Adjunctive lamotrigine therapy in patients with refractory seizures: a lifetime cost-utility analysis

OBJECTIVE

Lamotrigine as add-on treatment (500 mg per day) is effective in patients with refractory epilepsy, but its high cost requires a pharmacoeconomic analysis. We conducted a retrospective lifetime cost utility study in which clinical data were derived from a recent placebo-controlled clinical trial, cost-of-illness data were drawn from a previous ad-hoc study, and quality-of-life values were obtained by prospectively interviewing a separate group of 81 patients referred to our institution with epilepsy.

RESULTS

Our analysis showed that chronic lamotrigine treatment implies an incremental lifetime cost of about $1,600,000 for every 100 patients. Incremental lifetime utility was around 40 quality-adjusted life-years (QALYs) for every 100 patients. On the basis of these data, adjunctive lamotrigine was estimated to cost approximately $41,000 per QALY gained. Sensitivity testing suggested a range of $25,000-$85,000 per QALY gained.

CONCLUSION

Adjunctive lamotrigine (500 mg per day) in refractory epilepsy seems to have a worse pharmacoeconomic profile than many pharmacological treatments commonly used in areas other than epilepsy. Further data are needed to determine if lamotrigine can be equally effective at lower (and less costly) daily doses which could markedly improve its pharmacoeconomic characteristics.

Lamotrigine update and its use in mood disorders

OBJECTIVE

To provide a qualitative, systematic update and review of the pharmacology, pharmacokinetics, efficacy in mood disorders, adverse effects, and costs of lamotrigine.

DATA SOURCES

Citations obtained from MEDLINE searches (1985-September 2001) using lamotrigine as a text word, articles identified in reference lists of pertinent articles, abstracts presented at conferences, and research data from GlaxoSmithKline.

DATA EXTRACTION

English-language articles were considered for possible inclusion. Each title and abstract was examined to determine whether the publication contained up-to-date information relevant to the objective. Twenty clinical trials that provided data on response rates in mood disorders were tabulated.

DATA SYNTHESIS

Lamotrigine's primary action is to modulate voltage-gated sodium channels. Evidence suggests that it decreases glutamate transmission, directly reduces calcium influx, mildly blocks transmitter reuptake, and alters intracellular mechanisms of resting transmitter release. The average half-life of lamotrigine is approximately 24 hours, but decreases to approximately 7.4 hours when used concurrently with phenytoin, and increases to approximately 59 hours with valproic acid. Seven of the 20 clinical trials were randomized, double-blind, and controlled. Existing data are inadequate to evaluate lamotrigine use in major depression. The pooled response rates for patients with depressed, manic, mixed, and rapid cycling bipolar disorder were similar, ranging from 52% to 63%. Adverse effects are infrequent when the drug is used alone, but become more frequent when lamotrigine is combined with other anticonvulsants. While most rashes are mild, approximately 1 in 500 patients develops exfoliative dermatitis. A slow upward dose titration is recommended to reduce the incidence of serious rash, but this may delay the attainment of adequate dosage for 6 weeks. Lamotrigine has positive effects on cognitive function, but occasionally produces insomnia. Lamotrigine costs 2-4 times more than lithium, carbamazepine, and generic valproic acid.

CONCLUSIONS

When efficacy, adverse effects, and cost are considered, lamotrigine should probably be reserved as a second-line agent for bipolar depression.

Cost-effectiveness model of adjunctive lamotrigine for the treatment of epilepsy

OBJECTIVE

To predict the cost-effectiveness of lamotrigine by evaluating the costs and health outcomes in treated patients.

BACKGROUND

Lamotrigine adjunctive therapy has been found to be associated with decreased seizure frequency and severity in patients who are refractory to treatment with the older antiepileptic drugs (AEDs).

METHODS

We used a cost-effectiveness clinical decision analysis framework to assess the impact of these clinical benefits on patient health care use. The measure of effectiveness was seizure-free days gained. The measures of health care resource use included hospitalizations, outpatient and emergency department visits, surgery, and AEDs. Medical care use and cost estimates were derived from clinical trial data and published sources. Costs and effectiveness (incremental costs per seizure-free days gained) of lamotrigine adjunctive therapy versus older AEDs were compared in patients refractory to previous treatment during three time periods: the start-up year, the second year when decisions about surgery were made, and all subsequent years.

RESULTS AND CONCLUSIONS

The model predicts that use of lamotrigine would be associated with an overall reduction in use of other direct medical care resources (hospitalizations, outpatient visits, diagnostic and laboratory tests, and surgery). For a 10-year time horizon, the estimated cost-effectiveness ratio is $6.9 per seizure-free day gained. The model provides a flexible framework to analyze the effect of new antiepileptic drugs.

