Sociodemographic and Economic Factors in Outcomes of Tube Shunts for Neovascular Glaucoma

ABSTRACT

Importance: Few studies have analyzed associations between sociodemographic factors and neovascular glaucoma (NVG) outcomes.

Aim and background: To determine the potential impact of sociodemographic and economic factors on the NVG tube shunt surgery outcomes.

Design: Retrospective, single-center, comparative case series.

Participants: Consecutive patients who underwent tube shunt surgery for NVG and had ≥6 months of follow-up.

Materials and methods: Regional average adjusted gross income (AGI) was determined by cross-referencing self-reported residential zip codes with average AGI per zip code supplied by the Internal Revenue Service. Two groups were created: (1) lower-income: individuals from neighborhoods with the lowest 10% of AGI (near the United States poverty line), (2) higher-income: the remaining 90% of individuals.

Main outcome measures: Visual acuity (VA), intraocular pressure (IOP), and glaucoma medication number at 6 months and the most recent visit.

Results: The mean annual AGI in the higher-income group (130 patients) was $69,596 ± 39,700 and the lower-income group (16 patients) was $27,487 ± 1,600 (p %3C; 0.001). Age, sex, distance to the clinic, language, and all baseline clinical variables (including VA and IOP) were comparable between groups. Lower-income was associated with non-white race (81.3 vs 52.3%; p = 0.024). At month 6, VA in the lower-income group [median: HM (20/70–NLP)] was worse than the higher-income group [median: CF (20/25–NLP)] (log MAR VA: 2.32 ± 0.8 vs 1.77 ± 1.1; p = 0.02); these trends persisted through the most recent visit (p = 0.043). Follow-up IOP and medications were similar between groups.

Conclusions and relevance: Lower-income may be associated with worse VA outcomes following NVG tube shunt surgery.

INTRODUCTION

Neovascular glaucoma (NVG) is a type of secondary glaucoma that can result in catastrophic vision loss.¹ Neovascular glaucoma is most commonly preceded by proliferative diabetic retinopathy, central retinal vein occlusion, central retinal artery occlusion, or ocular ischemic syndrome.¹ The management of NVG includes medical or surgical reduction of intraocular pressure (IOP) and treatment of the underlying posterior segment ischemia-inducing neovascularization. Surgical interventions in the form of filtering procedures or cyclophotocoagulation are often necessary when medical therapy fails, especially in the presence of synechial angle closure.² Tube shunt implantation has been described in several studies as the mainstay of therapy for NVG.^3–5 Additionally, underlying retinal ischemia is treated by panretinal photocoagulation (PRP) and/or intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) agents, which reduce the production of angiogenic factors and induce regression of neovascularization.⁶

The impact of sociodemographic and economic factors on general health outcomes has been widely investigated.^7–12 The prevalence of nearly all chronic conditions, including stroke, heart disease, and arthritis has been shown to increase as income declines.⁷ Economic inequality in the United States is among the highest of developed nations, and there is a life expectancy gap of 10–15 years between the wealthiest and poorest 1% of the American population.^11,12 In addition to income, factors including race, sex, ethnicity, primary language, education, housing, employment, and health insurance status have been shown to have a significant association with general health outcomes.^13–19

The literature on associations between sociodemographic and economic factors and ophthalmic health outcomes is limited.^13–18 Healthcare disparities in ophthalmology have been associated with race, sex, education, and income.^13–16 Although NVG is common secondary glaucoma and tends to affect those with poor general health,¹ few studies have analyzed associations between sociodemographic factors and NVG outcomes. This study aimed to investigate a potential relationship between income and visual acuity (VA) and IOP outcomes after glaucoma tube shunt implantation in patients with NVG.

MATERIALS AND METHODS

RESULTS

DISCUSSION

Higher burdens of illness, disability, and mortality have been associated with lower socioeconomic status across the medical specialties.^7–12 The ophthalmic literature on the association between sociodemographic and economic factors and clinical presentation,^18,21,22 surgical outcomes,¹⁷ and adherence to treatment is limited.^23,24 Our study analyzed a possible relationship between income and outcomes after surgery for NVG and found that despite similar preoperative characteristics in the two groups, those with lower income had significantly worse VA at postoperative month 6 and at their most recent visit.

