improvement and had the potential to reduce costs and risks associated with additional intravitreal injections, explained Dr. Gerding.

The authors of that study used a drug and disease model to estimate that 5.1 ranibizumab injections, on average, would be needed to maintain visual acuity beyond the first 3 monthly injections, for a total of 8.1 in the first year ( IOVS. 2010:51;1:405-412).

Dr. Gerding performed a Medline search and identified 54 case series — 27 prospective and 27 retrospective — involving intravitreal injections of ranibizumab into a total of 11,705 eyes. The mean age of patients was 78.2 ± 2.6 years. The mean number of ranibizumab injections during a 12-month period was 6.3 ± 2.0.

He then used both linear and nonlinear regression analyses to calculate the relation between the number of injections and functional outcomes, defined as the average gain in visual acuity, the percentage of eyes losing more than 15 letters of acuity on the Early Treatment Diabetic Retinopathy Study (EDTRS) chart, and the percentage gaining 15 or more letters within the first year of treatment.

Dr. Gerding saw that the mean gain in visual acuity was 4.9 ± 3.6 letters on the ETDRS chart. The large majority of eyes (92.4% ± 3.9%) lost less than 3 lines of visual acuity, and one fourth (24,5% ± 8.2%) gained more than 3 lines within the first year.

The figure of an average of 7 injections in the first year is probably a very good one. Dr. Michael Larsen

When Dr. Gerding analyzed the relation between the number of injections given and visual gain, he saw a nonlinear pattern, defined by "a nearly stepwise improvement of functional gain" that occurred between 6.8 and 7.1 injections during a 12-month period. Beyond that level, there was a saturation effect, indicating that there was little if any improvement to be gained with additional injections in the first year. A similar, nonlinear pattern with little additional benefit beyond 7 or so injections emerged when he looked at the number of injections vs the percentage of patients who lost more than 15 letters.

"At a level of more than 7.1 injections in 1 year, the difference between PRN and monthly treatment seems to become marginal," said Dr. Gerding.

"The figure of an average of 7 injections in the first year is probably a very good one. This is in populations of patients, of course. Within populations there is a lot of variability," said Michael Larsen, MD, professor of clinical ophthalmology at the University of Copenhagen in Denmark, who was comoderator of the session in which the data were presented.

Although the meta-analysis "is a little bit of a data mess," because of the different designs and the retrospective nature of half of the included study, the information provided is clinically relevant and could spare some patients from the additional costs, risks, and inconvenience of unnecessary injections, Dr. Larsen told Medscape Medical News.

Dr. Gerding and Dr. Larsen report no relevant financial relationships.

14th EURETINA Congress. Presented September 12, 2014.


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