Glaucoma survey looks for gap between clinical trials and daily practice

Respondents were most likely to adhere to recommendations of the Ocular Hypertension Treatment Study.

The impact of clinical glaucoma trials on real-life practice varies greatly, according to a member survey of the American Glaucoma Society that appeared in the Journal of Glaucoma.

“Over the past several decades, numerous randomized multicenter clinical trials (RCTs) have provided valuable information to help guide clinical practice,” lead author Joseph F. Panarelli, MD, an assistant professor of ophthalmology at the Icahn School of Medicine at Mount Sinai in New York, said. “While we knew that a well-designed RCT provides the highest level of evidence, we wanted to further explore what RCTs had the greatest clinical value and why they made an impact on practice patterns.”

The survey, which was conducted while Panarelli was a glaucoma fellow at Bascom Palmer Eye Institute, asked AGS members to assess the clinical impact of eight RCTs. There was a 23% response rate, 206 of 894 society members, of whom 46.4% were self-described as academic practitioners with the remainder in private practice.

“After carefully reviewing the results, the biggest surprise to me was that even if you change a clinician’s viewpoint, it does not guarantee a commensurate impact on clinical practice, as we saw with the responses pertaining to laser trabeculoplasty,” Panarelli told Ocular Surgery News. “Nearly 70% of respondents said that laser trabeculoplasty was as safe and effective as medical therapy; however, only 43% would recommend it as first-line treatment.”

Tube Versus Trabeculectomy

Another question with a highly variable and compelling response was whether tube shunt surgery should be performed instead of trabeculectomy with mitomycin C in patients who have undergone prior cataract extraction.

“Half of responders disagreed with performing tube shunt surgery in these cases, while the remaining individuals were either ambivalent or agreed with this approach (22.2% and 23.6%, respectively),” Panarelli said.

Trabeculectomy still appears to be the “go-to procedure” after cataract extraction, despite the findings of the Tube Versus Trabeculectomy Study, “which found a higher rate of success with tube implantation compared to trabeculectomy in pseudophakic eyes,” Panarelli said.

The two trials with the highest mean scores for how likely a study impacted one’s clinical practice were the Ocular Hypertension Treatment Study (OHTS) and the Collaborative Normal-Tension Glaucoma Study (CNTGS).

“OHTS was the first large prospective RCT that demonstrated the benefit of IOP-lowering therapy in reducing the risk of developing glaucomatous damage among those with ocular hypertension, whereas CNTGS taught us that we should try to lower IOP by 30% in patients with normal-tension glaucoma and repeat visual fields to confirm or refute possible progression,” Panarelli said.

Differences matter

The authors noted there was a tendency for RCTs to be rated as having a higher impact if results showed a difference between randomized treatment groups. The quality and content of the two study-specific questions also may have influenced a respondent’s answer to the third question concerning the trial’s overall impact.

“For example, the importance of repeating visual fields to confirm or refute glaucomatous progression is a fundamental concept in glaucoma management,” Panarelli said. “Posing a question about this in the context of CNTGS could have positively influenced the overall rating of this study.”

Similarly, for OHTS, the survey asked if clinicians routinely check central corneal thickness, of which 99% of respondents said they do.

“Again, a positive response to this question may have strongly influenced the rating of this study,” Panarelli said.

Interestingly, the two studies with the highest and lowest score, OHTS and the European Glaucoma Prevention Study (EGPS), respectively, both addressed whether there was benefit to using topical therapy to treat patients with ocular hypertension.

“One reason for the difference in impact was that our survey was completed by American glaucoma specialists, while EGPS was primarily performed in Europe,” Panarelli said. “Being directly involved in a study likely influences the impact of the study on one’s practice. In the future, we would like to have members of similar organizations around the world participate in the survey and see if results vary.” – by Bob Kronemyer

For more information:

Joseph F. Panarelli, MD, can be reached at 310 E. 14th St., Suite 319S, New York, NY 10003; 212-614-8234; email: jpanarelli@nyee.edu.
Disclosure: Panarelli has no relevant financial disclosures.