Considering a reasonable WTP threshold , intermediate dose statin therapy is economically attractive , and should be a priority intervention in prevention of cardiovascular events in Brazil
BACKGROUND Statins have proven efficacy in the reduction of cardiovascular events , but the financial impact of its widespread use can be substantial .
OBJECTIVE To conduct a cost-effectiveness analysis of three statin dosing schemes in the Brazilian Unified National Health System ( SUS ) perspective .
Cost-Effectiveness of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitor Therapy in Older Patients with Myocardial Infarction
Recent large-scale r and omized , controlled trials of 3-hydroxy-3-methylglutaryl coenzyme A ( HMG-CoA ) reductase inhibitors ( statins ) have shown statistically significant reductions in cardiovascular events , strokes , and total mortality among selected groups , including patients with risk factors for vascular disease or a history of vascular disease ( 1 - 5 ) . In addition , cost-effectiveness analyses of the Sc and inavian Simvastatin Survival Study and the West of Scotl and Coronary Prevention Study have shown favorable cost-effectiveness ratios ( 6 , 7 ) . A limitation of the r and omized , controlled trials of statin therapy published to date , however , has been their failure to enroll patients older than 75 years of age . Ongoing r and omized , controlled trials are including patients in this age category , but results will not be available for some time ( 8 , 9 ) . Meanwhile , analyses of data from two secondary prevention trials , the Sc and inavian Simvastatin Survival Study and the Cholesterol and Recurrent Events ( CARE ) trial , have found that participants 65 to 70 years of age and those 65 to 75 years of age , respectively , experienced statistically significant reductions in cardiac end points similar to those seen in trial participants as a whole ( 10 , 11 ) . These results raise the prospect of extending the use of statins to patients older than 75 years of age with established coronary heart disease ( 12 ) . Although the issue of efficacy in patients older than 75 years of age will not be resolved definitively until trials of patients in this age group are published , decision-analytic models can test various assumptions about efficacy to gauge the potential cost-effectiveness of statins in this context . We modeled the cost-effectiveness of  statin therapy in a hypothetical cohort of patients 75 to 84 years of age with a history of myocardial infa rct ion by extrapolating results from published r and omized , controlled trials and epidemiologic data . Methods Model We compared two strategies for patients 75 to 84 years of age with previous myocardial infa rct ion :  usual care and initiation of HMG-CoA reductase inhibitor therapy . We developed a Markov model ( 13 ) and conducted a cohort simulation to track costs and health outcomes for hypothetical patients r and omly assigned to one of these strategies . In this model , patients can occupy one of six health states : baseline ( history of at least one myocardial infa rct ion ) , recurrent myocardial infa rct ion , postrecurrent myocardial infa rct ion , stroke , post-stroke , or dead ( Figure 1 ) . The model was not configured to deal with multiple events ( such as recurrent myocardial infa rct ion after stroke ) because such sequences of events occur infrequently enough to have a small effect on the overall analysis . Other health states , such as congestive heart failure , were not modeled explicitly but were averaged into the mortality estimates and quality -of-life weights . The model was constructed by using DATA 3.5 software ( TreeAge Software , Williamstown , Massachusetts ) . We adopted the societal perspective in all analyses . Figure 1 . Markov model . MI Transition Probabilities Each state of the model has an associated mortality rate that specifies the probability of dying in any given cycle ( Table 1 ) . These mortality rates were determined by using mortality risk ratios relative to all-cause mortality for an age-matched unselected population ; all-cause mortality rates were obtained from vital statistics data ( 14 ) . We chose to use mortality risk ratios ( multiplicative model ) rather than excess mortality ( additive model ) because a multiplicative model better captures how the risk for death from coronary heart disease changes with age ( 15 , 16 ) . Table 1 . Variables Governing Transition Probabilities for the Markov Model For purpose s of calibration , we initially created a two-state ( alive or dead ) Markov model , with mortality rates based on the 10-year survival curve after acute myocardial infa rct ion for patients 75 to 84 years of age ( 17 ) . The life expectancy of patients in the calibration model was then used as a benchmark to calibrate life expectancy for patients in the usual care strategy of the full six-state model . In the six-state model , we differentiated between death after recurrent myocardial infa rct ion or stroke and death from nonmyocardial infa rct ion or nonstroke causes because statins , by preventing both myocardial infa rct ion and stroke ( 2 ) , also prevent death after these events . Because patients with a history of myocardial infa rct ion have a higher chance of dying of coronary heart disease that is unrelated to recurrent myocardial infa rct ion ( for example , arrhythmia ) , this cohort has a higher risk for death from causes other than myocardial infa rct ion or stroke than does an unselected population . Long-term mortality after recurrent myocardial infa rct ion was adjusted upward to account for the additional risk for death after a recurrent