Open-Angle Glaucoma And Glaucoma Filtration Surgery
Overview
This population-based historic cohort study, spanning from 1997 to 2017, aimed to investigate the rate and risk factors associated with glaucoma filtration surgery (GFS) in individuals newly diagnosed with open-angle glaucoma (OAG) aged 45 and above. The cohort comprised 9420 patients diagnosed with OAG between 1997 and 2010, and data on trabeculectomy (TRE), deep sclerectomy (DS), and glaucoma drainage implant (GDI) surgeries were gathered from national healthcare registers.
The cumulative incidence of GFS was analyzed over a 10-year period, revealing rates of 3.1% at 5 years and 5.4% at 10 years from the onset of OAG. Notably, individuals aged over 80 at baseline exhibited a lower incidence of GFS (IRR 0.51, CI 0.31–0.84), providing insights into age-related patterns in surgical intervention.
A crucial finding was the correlation between the number of intraocular pressure (IOP)-lowering drugs administered in the initial two years of treatment and the risk of GFS. The incidence rate ratios (IRRs) demonstrated a progressive increase, with values of 3.23 (CI 2.32–4.50) for two drugs, 7.44 (CI 5.28–10.47) for three drugs, and 14.95 (CI 10.38–21.52) for four drugs, highlighting the significance of medication intensity in predicting the likelihood of surgical intervention.
In conclusion, this study contributes valuable insights into the treatment trajectory of OAG, specifically delineating the role of GFS within the spectrum of glaucoma therapies. The findings underscore the nuanced relationship between age, medication regimen, and the propensity for surgical interventions, enriching our understanding of optimal management strategies for individuals with newly diagnosed OAG.
Introduction
Glaucoma, a cluster of optic nerve disorders leading to irreversible vision loss if untreated, ranks as the second major cause of global blindness, posing a significant public health concern, especially among aging populations. Key risk factors for open-angle glaucoma (OAG) include elevated intraocular pressure, advanced age, sub-Saharan African ethnicity, familial history, and high myopia. Lowering intraocular pressure through medication, laser treatments, or surgery is the prevailing strategy to avert glaucomatous vision loss. However, poor adherence to topical treatments and medication-related side effects often prompt consideration of alternative modalities. Glaucoma surgery, viewed not as a last resort but as a timely intervention, becomes necessary when vision preservation is unattainable by other means.
In the initial stages of glaucoma therapy, modifications are common, with nearly half of newly diagnosed OAG patients altering their initial treatment, and two-thirds undergoing further adjustments within the first four years. Early glaucoma procedures, such as selective laser trabeculoplasty and glaucoma filtration surgery (GFS), have shown potential benefits in reducing ophthalmology visits, treatment modifications, and costs.
While trabeculectomy remains the gold standard in glaucoma filtration surgery, various surgical approaches, with or without indwelling tubes and implants, are available. Despite an extensive global survey revealing a lack of published data on global glaucoma surgery rates, few studies have explored the factors influencing the risk of OAG patients undergoing GFS. Regional practice preferences, demographics, socioeconomic factors, and patient-related characteristics like medication usage, comorbidities, age, and gender may collectively determine the probability of surgical treatment.
This study seeks to address the dearth of information regarding the cumulative risk of GFS in newly diagnosed open-angle glaucoma patients, aiming to expand epidemiological knowledge. By investigating the rate of GFS over time, the research aims to contribute valuable insights for patients, clinicians, and healthcare policymakers. This information could enhance the optimization of glaucoma care, offering prognostic tools to assess the need for surgical services at the population level.
Method
The study draws on comprehensive data from three national healthcare registers in Finland to investigate the association between open-angle glaucoma (OAG) and various health parameters. The Social Insurance Institute (SII), responsible for national social security programs, provided data on medication reimbursements and dispensed prescriptions, serving as the foundation for cohort identification. Statistics Finland (SF) contributed information on mortality and employment status, while the Finnish Institute for Health and Welfare supplied data on hospital visits and surgical procedures.
The study focuses on a Finnish population-based subset, a part of the larger CARING cohort study, comprising 398,708 individuals. Originally designed for diabetes mellitus (DM) research, the cohort includes DM patients identified through prescribed insulin or oral antidiabetic medications. Reference individuals were matched by age, sex, and hospital district. Baseline characteristics encompassed age, sex, hospital district, comorbidities eligible for medication reimbursement, and socioeconomic group.
The study specifically examined individuals aged 45 years or older diagnosed with open-angle glaucoma (OAG) between January 1, 1997, and December 31, 2010. open-angle glaucoma patients were identified through reimbursements for glaucoma medication, meeting specific criteria related to intraocular pressure (IOP) and diagnostic conditions. The follow-up period commenced with the approval of glaucoma medication reimbursement and concluded with glaucoma surgery, death, or December 31, 2017, whichever came first. Patients with pre-existing glaucoma or specific types of glaucoma were excluded, and precautions were taken to prevent misclassification bias by excluding those with a history of relevant hospitalizations and procedures.
In summary, this meticulously designed study leverages data from Finnish national registers to explore the relationship between open-angle glaucoma and various health parameters within a well-defined cohort. The rigorous inclusion and exclusion criteria ensure the study’s robustness and reliability in examining the complexities surrounding open-angle glaucoma and associated health factors.
