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The purpose of the study recently published by Stein J.D. and co-authors was to characterize the costs of caring for patients with open angle glaucoma (OAG) in the United States and to identify factors that influence these costs. They enrolled claims data from 19,927 newly diagnosed OAG patients in a large managed care network. Data were reviewed to identify glaucoma-related charges for all incident OAG patients from 2001 through 2009. Stein and co-authors found that the costliest 5% of enrollees were responsible for 24% of all glaucoma related charges, while those whose costs fell within the lower 50% of the cost distribution were responsible for 19% of all glaucoma-related charges. A spike in glaucoma-related charges occurred in the six-month period following the time of OAG diagnosis.
Risk factors associated with being in the cost list's 5% included younger age, cataract surgery, ocular comorbidities and Northeastern United States state residence. The main advantage of this study is the large sample size included and that the longitudinal-cohort-study design allowed authors to examine long-term trends in resource use. Overall, the study is very interesting and provides useful data in the field of health economics. However, there are limitations to consider while interpreting the data. The authors claimed that they investigated the pattern of resource use during the first years after disease onset. We must notice here that the time of OAG diagnosis may not be the same as the time of disease onset. OAG patients at diagnosis may have various stages of the disease. Stage of the disease was not included in the analysis since related information was not available in the dataset of this study. More importantly, it has been reported that stage is a factor to consider while evaluating glaucoma care cost. (Lee PP, et al. J Glaucoma 2007; 16(5): 471-478; Traverso CE et al. Br J Ophthalmol 2005; 89(10): 1245-1249). Also, the distribution of glaucoma cases with black patients representing only 8.3% of OAG cases and with a high percentage (75.4%) of OAG cases with household net worth levels of $150000 or more, may indicate that the sample of enrollees in this study may suffer from selec- tion bias with regards to race and socio-economic status. This may limit generalizability of the findings. Finally, one cannot exclude the possibility of miscoding glaucoma suspects, including hypertensives, as OAG patients in this data set, which also could influence the findings. Despite those limitations, the findings by Stein and co-authors have importance for future evaluations of the cost-effectiveness of screening and treatment of glaucoma. Efforts in reducing the glaucoma burden should focus on the small subset of patients who are responsible for a large proportion of all glaucoma-related charges.