To our knowledge, ours is the first study to investigate the association between sociodemographic and economic factors and surgical outcomes in NVG. Preoperative severe vision loss was dominant in both groups (75.0 and 70.0% in the lower- and higher-income groups, respectively, p = 0.679). However, the higher-income group experienced significant improvement in VA by postoperative month 6, while those in the lower-income group had increasingly larger proportions of severe vision loss over time. The potential reasons for these disparate outcomes are many. First, reversible causes of poor vision (e.g., corneal edema) before surgery may have led to decreased VA in the higher income group. Initial severe vision loss may have been due to reversible and irreversible causes including corneal edema, macular edema and/or ischemia, vitreous hemorrhage, and glaucoma. It is possible that the higher income group had more reversible causes of visual loss as their VA improved over the course of the study. Of note, the presence of cataracts at all time points was similar between the two groups, making it unlikely that lens opacity was more likely to be the etiology of worsening vision.

Additionally, the lower-income group may have had more severe retinal pathology at baseline or may have presented later in the course of disease with significant optic nerve damage and/or retinal ischemia. Our tertiary care center often receives urgent referrals for NVG patients from outside practices where patients may have initially presented, making it difficult to know the duration of NVG and retinal pathology, both of which may have had an impact on final VA outcomes. Poor outcomes may have been associated with more advanced presentation. Moreover, while both groups received similar perioperative retinal treatment (PRP or intravitreal injection within 2 weeks of surgery), it is possible that the lower-income group was not able to continue close retinal follow-up, although adherence to glaucoma visits was similar between the two groups. Notably, IOP reduction, 6-month surgical failure, and surgical complications were similar for both groups at all time points. Furthermore, the difference in the proportions of trainees performing surgery in each group was not statistically significant, and a prior study has shown that tube shunt surgery performed by residents are as effective and safe as surgeries performed by attendings.²⁵

Furthermore, the lower-income group had a higher proportion of non-white race (p = 0.024), which may have affected surgical outcomes. Previous studies have suggested that the black race may be associated with a higher failure rate after trabeculectomy or tube shunt surgery, however, this is controversial.^26–30 Studies on intravitreal injections to treat proliferative diabetic retinopathy and retinal vein occlusion have suggested that African Americans and those with lower income are vulnerable to poor follow-up.^23,24 Notably, NVG is most commonly caused by these ischemic disorders,¹ which suggests that these results may be applied to NVG patients as well. Although we included patients who had at least 6 months of follow-up with the glaucoma service after the tube shunt surgery, we did not investigate their postoperative retinal treatment schedule. Long-term adherence to repeated retinal treatment may have varied between the lower- and higher-income groups and may be reflected on their visual outcomes despite similar IOP control. Although the language may represent a barrier to healthcare access, potentially increasing the incidence of disease complications,³ our sample showed no difference between the higher- and lower-income groups regarding the prevalence of the non-English speakers (p = 0.265).

Previous studies have investigated the impact of sociodemographic and economic status on ophthalmic outcomes.^17,18,21,22 Socioeconomic deprivation and African-Caribbean race have previously been associated with advanced disease on presentation, making these groups more likely to experience major vision loss from glaucoma.^21,22 Likewise, adverse economic conditions have been associated with blindness in NVG patients.³² Moreover, studies on age-related macular degeneration have demonstrated that lower-income and non-white races are risk factors for severe vision loss at presentation.¹⁸ Similarly, these are risk factors for the fovea-off presentation of rhegmatogenous retinal detachment, subsequent higher risk of reoperation, and worse postoperative VA.¹⁷ Furthermore, a systematic review of studies that evaluated major acquired causes of visual loss (including cataract, diabetic eye disease, glaucoma, age-related macular degeneration, and ocular trauma) reported a higher risk of vision loss between these disease entities and socioeconomic deprivation.³³ While the disease process studied in our report is distinct from prior studies on income and health outcomes, a trend of worse VA outcomes in those with a lower income is consistent across the literature. Our findings suggest that NVG patients are also subject to these unfortunate associations between socioeconomic status and ocular health.