Statistical Analysis
The study employed descriptive statistics to examine the baseline characteristics of the cohort, focusing on the incidence of glaucoma filtration surgery (GFS) after the diagnosis of open-angle glaucoma (OAG). The primary outcome variable, GFS incidence, was analyzed using cumulative incidence curves and Poisson’s regression model, adjusting for various background variables such as age, sex, hospital district, systemic comorbidities, and the number of intraocular pressure (IOP)-lowering drugs. The researchers documented the number of glaucoma medications at the 2-year mark from open-angle glaucoma diagnosis, categorizing them into groups.
Three GFS procedures, namely trabeculectomy (TRE), deep sclerectomy (DS), and glaucoma drainage implant (GDI), were selected as endpoints for time-to-event analyses. The study utilized Nordic Medico-Statistical Committee (NOMESCO) codes to identify these procedures and R language for statistical calculations.
To explore the association between systemic medications and GFS risk, a nested case–control design was implemented. For each GFS-operated open-angle glaucoma patient, five conservatively treated controls were matched by sex, age, and hospital district. Systemic drugs accounting for a significant percentage of total prescriptions were analyzed, with exposure defined as a minimum of 2 years of continuous use, confirmed by at least two prescriptions per year in the last 5 years before the event. Conditional logistic regression was employed to report odds ratios with 95% confidence intervals.
Ethical considerations were paramount, with approvals obtained from the Ethics Committee of the Faculty of Medicine, University of Helsinki, as well as from relevant register holders, ensuring adherence to the principles of the Declaration of Helsinki. All data were pseudonymized and handled under strict confidentiality agreements, with due permissions granted for data handling from register holders.
Result
This cohort study focused on 9,420 patients newly diagnosed with open-angle glaucoma (OAG), with 55% females and 45% males, averaging 72.5 years at diagnosis. Of these patients, 4,325 had diabetes mellitus (DM), and 5,095 comprised the reference population. Over the 21-year study period, pensioners represented 63% of the cohort, totaling 59,100 person-years in follow-up.
The study documented 338 glaucoma filtration surgery (GFS) procedures, with an average annual rate of 6.9 GFS procedures per 1,000 persons. Three types of GFS procedures were studied, namely, deep sclerectomy (DS), trabeculectomy (TRE), and glaucoma drainage implantation (GDI). The cumulative incidence of GFS was 3.1% at 5 years and 5.4% at 10 years from OAG onset, with a mean follow-up time of 6.3 years.
The unadjusted rate of GFS was highest in patients initiated on glaucoma medication between 60 and 70 years of age. Employment status showed no association with the unadjusted rate of GFS. Multivariate analysis revealed that age over 80 years at OAG diagnosis was associated with lower GFS incidence. The type of GFS procedure was independent of age at open-angle glaucoma onset, and there was no significant difference in GFS risk between sexes.
The number of intraocular pressure (IOP)-lowering drugs in the first two years of open-angle glaucoma treatment exhibited a dose-dependent increase in GFS risk. Coexisting diabetes and various systemic comorbidities did not impact the rate of GFS. Analyzing 66 commonly used systemic drugs for associations with GFS risk, the study found that hydrochlorothiazide, furosemide, nitroglycerine, or memantine were linked with a lower risk of GFS. No drugs analyzed were associated with a higher risk of GFS.
In conclusion, this comprehensive study provides insights into factors influencing the incidence of GFS in open-angle glaucoma patients, emphasizing the role of age, IOP-lowering drug use, and specific systemic medications in this context.
Conclusion
This study investigated the incidence of glaucoma filtration surgery (GFS) in newly diagnosed open-angle glaucoma (OAG) patients within a historical population-based cohort. Over a 10-year period from the onset of OAG, 3.1% of patients underwent GFS, providing valuable epidemiological insights into the prognosis of OAG and its treatment trajectory. The findings contribute to the limited body of literature on glaucoma surgery rates and offer prognostic epidemiological data.
Compared to global glaucoma surgery rates, this study provides nuanced insights specific to Finland. The research period from 1997 to 2017, covering 9,420 patients, differs from other studies in terms of population size, follow-up time, case identification methods, and endpoint definitions. Notably, the study utilized a medication reimbursement database for case identification, ensuring a rigorous clinical and administrative process to exclude inconclusive findings.
The cumulative incidence of GFS at 10 years post-OAG diagnosis was 5.4%, emphasizing the importance of understanding glaucoma progression and treatment pathways. The study identified variations in GFS rates based on age, with a peak in patients diagnosed between 60 and 70 years, potentially influenced by factors such as risk of failure, concerns about complications, and the longevity of surgical success.
Moreover, the study explored potential associations between systemic factors and GFS rates. Notably, there were no significant differences in GFS rates between individuals with diabetes mellitus (DM) and their matched counterparts. Limited associations were observed with certain systemic drugs, suggesting a complex interplay between systemic comorbidities, drug usage, and the decision-making process for glaucoma surgery.
In conclusion, this research enhances our understanding of the epidemiology of GFS in open-angle glaucoma patients, offering valuable data for healthcare practitioners and policymakers. The study underscores the need for targeted healthcare interventions based on identified risk factors, paving the way for future research to explore nuanced associations between systemic factors and glaucoma progression.
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