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Cost-Effectiveness of Prophylactic Laser Peripheral Iridotomy in Primary-Angle Closure Suspects
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This study evaluated the cost-effectiveness of prophylactic laser peripheral iridotomy (LPI) in primary angle-closure suspects (PACS). A simulation of disease progression in PACS over time, with the projection of costs with and without LPI under a number of different scenarios, showed that LPI prophylaxis was more cost-effective when compared with monitoring alone at 6 years.
- The authors provided a fiscal analysis of the overall cost of monitoring versus LPI for patients. Cost-effectiveness is another factor to consider in the management of PACS.
abstract
This abstract is available on the publisher's site.
Access this abstract nowPurpose
Investigate cost-effectiveness (CE) of prophylactic laser peripheral iridotomy (LPI) in primary angle closure suspects (PACS).
Design
Cost-effectiveness analysis utilizing Markov models
Subjects
Patients with narrow angles (PACS)
Methods
Progression from PACS through 4 states (PAC, PAC glaucoma, blindness, death) was simulated using Markov cycles. The cohort entered at 50 years and received LPI or no treatment. Transition probabilities were from published models and risk reduction of LPI was from the ZAP trial. We estimated costs at Medicare rates and previously published utility values were used to calculate quality-adjusted-life-year (QALY). Incremental cost-effectiveness ratios (ICER) were evaluated at $50,000. Probabilistic sensitivity analyses (PSA) addressed uncertainty.
Main outcome measures
Total cost, QALY, ICER
Results
Over 2 years, the ICER for the LPI cohort was >$50,000. At 6 years, the LPI cohort was less expensive with more accrued QALY. In PSA, the LPI arm was cost-effective in 24.7% of iterations over 2 years and 92.7% over 6 years. The most sensitive parameters were probability of progressing to PAC and cost and number of annual office visits.
Conclusions
By 6 years, prophylactic LPI is cost-effective. Rate of progressing to PAC and differing practice patterns most impacted CE. With uncertainty of management of narrow angles, cost may be a decision management tool for providers.
Additional Info
Disclosure statements are available on the authors' profiles:
Recent randomized controlled trials found that the incidence of primary angle-closure glaucoma (PACG) significantly decreased in eyes treated with prophylactic laser peripheral iridotomy (LPI) compared with fellow untreated eyes. The Zhongshan Angle-Closure Prevention (ZAP) trial revealed that over 6 years, there was a 4% rate of conversion from PAC suspect (PACS) to PAC/PACG. Another similar study, the Singapore Asymptomatic Narrow Angles Laser Iridotomy Study (ANA-LIS) trial, showed that the rate of progression to PAC/PACG from PACS over 5 years was 4.9%. Based on the results of these trials, LPI was not recommended unless there is a high risk of progression to angle-closure disease. Sood et al noted that both studies had a design flaw. Both the ZAP and ANA-LIS trials were conducted on the Asian population. The purpose of the current investigation was to develop “a decision analytic model using Markov cycles to simulate progression from PACS to angle-closure disease and blindness in the US context." Furthermore, the authors "compared the cost-effectiveness of prophylactic LPI in the PACS stage with that of the monitoring/no initial treatment (control arm) using data from the ZAP Trial.” Their results showed that cost-effectiveness began 3 years after prophylactic LPI. This means that “over 2 years, prophylactic LPI was cost-effective in 24.65% of iterations; over 3 years, prophylactic LPI was cost-effective in 54.57% of iterations, and by 6 years, the LPI arm was cost-effective in 92.69% of iterations.”
The strength of their study is the inclusion of the data on the cost of an office visit and testing using gonioscopy, anterior and posterior optical coherence tomography imaging, and the visual field at 6 months, 12 months, and 24 months of patients receiving prophylactic LPI, as well as the non-LPI patients. The authors even included the cost of the postoperative steroidal drops: “Over 50 years, patients receiving prophylactic LPI on entry accrued $12,628 in cost …while those without prophylactic LPI on entry accrued $17,642 in cost… With annual office visits, the LPI intervention became cost-effective after 3 years while with biyearly office visits it became cost-effective after 1-year.”
In contrast to the ZAP and ANA-LIS trials, this superb paper by Sood et al not only demonstrated the cost-effectiveness of prophylactic LPI, but also, over 5-years, its clinical efficacy. The study showed that “within the LPI cohort, 11.7% progressed to PAC…and in the non-LPI cohort, 21.1% progressed to PAC.” More importantly, either annual or biannual visits are options in lieu of a prophylactic LPI in patients with narrow angles who are clinically asymptomatic.