We propose to evaluate the current paradigm for follow-up visits in glaucoma suspects from an economic perspective. The current standard of practice for people with ocular hypertension or other early evidence of glaucoma calls for examinations every 6- 24 months. Most people with ocular hypertension as defined in the Ocular Hypertension Treatment Study (OHTS) (IOP >24 mm Hg) would be considered to be at higher risk of progression to POAG and would be considered for more frequent follow up examination visits (i.e., a 6 month examination visit interval), particularly if they are receiving pressure lowering treatment. Given a prevalence of people with IOP >24 mm Hg of 3-7 million and an average Medicare allowable charge of $138.12 (visit and visual field examination), it follows that this semi-annual testing costs U.S. health care payers $400 million to $1 billion annually. A change in clinical policy to an annual testing regimen could result in savings for heath care payers of $200-500 million. In this proposal, we will examine the consequences of a change in the paradigm for follow-up examination in people with ocular hypertension (i.e., IOP >24 mm Hg) from semi-annual, to annual or bi-annual follow-up visits. We will do this by expanding the OHTS Economic Model to allow comparison of the cost-effectiveness of three strategies (i.e., a 6-month examination interval, a 12 month examination interval, and a 24-month examination interval). To evaluate the probability of a delay in treatment due to an expanded examination interval, we will use data collected from OHTS participants. OHTS was a randomized treatment trial of the safety and efficacy of IOP lowering therapies for the prevention of primary open angle glaucoma (POAG). The study began enrolling participants in 1994 (n=1,636) and had a median follow of 78 months at the time results were reported in 2002. During the first 78 months of follow-up (median) 44 participants developed a visual field end point, 69 an optic disc endpoint, and 12 developed both. In these analyses will we will rely primarily on information from the observation arm. Evidence from the trial will be used to determine the probability of a delay in diagnosis of an incident case of POAG. This will be calculated by estimating the proportion of POAG incident cases that would be """"""""missed"""""""" due to less frequent follow-up examination visits. The consequences of a delay in case identification will be weighed against the cost savings from less frequent office visits and procedures by incorporating the probability of the delay into the OHTS Economic Model. We will use cost-utility and cost benefit approaches to estimate cost-effectiveness. The perspective taken in these analyses will be societal (where we will use cost-utility analysis) and the payer (where we will use cost-benefit analyses). Conducting sensitivity analyses with this decision model will permit evaluation of the consequences of a delay in case identification beyond the characteristics of the OHTS sample.
The current standard of practice for people at higher risk of developing glaucoma calls for follow-up examination visits every six months. We estimate that the cost of U.S. health care payors from this policy approaches $1 billion, yet this policy has never been evaluated empirically. In this study, using data from the Ocular Hypertension Treatment Study (OHTS) and the OHTS Economic Model we use a decision analytic approach to compare the costs and benefits of three follow-up examination intervals: 6-month, 12 month, and 24 month.
