At what risk of developing POAG is it cost-effective to treat patients with ocular hypertension? Kymes et al. (608) address this issue in an economic analysis based on the Ocular Hypertension Treatment Study. A Markov-model was constructed with states for ocular hypertension, POAG in HAP stages 1-5, bilateral Health economics blindness and death. Costs, from a societal perspective, and utilities (values relating to quality of life) were assigned to each state based on US sources. Four strategies were examined: treating no-one before onset of POAG, treating patients with annual risk of developing POAG ≥ 5%, treating patients with annual risk ≥ 2% or treating everyone with IOP ≥ 24 mmHg.
Under base-case assumptions, treating all patients was not cost-effective compared to no treatment, with an incremental cost per quality-adjusted life years (QALY) of around US$145,000. Contrary to this, treating only patients with a ≥ 5% risk resulted in a cost per QALY of US$3670, while a risk of ≥ 2%, treatment was associated with a cost per quality-adjusted life-year (QALY) gained of US$42,430 compared to treating patients with ≥ 5% risk, and around US$29,000 compared to no treatment. This was judged as cost-effective by the authors, assuming a value of US$75,000-$100,000 per QALY.
Costeffectiveness data for treatment of patients with ocular hypertension provide important information for the management of glaucoma, provided assumptions on risk assessment in the individual patient are correctWhile this model addresses a key question, several issues are worth discussing:
gression of POAG (HAP stages) or utilities are based on relatively limited data sets.
However, the study illustrates nicely the crucial importance of targeting patients groups with the highest potential to benefit from treatment in order to optimize the use of health care resources.
Linus Jönsson is Managing Director European Health Economics, Stockholm, Sweden and has a PhD Health Economics from the Karolinksa Institute, Stockholm, SwedenEditors' comment:
It is well known and unfortunate that compliance, adherence and persistence are far from ideal in the real world. The outcome of the OHTS is of course the ideal world. The authors could have modified their calculations and subsequently their conclusions based on a diminished effect of treatment due to the abovementioned issues.
When to treat is the topic of an ongoing discussion. As the authors mention the question is often whether to treat Ocular Hypertension or to wait for the earliest conversion. The current study does not address this question; it is however possible to carry out a cost-effectiveness study on that question. The experts in the field are encouraged to do so.