The economic consequences of generic substitution for antiepileptic drugs in a public payer setting: the case of lamotrigine

Generic substitution of antiepileptic drugs (AEDs) may increase pharmacy utilization, thus counterbalancing per-pill savings. The purpose of our study was to analyze the economic impact of government-mandated switching from branded to generic lamotrigine. Patients in a Canadian public pharmacy claims database using branded lamotrigine (Lamictal GlaxoSmithKline, UK) in 2002 converted to generic lamotrigine in 2003 and were observed from July 2002 to March 2006. Patients used branded lamotrigine for >or=90 days pre-generic entry and had >or=1 claim for generic lamotrigine post-generic entry. For the generic period, observed per-patient monthly drug costs were calculated as the sum of costs for lamotrigine, other AEDs, and non-AEDs. Expected per-patient drug costs were estimated assuming lamotrigine dose and other prescription drug utilization in the generic period were identical to those observed during the brand period. Differences between observed and expected costs were compared. Among 1,142 branded lamotrigine users, overall average monthly drug costs per person were expected to decrease by $30.55 due to lower pill costs. Instead, they fell by $11.98 from the brand to the generic periods (p < 0.001). Because of dosage changes, lamotrigine costs decreased by $29.92 instead of the anticipated $33.87 (p < 0.001). Increased pharmacy utilization caused other AED costs to rise by $6.29 versus the expected $0.36 (p < 0.001), while non-AED drug cost increased by $11.64 rather than by $2.95 (p < 0.001). We concluded that conversion to generic lamotrigine resulted in lower than expected cost savings. Further research is necessary to determine whether this is due to reduced effectiveness and/or tolerability. Payers may weigh smaller-than-expected cost reductions against a possible decrease in effectiveness to assess the relevance of mandatory generic switching of lamotrigine.

Adjunctive therapy in epilepsy: a cost-effectiveness comparison of two AEDs

The objective of this study was to compare the relative cost-effectiveness of two AEDs by a prospective clinical audit. Patients starting on the adjunctive therapies lamotrigine and topiramate were recruited from the out-patient epilepsy clinics at Queen Square. Three interview were scheduled: baseline; three months follow-up and six months from baseline. Of the 81 patients recruited, a total of 73 patients completed all three interviews. An intention to treat analysis was performed on the data. Seizure severity and frequency were assessed using the National Hospital Seizure Severity Scale. Side-effects, adverse events and reasons for stopping medication were also recorded. At the third interview, a total of 47/73 (64%) were still on the prescribed adjunctive drug. Outcome was assessed by two methods: the > 50% seizure reduction cited in the literature and a more stringent assessment of patient 'satisfaction' which we defined operationally on clinical criteria. Using this definition, a total of 10/73 (14%) patients were 'satisfied'. The relative costs of starting patients on each of the two AEDs were calculated, both drug costs and the costs of adverse events (the latter were defined as events requiring urgent medical attention). The costs of the two drugs were compared. A number of methodological issues relating to cost comparison are discussed. Outcome and pharmaco-economic studies need to assess more than reduction in number of seizures. They should take into account variables important for quality of life including side-effects and adverse events.

Effects of toltrazuril on the growth of piglets in herds without clinical isosporosis

Isospora suis is a widely prevalent and economically important parasite. The antiprotozoal compound, toltrazuril, was given as a single treatment to piglets without clinical signs in 10 herds. The daily weight gain (DWG) and mortality between the treatment date and weaning was compared on each herd in 10 treated and 10 control litters. The faeces of control litters were examined for oocyst excretion. In six herds, no oocysts were detected and treatment had no effect on DWG or mortality. In four pig herds, oocysts were detected and toltrazuril treatment significantly improved DWG by 25 g (P=0.003). Mortality rate was not affected. The partial economic benefit of toltrazuril treatment in positive herds was 0.20 euros per piglet. A single toltrazuril treatment of piglets in herds without clinical signs of isosporosis but with oocysts detected significantly improved DWG and was considered economically justified on each farm.

The cost-effectiveness of lamotrigine in the maintenance treatment of adults with bipolar I disorder

OBJECTIVE

To present an economic model and cost-effectiveness estimates for lamotrigine in maintenance treatment of bipolar I disorder (BD-I) using outcomes from the pivotal lamotrigine trials. The main comparator treatments in the pivotal trials were lithium and .no maintenance. (acute-only) treatment. A comparison with olanzapine was included as an indirect analysis following publication of data during the course of our research.

METHODS

A Markov model was built around the 3 health states of euthymia, mania, and depression. The base-case model simulates a cohort of 1,000 patients with BD-I who have recently stabilized after resolution of a bipolar mania episode. The cohort was modeled for a period of 18 months. Resource-use estimates were derived from best available published data, treatment guidelines, a physician survey, and published unit cost data. Outputs were measured in terms of costs per acute mood episode avoided, costs per euthymic day gained, and costs per quality-adjusted life-years (QALYs). Direct health care payer costs are used in the analyses.

