Macular optical coherence tomography improves cost-effectiveness of screening for diabetic macular edema

Abstract

Purpose: To compare the cost-effectiveness of four different screening strategies to detect diabetic macular edema Study Design: Subjects are recruited from a local screening program during February 2014 to January 2016. The current screening protocol, Strategy A, was compared with three other alternative screening strategies using a simulation model. In Strategy B, retinal hemorrhage involving the macula is no longer considered a surrogate marker for DME; Strategy C utilizes best corrected visual acuity instead of presenting visual acuity and macular optical coherence tomography (OCT) for suspected DME cases; and Strategy D adds macular OCT for all cases to the current screening protocol. Methods: In addition to the current screening protocols, best-corrected visual acuity assessment (BCVA) and a macular volume scan using optical coherence tomography (OCT) (Cirrus HD OCT 4000, Carl Zeiss Meditec, Dublin, California, USA) were added to the screening routine for all study subjects. The 4 strategies were compared in terms of the sensitivity indexes, health benefits, i.e. quality-adjusted-life-years (QALYs) gained, and the cost-effectiveness. Reference for comparison was taken from the gross domestic product per capita (GDP) of Hong Kong, as well as USD$50,000/QALY gained. When using Hong Kong's GDP as reference, strategies costing: 1) less than 1 GDP are considered ‘very cost-effective’;2) between 1 to 3 times the GDP are considered ‘cost-effective’;3) more than 3 times the GDP are considered ‘not cost-effective’. The GPD of Hong Kong from 2014 was used (HKD$310,113, or USD$39,963) as the reference. Results: A total of 2,277 subjects (mean age 62.80±11.75 years, 43.7% male) were recruited. With OCT used as a standard for identifying DME, the false-positive rate of DME using Strategy A and B was 87.1% and 79.8%, respectively. The cost of Strategies A, B, C, and D, in terms of USD$/QALY gained, was 7447.5, 8428.7, 5992.3 and 4113.5, respectively. All 4 strategies were considered ‘very cost-effective’ when using both Hong Kong’s gross domestic product per capita (GDP) and <USD$50,000 per QALY gained as references. Conclusions: Although the current screening protocol can still be considered as cost-effective, the high false-positive rate of DME would lead to an excessive amount of unnecessary specialist referrals. In contrast, Strategy D, by incorporating OCT for all subjects into the current protocol, was found to be the most cost-effective screening strategy.