This study is not without limitations. These include its retrospective design and lack of information about diabetic control (as tight glycemic control in diabetic patients slows the progression of diabetic retinopathy with subsequent NVG³⁴), and the inclusion of both Baerveldt glaucoma implants and Ahmed glaucoma valves. Additionally, this study, similar to those previously published,^17,18,23,24 used Internal Revenue Service data to calculate income, as opposed to patients’ reports of income. Additionally, as we were comparing 10% of the sample to the remaining 90%, sample sizes were not balanced between the groups, which may have limited our ability to detect differences. Strengths include a considerable sample size given the subject matter and inclusion of consecutive patients.

CONCLUSION

To our knowledge, this is the first study to investigate an association between sociodemographic and economic factors and surgical outcomes in NVG. Our findings suggest that patients from neighborhoods with an average income near the United States poverty line are at higher risk of worse VA outcomes following tube shunt surgery for NVG than patients from more affluent neighborhoods. We further demonstrate that sociodemographic and economic inequalities are associated with health outcomes. Additional study on this potential association is warranted and may help guide clinicians in counseling patients and provide further insight regarding reasons for worse visual outcomes in the most vulnerable populations.

CLINICAL SIGNIFICANCE

To our knowledge, this is the first study to investigate an association between sociodemographic and economic factors and surgical outcomes in NVG. This investigation demonstrated the potential relationship between low income and poor visual outcomes in NVG.

REFERENCES

1. Hayreh SS. Neovascular glaucoma. Prog Retin Eye Res 2007;26(5):470–485.

2. Olmos LC, Lee RK. Medical and surgical treatment of neovascular glaucoma. Int Ophthalmol Clin 2011;51(3):27–36.

3. Netland PA. The Ahmed glaucoma valve in neovascular glaucoma (An AOS Thesis). Trans Am Ophthalmol Soc 2009;107:325–342.

4. Sidoti PA, Dunphy TR, Baerveldt G, et al. Experience with the Baerveldt glaucoma implant in treating neovascular glaucoma. Ophthalmology 1995;102(7):1107–1118.

5. Budenz DL, Barton K, Gedde SJ, et al. Five-year treatment outcomes in the Ahmed Baerveldt comparison study. Ophthalmology 2015;122(2):308–316.

6. Alkawas AA, Shahien EA, Hussein AM. Management of neovascular glaucoma with panretinal photocoagulation, intravitreal bevacizumab, and subsequent trabeculectomy with mitomycin C. J Glaucoma 2010;19(9):622–626.

7. Dickman SL, Himmelstein DU, Woolhandler S. Inequality and the health-care system in the USA. Lancet 2017;389(10077):1431–1441.

8. Hargraves JL, Hadley J. The contribution of insurance coverage and community resources to reducing racial/ethnic disparities in access to care. Health Serv Res 2003;38(3):809–829.

9. Nelson A. Unequal treatment: confronting racial and ethnic disparities in health care. J Natl Med Assoc 2002;94(8):666–668.

10. Manuel JI. Racial/ethnic and gender disparities in health care use and access. Health Serv Res 2018;53(3):1407–1429.

11. Waldron H. Trends in mortality differentials and life expectancy for male social security-covered workers, by socioeconomic status. Soc Secur Bull 2007;67(3):1–28.

12. Chetty R, Stepner M, Abraham S, et al. The association between income and life expectancy in the United States, 2001-2014. JAMA 2016;315(16):1750–1766.

13. Arora S, Kurji AK, Tennant MT. Dismantling sociocultural barriers to eye care with tele-ophthalmology: lessons from an Alberta Cree community. Clin Invest Med 2013;36(2):E57–E63.

14. Zambelli-Weiner A, Crews JE, Friedman DS. Disparities in adult vision health in the United States. Am J Ophthalmol 2012;154 (6 Suppl):S23–30.e1.

