Characterizing the Healthcare Resource Utilization and Costs By Disease Severity Among Patients with Geographic Atrophy Secondary to Age-Related Macular Degeneration

Thesis (Master's)--University of Washington, 2019Background: Geographic atrophy (GA) is an advanced form of dry age-related macular degeneration (AMD) that affects nearly one million people in the United States (US), and 5 million people worldwide, with no current treatments available to slow or prevent the progression of GA. The disease progression has been shown to be associated with a decline in vision-related quality of life and increased expenditures, particularly in bilateral GA. With considerable interpatient variability in the rate of GA progression due to lesion characteristics, there is no standardized GA severity scale that assesses disease severity and tracks disease progression. Previous research characterizing the burden of GA is scarce, and lacks stratification by lesion type. Objective: To characterize the incidence and prevalence of GA, and examine incident cases of GA to determine the all-cause resource utilization and direct payer-related medical costs among patients diagnosed with GA in the US, overall and by disease severity. Methods: A retrospective cohort analysis was conducted using IQVIA PharMetrics Plus administrative claims data from 2015-2018. Patients who were newly diagnosed with GA were identified between October 1, 2016 and June 30, 2017, and eligible patients were classified by disease severity (early or intermediate AMD, GA without subfoveal involvement, GA with subfoveal involvement) and laterality based on ICD-10 codes. Baseline characteristics were evaluated during the 1-year period prior to the index date. Follow up was 12 months (defined by continuous health plan enrollment), in which the outcomes, such as healthcare resource utilization (HCRU) and direct costs, were evaluated. Negative binomial regression models were used to estimate the number of outpatient, emergency department, and inpatient visits, and linear regression was used to estimate average inpatient hospitalizations. Generalized linear models with gamma distribution and a log-link function were used to analyze healthcare costs. Cost data were adjusted to 2019 dollars. All models adjusted for patient demographics and comorbidities. Cost models also adjusted for baseline HCRU and costs in the 12-months prior to index diagnosis. Results: A total of 14,421 patients were included in the study: 20% had unilateral GA, of which 93.2% had early or intermediate AMD, 3.8% had GA without subfoveal involvement, and 2.9% had GA with subfoveal involvement. Eighty percent had bilateral GA, of which 96.7% had early or intermediate AMD, 1.7% had GA without subfoveal involvement, and 1.5% had GA with subfoveal involvement. The mean number of OP, ED, and IP visits per GA patient was 20.9, 3.7, and 1.4, respectively. The mean cost per GA patient was $2,829 and $11,533 for the patient and payer, respectively. Patients with bilateral GA had, on average, higher unadjusted payer-related total healthcare costs and costs in each healthcare setting; however, significant associations did not persist after adjustment for baseline characteristics for costs and HCRU. Conclusion: Results from this real-world claims analysis suggest that patients with more severe forms of GA neither consume significantly more healthcare resources nor accrue greater costs. This may be due to the fact that this study identified all-cause, rather than disease-specific or disease-related, resources and costs. Specific contributing factors to the burden of GA were not explored. As such, further research is warranted to identify the increase in overall disease burden in patients with more severe levels of GA due to having more comorbidities, such as falls and fractures