RESULTS

The base-case model for patients with a recent manic episode indicated that lamotrigine is the most effective treatment for avoiding both acute depression episodes and all types of acute episodes (depression and mania). It is also the most effective treatment in terms of number of euthymic days achieved (309 days per patient per year). Olanzapine is most effective for avoiding acute mania episodes. Total direct costs of treatment are lowest for the lithium treatment arm (Dollars 8,710 per patient for the 18-month period). All maintenance therapies were cost effective compared with the no-maintenance (acute-only treatment) arm. In the base case, lamotrigine had incremental cost-effectiveness ratios of Dollars 30 per euthymic day and Dollars 2,400 per acute episode avoided compared with lithium. A QALY analysis indicated that lamotrigine is cost effective in patients with a recent manic episode at Dollars 26,000 per QALY. The base-case model indicated that lamotrigine dominates olanzapine, (that is, lamotrigine costs less and is more effective than olanzapine) in patients with a recent manic episode. In a sensitivity analysis using outcomes from the pivotal trial of recently depressed patients, lamotrigine, in comparison with lithium, was not shown to be as cost effective as in the recently manic patients, but it was still cost effective compared with no maintenance treatment.

CONCLUSIONS

For a defined cohort of patients with BD-I, the pharmacoeconomic model indicated that prevention of mood episodes with lithium and lamotrigine is cost effective in patients with a recent manic, mixed, or hypomanic episode. The conclusions with respect to the indirect comparison with olanzapine should be validated if and when direct trial data become available. Cost-effectiveness of maintenance treatments for patients with BD-I (recently depressed as well as recently manic) are likely to improve in models with a broader costing perspective and that take a longer time frame. Further research into the outcome implications of health-related quality of life and other BD subgroups are recommended.

Economic benefits of prophylaxis with diclazuril against subclinical coccidiosis in lambs reared indoors

One hundred and twenty weaned male lambs, naturally infected with Eimeria species, were used to assess the economic benefits of the prophylactic administration of diclazuril. They were randomly divided into four groups of 30 lambs on the basis of their bodyweight and output of oocysts. The groups were either left untreated (group 1), treated orally with a simple dose of diclazuril at 1 mg/kg (group 2), with two doses two weeks apart (group 3), or with sulphadimethoxine at 50 mg/kg for five consecutive days (group 4). No clinical signs of coccidiosis were observed in any of the groups. The output of oocysts was significantly reduced on day 7 after treatment in group 2, on days 7, 14 and 28 in group 3 and on days 7 and 14 in group 4. No significant differences were found between the treated and untreated groups for bodyweight, carcase weight and carcase classification. The mean fattening period was shorter for the treated lambs (52 and 55 days) than for the untreated controls (60 days). The average growth rate of the lambs treated twice with diclazuril and with sulphadimethoxine was improved and the feed conversion rates of the lambs treated once or twice with diclazuril were 7 per cent and 16 per cent better than that of the untreated lambs.

A cost minimization study comparing vigabatrin, lamotrigine and gabapentin for the treatment of intractable partial epilepsy

Epilepsy is one of the commonest of the serious neurological disorders. The total economic burden of epilepsy in the United Kingdom has been estimated to be 1930 m pounds, with around 32 m pounds spent on antiepileptic drug therapy alone. Despite the high level of expenditure on drug therapy for epilepsy there is very little information regarding the relative cost-effectiveness of the different drugs available. It is important to establish the relative cost-effectiveness of therapies to provide decision makers with the information necessary to allocate resources in a rational manner and thus achieve the highest benefit for available resources. In this study the cost-effectiveness of lamotrigine, vigabatrin and gabapentin was estimated by a cost minimization analysis for the first year of drug therapy using data based on published studies. In general, there was little difference between the initial direct costs of treatment, however, the fewer side-effects associated with gabapentin is reflected in the lower total costs of treatment in the first year resulting in savings of 18.52 pounds per patient compared with lamotrigine and 47.18 pounds compared with vigabatrin. Based on incidence data estimates this translates to estimated direct cost savings to the UK of between 166,680 pounds and 424,620 pounds per annum.

Economic impact of generic substitution of lamotrigine: projected costs in the US using findings in a Canadian setting

BACKGROUND

Generic substitution may not always save health care costs for antiepileptic drugs (AED).

OBJECTIVE

(1) To examine the economic impacts of generic substitution of lamotrigine in Canada; and (2) to convert observed Canadian costs to a United States (US) setting.