15. Chou CF, Barker LE, Crews JE, et al. Disparities in eye care utilization among the United States adults with visual impairment: findings from the behavioral risk factor surveillance system 2006-2009. Am J Ophthalmol 2012;154 (6 Suppl):S45–52.e1.

16. Hollar MW, Zhang MM, Mawn LA. Ophthalmic disparities in transgender patients. Semin Ophthalmol 2016;31(4):426–431.

17. Xu D, Uhr J, Patel SN, et al. Sociodemographic factors influencing rhegmatogenous retinal detachment presentation and outcome. Ophthalmol Retina 2021;5(4):337–341.

18. Patel SN, Wu C, Obeid A, et al. Sociodemographic factors in neovascular age-related macular degeneration. Ophthalmology 2020;127(2):280–282.

19. Palacios-Barrios EE, Hanson JL. Poverty and self-regulation: Connecting psychosocial processes, neurobiology, and the risk for psychopathology. Compr Psychiatry 2019;90:52–64.

20. Office of the Assistant Secretary for planning and evaluation. 2020 Poverty Guidelines. https://aspe.hhs.gov/2020-poverty-guidelines . Published 2020.Accessed January 21, 2020.

21. Ng WS, Agarwal PK, Sidiki S, et al. The effect of socio-economic deprivation on severity of glaucoma at presentation. Br J Ophthalmol 2010;94(1):85–87.

22. Fraser S, Bunce C, Wormald R, et al. Deprivation and late presentation of glaucoma: case-control study. BMJ 2001;322(7287):639–643.

23. Obeid A, Gao X, Ali FS, et al. Loss to follow-up in patients with proliferative diabetic retinopathy after panretinal photocoagulation or intravitreal anti-VEGF injections. Ophthalmology 2018;125(9):1386–1392.

24. Gao X, Obeid A, Adam MK, et al. Loss to follow-up in patients with retinal vein occlusion undergoing intravitreal anti-VEGF injections. Ophthal Surg Lasers Imag Retina 2019;50(3):159–166.

25. Thangamathesvaran L, Crane E, Modi K, et al. Outcomes of resident-versus attending-performed tube shunt surgeries in a United States residency program. J Curr Glaucoma Pract 2018;12(2):53–58.

26. Broadway DC, Chang LP. Trabeculectomy, risk factors for failure and the preoperative state of the conjunctiva. J Glaucoma 2001;10(3):237–249.

27. Budenz DL, Barton K, Feuer WJ, et al. Treatment outcomes in the Ahmed Baerveldt comparison study after 1 year of follow-up. Ophthalmology 2011;118(3):443–452.

28. Christakis PG, Kalenak JW, Zurakowski D, et al. The Ahmed versus Baerveldt study: one-year treatment outcomes. Ophthalmology 2011;118(11):2180–2189.

29. Gedde SJ, Schiffman JC, Feuer WJ, et al. Treatment outcomes in the tube versus trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol 2012;153(5):789–803.e2.

30. Taubenslag KJ, Kammer JA. Outcomes disparities between black and white populations in the surgical management of glaucoma. Semin Ophthalmol 2016;31(4):385–393.

31. Zheng Y, Lamoureux EL, Chiang PC, et al. Language barrier and its relationship to diabetes and diabetic retinopathy. BMC Public Health 2012;12:781.

32. Ndiaye-Sow MN, Seck SM, Dieng M, et al. Profile of neovascular glaucoma in senegalese patients. J Fr Ophtalmol 2018;41(7):637–641.

33. Lane M, Lane V, Abbott J, et al. Multiple deprivation, vision loss, and ophthalmic disease in adults: global perspectives. Surv Ophthalmol 2018;63(3):406–436.

34. Group AS, Group AES, Chew EY, et al. Effects of medical therapies on retinopathy progression in type 2 diabetes. N Engl J Med 2010;363(3):233–244.

Keywords: Ahmed glaucoma valve, Baerveldt glaucoma implant, Glaucoma surgery, Income, Neovascular glaucoma, Race, Sociodemographic, Socioeconomic, Tube shunt.