Expensive Tube-Shunt Surgery Cost-Effective in Glaucoma

Miriam E. Tucker

February 28, 2014

WASHINGTON, DC — Baerveldt tube-shunt surgery for glaucoma is cost-effective, despite the fact that it is more expensive than trabeculectomy, the gold-standard treatment, a new study has found.

The results of a cost-effectiveness analysis based on a meta-analysis of published literature were presented here at the American Glaucoma Society 24th Annual Meeting by Richard Kaplan, BA, a graduating medical student at Columbia University in New York City.

"This study has justified the increased cost of the tube-shunt procedure. As such, clinical decisions regarding choice of surgery are best left to the surgeon's discretion," Kaplan told Medscape Medical News.

The Tube vs Trabeculectomy (TVT) trial showed that the increasingly popular tube-shunt procedures are as effective as the one-time gold standard of trabeculectomy with mitomycin C for lowering intraocular pressure, as reported by Medscape Medical News. In addition, rates of failure and reoperation were lower in patients who had undergone previous eye surgery. However, cost-effectiveness data were limited.

This analysis "reinforces the idea that the cost of the implant doesn't outweigh the benefits," said session moderator Tak Yee Tania Tai, MD, from the New York Eye and Ear Infirmary at the Mount Sinai School of Medicine in New York City.

Within the "Willingness to Pay" Standard

Kaplan and colleagues used Medicare reimbursement codes, Red Book medication costs, and Markov modeling to compare the cost of tube-shunt surgery and trabeculectomy. In their analysis, they evaluated factors such as rates of success, the number of supplemental medications, rates of severe complications, and associated visual outcomes.

Patient-derived utilities, based on visual field and visual acuity outcomes, were represented by quality-adjusted life years (QALYs), or the number of life-years saved adjusted for the loss of quality.

Over 5 years, actual costs were $8380 for trabeculectomy and $10,594 for tube insertion. However, patient utility was slightly higher in the tube group than in the trabeculectomy group (3.38 vs 3.31 QALYs).

Cost-effectiveness ratios were $2532 per QALY for trabeculectomy and $3134 per QALY for tube insertion. The incremental cost-effectiveness ratio — the higher cost of the tube-shunt procedure divided by the increase in effectiveness — was $32,128, which is well within the accepted cost-effectiveness "willingness to pay" standard of $50,000 per QALY gained, Kaplan noted.

On sensitivity analysis, lowering the failure rate for trabeculectomy by 5.5% (the difference between the TVT and the analysis failure rates) did not raise the incremental ratio above $50,000, nor did raising the failure rate for the tube by 3.3% (same calculation). However, doing both simultaneously did raise the incremental cost-effectiveness ratio above $50,000.

Using branded medications, assuming 0% diplopia and hypotony maculopathy, and adding the cost of reoperation for failure and the increased visit costs for trabeculectomy did not push the tube procedure above the cost-effectiveness threshold.

This analysis "demonstrated that the Baerveldt is cost-effective," Kaplan told Medscape Medical News. "However, it did not account for individual patient factors that influence the choice of procedure. As such, although the findings demonstrate that tube surgery results in marginally higher utility, as measured by QALYs, given the relatively small difference in QALYs between the 2 groups, surgeon preference should dictate surgical decision making."

Dr. Tai noted that on the basis of these data, along with those from the TVT study, "I might have a lower threshold for a tube shunt in a patient who may have had previous surgery."

However, she added, "usually for primary open-angle glaucoma, if the patient hasn't had a previous glaucoma surgery, I still start off with a trab. If that fails, I can still put in a tube afterward. It is more difficult to do a trab after the patient has already had a tube placed."

Mr. Kaplan and Dr. Tai have disclosed no relevant financial relationships.

American Glaucoma Society (AGS) 24th Annual Meeting: Abstract 1. Presented February 27, 2014.

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