A retrospective, case-control study published in the American Journal of Ophthalmology has found that as many as 70% of glaucoma patients have no record of gonioscopy within 6 months of diagnosis.
Give me some background first.
Gonioscopy is the diagnostic standard for detecting PACG and part of the preferred practice patterns for initial glaucoma evaluations.
However, previous studies have found suggestive evidence that gonioscopy is either underperformed or undercoded.
Now, talk about the study.
The study used national health claims data to identify which patient populations would be less likely to receive gonioscopy within 6 months of initial diagnosis.
The study used the Optum Clinformatics Data Mart, derived from a database of commercial and Medicare Advantage health claims data, to identify the study population.
Who was included in the study?
The study population included patients with a date of glaucoma or glaucoma suspect diagnosis within the 12-year period between 2009-2020, as well as continuous enrollment of at least 36 months.
The initial glaucoma evaluation also had to meet these criteria:
- Optical coherence tomography (OCT) retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), or visual field testing performed on or within 6 months of the index date of diagnosis
- No history of drops, laser procedures, or glaucoma surgery based on Current Procedural Terminology (CPT) codes (Supplementary Table 1) before the index glaucoma diagnosis date
Give me the details.
The study population included a total of 198,995 patients, of the following demographics:
- Race
- 65.1% non-Hispanic Whites
- 6.1% Asians
- 12.9% Blacks
- 12.1% Hispanics
- 3.8% of unknown race
- Age
- 66.0±14.1 years (range, 18 to 90 years)
- Glaucoma diagnosis
- 81.1% open-angle glaucoma suspect (OAGS)
- 5.7% anatomical narrow angle (ANA)
- 10.1% primary open-angle glaucoma (POAG)
- 1.2% primary-angle closure glaucoma (PACG)
- 1.9% were diagnosed with secondary glaucoma (SG)
Findings?
Overall, only 20.4% of patients had codes indicating they had received gonioscopy on the day of initial evaluation, and only 29.5% of patients appeared to have received gonioscopy within 6 months of initial evaluation.
Tell me more about the demographic breakdown.
Asians were more likely to have recorded gonioscopy within 6 months at 35.3%, followed by Hispanics (32.7%), Blacks (32.6%), and non-Hispanic Whites (27.9%).
Patients with PACG had a wide variability of recorded gonioscopy, with a range of 56.6% (Asians) compared to 73.5% (Blacks). OAGS, ANA, POAG, and SG all had lower variability.
Go on …
Older patients were less likely to have recorded gonioscopy, and perhaps most interestingly, those living in the Northeast were more likely to have recorded gonioscopy than those living elsewhere.
Expert opinion?
“The overall low rate of gonioscopy is striking,” wrote the study authors. “Overall, our present findings reiterate that gonioscopy is likely underperformed and/or underbilled on a nationwide level despite its clinical importance.”
Limitations?
The authors did note that this study had several limitations—chief among them being that it used health claims data, so doctors could be performing gonioscopy and simply not coding or miscoding the exam.
Additionally, they noted that they lacked granular clinical data that might have offered insight into when and why clinicians performed gonioscopy.
Take home.
“Current practice patterns may contribute to racial disparities in angle closure outcomes, especially among racial groups in whom the burden of PACG is less studied, such as Blacks and Hispanics,” the study authors wrote.
They added that, while gonioscopy remains the clinical standard that should be performed in all glaucoma evaluations, “our study supports the need for more convenient clinical methods to evaluate the angle,” such as anterior segment OCT (AS-OCT) imaging and other emerging methods.