event , on the basis of hazard ratios for coronary heart disease death as a function of nonfatal reinfa rct ion ( 18 ) . We converted these ratios into a hazard ratio for total mortality on the basis of data from the same trial indicating that coronary heart disease caused 76 % of deaths ( 19 ) and on the assumption of no excess risk for noncoronary heart disease death in patients with reinfa rct ion . Mortality rates after stroke were based on published data from the Oxfordshire Community Stroke Project ( 20 ) . Transition probabilities to recurrent myocardial infa rct ion or stroke from the baseline state are based on data describing reinfa rct ion rates ( 21 ) and stroke rates ( 22 , 23 ) . All of the data used to determine transition probabilities are population -based and specific to patients older than 75 years of age , with the exception of data from a clinical trial of patients up to 75 years of age ( 18 , 19 ) . We used data from a follow-up study of patients 65 to 75 years of age in the CARE trial to estimate the relative risk reduction conferred by statin therapy for the end points of myocardial infa rct ion ( fatal and nonfatal combined ) and stroke ( 11 ) . This study stratified patients in the CARE trial into those younger than 65 years of age and those 65 to 75 years of age and found that the latter group experienced statistically significant and clinical ly important reductions in cardiac and cerebrovascular events . Our base-case analysis used the mean estimates of relative risk reduction published in this study for patients 65 to 75 years of age , and the sensitivity analysis used the 95 % confidence limits . We applied risk reductions due to statin therapy to only two transitions out of the baseline state : recurrent myocardial infa rct ion and stroke . Because we did not explicitly model multiple strokes or recurrent myocardial infa rct ion , the model is based on the assumption that patients discontinue statin therapy after their first stroke or recurrent myocardial infa rct ion and no longer experience any additional costs or benefits of statin therapy . We also assumed that patients in the baseline state who are receiving statin therapy continue to accrue the benefits and costs associated with this therapy for the duration of their time in the baseline state . In a sensitivity analysis , we limited benefits of statin therapy to the first 5 years in the baseline state ; this time frame is similar to the duration of follow-up for the large r and omized , controlled trials of statin therapy ( 1 - 5 ) . Under this scenario , after 5 years , patients experience the same event rates and mortality rates as those not using statin therapy but continue to accrue the costs of drug while in the baseline state . This conservative analysis was conducted to examine the consequences of continuing to take a drug that in fact provides no additional benefit beyond the period for which it has been studied . Health-Related Quality of Life The model measured health effects in terms of quality -adjusted life expectancy . The health-related quality -of-life weights for the health states ( Table 2 ) were derived from time-tradeoff scores collected from patients with myocardial infa rct ion in the quality -of-life sub study of Global Use of Strategies to Open Occluded Coronary Arteries ( GUSTO-I ) ( 24 ) , which included patients older than 75 years of age . That study reported quality -of-life scores in patients who experienced various levels of disability from in-hospital stroke after myocardial infa rct ion and in patients who did not have a stroke . The quality -of-life weight ( utility ) for stroke was derived from the mean time-tradeoff utility for patients with ischemic stroke in GUSTO-I because these represent most nonfatal strokes . Bounds for sensitivity analysis were based on quality -of-life estimates approximately 1 SD from the mean . We also conducted a sensitivity analysis in which health states were not adjusted for quality -of-life differences . Table 2 . Utilities , Costs , and Discount Rate The base-case model assumed no disutility associated with statin use . This assumption was based on two studies of pravastatin that included patients older than 75 years of age and showed that pravastatin was well tolerated , with an incidence of adverse events similar to that of placebo ( 25 , 26 ) . However , because we know of no published studies of utilities in patients receiving statins , we performed a sensitivity analysis using a utility decrement of 0.013 in patients taking statins  . This number represents the utility decrement related to taking warfarin , a drug associated with considerably more inconvenience ( monthly laboratory monitoring ) , lifestyle modification , and risk than statins ( 27 ) . Costs In the base-case model , we included the following direct medical costs for both strategies : hospitalizations for nonfatal and fatal myocardial infa rct ion , hospitalizations for stroke , and post-stroke institutional care ( nursing home and rehabilitation ) . Patients in the  statin  group also experienced yearly drug costs and the cost of two additional office visits and two hepatic function
Considering a reasonable WTP threshold , intermediate dose statin therapy is economically attractive , and should be a priority intervention in prevention of cardiovascular events in Brazil
BACKGROUND Statins have proven efficacy in the reduction of cardiovascular events , but the financial impact of its widespread use can be substantial .
OBJECTIVE To conduct a cost-effectiveness analysis of three statin dosing schemes in the Brazilian Unified National Health System ( SUS ) perspective .