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VANCOUVER -- Patients with proliferative diabetic retinopathy (PDR) had similar 5-year vision outcomes when treated with intravitreal ranibizumab (Lucentis) or panretinal photocoagulation (PRP), a randomized study showed.

Both treatments led to mean visual acuity improvement of about 3 letters and a mean visual acuity of 20/25 (approximate Snellen equivalent) versus 20/32 at baseline. Vision-impairing diabetic macular edema (DME) occurred significantly more often in patients treated with PRP. Rates of major systemic adverse events did not differ significantly between treatment groups.

The superior vision outcome with ranibizumab observed at 2 years failed to hold up to the end of the trial, Jeffrey G. Gross, MD, of the Carolina Retina Center in Columbia, South Carolina, reported here at the meeting.

"The mean change in visual acuity with ranibizumab was similar to panretinal photocoagulation at 5 years," said Gross. "Loss to follow-up was relatively high in both groups. Substantial visual acuity loss was rare. Visual field loss progressed in both groups during years 2 through 5, and the difference between groups diminished. Vitreous hemorrhage occurred in almost 50% of both groups."

"These findings support either ranibizumab or panretinal photocoagulation as viable treatment for proliferative diabetic retinopathy," Gross added. "Patient-specific factors -- including anticipated visit compliance, cost, and frequency of visits -- should be considered when choosing treatment for proliferative diabetic retinopathy."

The results were published simultaneously in .

PDR remains the leading cause of blindness among working-age adults in the United States, contributing to as many as 24,000 cases a year. PRP emerged as standard treatment for PDR more than 40 years ago. More recently, intravitreal injection of agents such as ranibizumab and bevacizumab (Avastin) targeting vascular endothelial growth factor (VEGF) emerged as a viable alternative to PRP.

The conducted a randomized clinical trial, known as Protocol S, to compare PRP and ranibizumab inpatients with PDR. The showed a 2.6-letter difference in mean change in visual acuity, a significant difference in visual acuity area under the curve, and significantly less peripheral visual field loss for the ranibizumab group. Patients treated with the anti-VEGF agent also had a lower incidence of vision-impairing DME and fewer vitrectomies.

Investigators at 55 U.S. sites enrolled patients in Protocol S. Eligible patients had a diagnosis of PDR, no prior treatment with PRP, and a best-corrected visual acuity (BCVA) letter score of ≥24 (approximate Snellen equivalent ≥20/320).

The study included 394 study eyes and 305 patients. When both eyes were treated, each eye was randomized separately to the treatment arms.

Patients in both treatment arms received a baseline intravitreal injection of ranibizumab for DME. Those assigned to ranibizumab then received monthly injections through 24 weeks. Injections could be deferred at that point on the basis of clinician judgment regarding neovascularization status. Injections resumed if neovascularization worsened. Patients who met protocol-specified criteria for failure or futility could receive PRP.

Patients assigned to PRP received treatment in a single session or in several sessions. Additional PRP could be performed during follow-up if neovascularization worsened, and patients could receive additional ranibizumab injections at clinician discretion. The mean number of ranibizumab injections over 5 years was 19.2 in the ranibizumab arm and 5.4 in the PRP arm. Patients in the ranibizumab arm had twice as many office visits (median of 43 versus 21 in the PRP group).

The primary outcome was mean change in visual acuity at 5 years. The results showed a mean change of 3.1 letters in the ranibizumab arm and 3.0 letters in the PRP arm. The mean change in AUC letter score was 3.3 with ranibizumab and 1.5 with PRP (adjusted mean difference 1.6, 95% CI 0-3.2, P=0.05). An analysis of peripheral vision in 80 treated eyes favored ranibizumab, which had a cumulative visual field total point score of -330 versus -527 with PRP (difference 208, 95% CI 9-408).

Vision-impairing DME occurred significantly less often in the ranibizumab group (22% of eyes versus 38%, HR 0.4, 95% CI 0.3-0.7, P<0.001). Retinal detachment also occurred less often in eyes randomized to ranibizumab (7% versus 18%, HR 0.4, 95% CI 0.2-0.8, P=0.004), and almost twice as many vitrectomies were performed in the PRP arm (39 versus 21). Vitreous hemorrhage occurred in 48% of the ranibizumab eyes and 46% of the PRP-treated eyes. The incidence of endophthalmitis was 0.03% in the ranibizumab arm and 0 in the PRP arm.

The dropout rate was substantial in both groups. After excluding patients who died during follow-up, two thirds of study participants completed the 5-year visit, with no difference between treatment groups.