Are Intensive Lipid-lowering Regimens an Optimal Economic Strategy in Patients with ACS? An Acute and Chronic Perspective

Roberta Ara; Rachid Rafia; Sue E Ward; Anthony S Wierzbicki; Tim M Reynolds; Angie Rees; Abdullah Pandor

Disclosures

Expert Rev Pharmacoeconomics Outcomes Res. 2009;9(5):423-433. 

In This Article

Comparing the Published Results

Number of Events Modeled

Chan used a starting age of 60 years and presented the numbers of events (Table 5) predicted for cohorts of 1000 patients during a 30-year horizon, while Guideline and Ara used starting ages of 65 and 60 years of age and presented the numbers of events predicted for time horizons of 35 and 40 years of age, respectively.[3,4,105] The numbers of fatal cardiovascular events predicted in Guideline's and Ara's models were similar. Guideline predicted 389 for the low-dose strategy (assumed equivalent to simvastatin 20 mg/day) while Ara predicted 380 for the simvastatin 40 mg/day arm. Similarly, where Guideline predicted 333 fatal cardiovascular events for the intensive-dose regimen (equivalent to simvastatin 80 mg/day or atorvastatin 80 mg/day), Ara predicted 359 for the simvastatin 80 mg/day arm and 320 for the atorvastatin 80 mg/day arm. When using a lifetime horizon, all individuals die eventually, whether this is related to the condition modeled or some other cause. In Chan's evaluation, the total number of fatal events avoided during the first 30 years of the model was 13, while in Guideline's and Ara's the total number was one, as the fatal cardiovascular events avoided were offset by the nonvascular deaths. This large difference can be explored by the fact that Chan applied the ACM RR to all deaths whereas the others restricted benefits to CVD fatal events.

The total number of nonfatal MIs in each arm in Chan's model was much smaller than in the other two models. Conversely, the absolute and incremental revascularization procedures were much larger in Chan's model compared with Guideline's (Chan incremental: 135; Guideline incremental: 12). Also of note is the large difference in the number of nonfatal strokes predicted. Chan and Guideline predicted 133 and 112, respectively, in the low-dose arm while Ara predicted just 55 for simvastatin 40 mg/day. Chan modeled a constant rate to the nonfatal stroke health state irrespective of history or age. Consequently, one would expect there to be a difference in the numbers predicted when compared with Ara's, where transitions to the stroke health state depended on age, history of cardiovascular condition and time since the previous event.

QALYs, Costs & Incremental Cost–Effectiveness Ratios

The incremental QALY gains ranged from 0.11[4] to 0.35 (Table 6)[3] and the incremental costs ranged from £597 in the UK[4] to £3154 in the USA.[3] The absolute QALYs and the absolute costs were much higher in Chan's model than in the other two. The baseline incremental cost–effectiveness ratios ranged from £4397[105] to £17,469.[4]

Sensitivity Analyses

All three studies conducted full probabilistic sensitivity analyses. Chan reported that 95% of results would be considered cost effective at a threshold of US$31,000 per QALY.[3] Their model was sensitive to the incremental difference in costs of statins and the sustained efficacy of the high-dose statins beyond the duration of the clinical studies. It is worth noting that in the ACS evaluation 86% of the QALY gain was due to reductions in ACM. Guideline reported that 94% of base case results fell below a £20,000 per QALY threshold, and that if the high-dose statin was priced as generic simvastatin, the low-dose regimen dominated (i.e., smaller costs and higher costs than the higher dose regimen).[105] When assessing the net benefits of the four alternative treatments, Ara reported that rosuvastatin 40 mg/day would be considered the optimal treatment under current prices for statins.[4] However, when exploring the effect of potential future reductions in the cost of atorvastatin 80 mg/day, they found this treatment would be the most cost-effective alternative.[4]

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