New research published in the American Journal of Ophthalmology used the American Academy of Ophthalmology (AAO) Intelligent Registry in Sight (IRIS) Registry to provide updated data on a landmark study: the tube versus trabeculectomy (TVT) randomized control trial (RCT) study.
Let’s start with this original study.
Launched in 1999, the TVT RCT study was a multicenter, randomized, prospective, interventional study (NCT00306852) that compared the safety and efficacy of:
- Baerveldt 350 mm2 glaucoma implant (BGI)
- Trabeculectomy with mitomycin C (MMC)
A total of 212 patients (ages 18 to 85 years) were enrolled, each with a history of ocular surgery (such as cataract).
And the results?
Published in 2007, the 1-year data found the eyes that underwent trabeculectomy had a higher failure rate versus BGI-treated eyes; this continued through the 5-year follow-up.
A reduction in intraocular pressure (IOP) at 1-year also presented with similar data for both procedures; however, MMC-treated patients had less of a need for supplemental medical therapy following the procedure.
Furtherat the 1-year mark, BGI-treated patients were less likely to undergo glaucoma surgery again.
See the complete results here.
Now this new study.
As a retrospective clinical cohort study, the TVT IRIS study used the IRIS Registry to analyze electronic health record (EHR) data from 1-year post-surgical outcomes of a cohort of patients who received either:
- Non-valved tube shunt surgery (236 eyes)
- Trabeculectomy (183 eyes)
Note the following:
- All IRIS Registry data was from 2013 to 2017.
- All tube types were included in the IRIS Registry data.
- IRIS Registry could not determine if trabeculectomy used MMC
- All trabeculectomy procedures were included.
And what was being compared?
Researchers assessed the following averaged outcomes between both studies at 1-year follow-up:
- IOP
- Number of glaucoma medications
- Reoperations for glaucoma or additional surgery
- Visual acuity (VA)
Results?
Researchers observed a significant IOP reduction for both groups:
- Trabeculectomy
- 25.3 ± 6.4 mmHg (baseline) to 13.5 ± 5.2 mmHg
- Tube
- 26.6 ± 6.5 mmHg (baseline) to 14.3 ± 4.8 mmHg
And compared?
IOP reductions for both groups in both studies were similar; however, the TVT RCT study groups used fewer glaucoma medications than the TVT IRIS study groups at all time points during the first year.
- Trabeculectomy
- 2.5 vs 2.3 medications, p = 0.058
- Tube
- 1.7 vs 1.3 medications, p < 0.001
Note: this difference was likely due to the inclusion of valved tubes in the TVT RCT groups.
What about reoperations?
The reoperation rates were significantly different for the tube groups in both studies while the reoperation rates for the trabeculectomy groups were only marginally different.
To note, the TVT IRIS groups were consistently higher in percentages than the TVT RCT groups.
- Tubes
- 6.4% vs 1.0%, p = 0.023
- Trabeculectomy
- 8.7% vs 5.5%, p = 0.0729
And VA?
Both treatment groups in TVT IRIS observed significant decreases in VA:
- Tube
- 0.31 ± 0.42 (baseline) to 0.38 ± 0.51 (P = 0.0279)
- Trabeculectomy
- 0.44 ± 0.49 (baseline) to 0.54 ± 0.59 (P = 0.0039)
Explain, please.
Compared to TVT RCT, the baseline and 1-year VA were not significantly different (for the tube groups); however, TVT RCT had a greater mean reduction.
And for the trabeculectomy groups in both studies, the VA differences were similar at both time timepoints; however, TVT IRIS had a significantly better VA.
Conclusion?
Overall, the authors concluded that the TVT IRIS study’s data is comparable to that of the TVT RCT, suggesting that “the IRIS Registry can be used to accurately assess real-world outcomes of surgical interventions,” they wrote.
Take home.
The authors further stated that both RCTs and real-world studies using EHR data, “provide valuable information for informing surgical outcomes, and should be used together to improve patient care in the future.”