METHODS

Health claims from Québec's health plan (RAMQ) between 08/2002 and 07/2006 were analyzed. Patients with > or = 1 epilepsy claim and treated with branded lamotrigine (Lamictal) before generic entry were selected. Health care costs ($/person-year) were compared during periods of branded and generic use of lamotrigine. Two cost-conversion methods were employed; one using purchasing power parities, US/Canada service use ratios, and exchange rate, and another employing Canadian health care utilization and US unit costs.

RESULTS

671 patients were observed during 1650.9 and 291.2 person-years of branded and generic use of lamotrigine, respectively. The generic-use period was associated with an increase in overall costs (2006 constant Canadian dollars) relative to brand use (C$7902 vs. C$6419/person-year; cost ratio (CR) = 1.22; p = 0.05), despite the lower cost of generic lamotrigine. Non-lamotrigine costs were 33% higher in the generic period (p = 0.013). Both conversion methods yielded increases in total projected health care costs excluding lamotrigine (2006 constant US dollars) during the generic period (Method 1: cost difference: US$1758/person-year, CR = 1.33, p = 0.01); Method 2: cost difference: US$2516, CR = 1.39, p = 0.004).

LIMITATIONS

Study limitations pertain to treatment differences, indicators used for conversion and possible claim inaccuracies.

CONCLUSION

Use of generic lamotrigine in Canada was significantly associated with increased overall medical costs compared to brand use. Projected overall US health care costs would likely increase as well.

Adjunctive therapy in epilepsy: a cost-effectiveness comparison of alternative treatment options

A pharmaco-economic study of the administration of adjunctive therapy in patients with chronic epilepsy is described. A decision-analytic model has been used, which represents the consequences of treatment over a 1-year time period, when one of three drugs is used first. The cost-effectiveness ratio for clobazam, lamotrigine and vigabatrin have been calculated. The expected cost per patient of treatment over the 1-year period was up to 50% higher with vigabatrin and lamotrigine compared with clobazam, with a cost-effectiveness ratio around 40% higher.

Choosing a First Drug Treatment for Epilepsy after SANAD: Randomized Controlled Trials, Systematic Reviews, Guidelines and Treating Patients

The ILAE treatment guidelines for initial monotherapy emphasise the poor quality of information available to inform everyday clinical practice. Industry sponsored studies comparing antiepileptic drugs answer restricted licensing questions, rather than those relevant to the clinical community (patients, health professionals and founders of health care). The SANAD study, a pragmatic randomized clinical trial, offers a methodology to address some of these questions. It identifies lamotrigine as a cost-effective alternative to carbamazepine for the treatment of focal epilepsies, but confirms valproate as the most effective drug for the treatment of generalized or unclassified epilepsy.

Economic analysis of epilepsy treatment: a cost minimization analysis comparing carbamazepine and lamotrigine in the UK

New anti-epileptic drugs differ from existing standard therapies not in their clinical efficacy, but in their side-effects profiles. To determine the relative economic value of these agents, one must compare drug costs, costs of resources employed in the management of adverse events, and costs associated with therapeutic switching. In this economic analysis, carbamazepine (CBZ) and lamotrigine (LTG) are evaluated in monotherapy treatment of partial and/or general tonic-clonic seizures in the UK. Adverse event and tolerability data are obtained from a published randomized controlled trial of CBZ vs. LTG. A Delphi panel of clinicians advised treatment patterns for adverse events. Cost data are obtained from public sources. Results show that CBZ therapy costs about one-third of LTG therapy (pound sterling 179 for CBZ vs. pound sterling 522 for LTG) even after the costs associated with the management of adverse events and therapeutic switching are considered.

The cost effectiveness of rufinamide in the treatment of Lennox-Gastaut syndrome in the UK

Lennox-Gastaut syndrome (LGS) is a catastrophic childhood form of epilepsy. The syndrome is characterized by mental impairment, frequent seizures of multiple types that are particularly resistant to treatment, and high rates of seizure-related injury. With the introduction of newer, but more costly, antiepileptic drugs (AEDs), it is important that decision makers are able to assess their value in the management of this rare and difficult-to-treat condition. To evaluate the cost effectiveness, from the UK NHS perspective, of rufinamide in patients with LGS. An individual patient-simulation model was developed to estimate the total treatment-related costs and clinical benefits of rufinamide compared with topiramate and lamotrigine over a 3-year time horizon. The model examines the treatment scenarios of adding rufinamide, lamotrigine or topiramate to older AEDs (standard therapy), or standard therapy alone within a primary-care or community setting. Three placebo-controlled clinical trials of adjunctive AED treatment for children with LGS were analysed. There are no head-to-head comparator studies. Between 98 and 139 patients were randomized in each study and the mean age in each study was 10, 11 and 14 years. A mixed-treatment comparison using a random-effects model was carried out on the number of patients in each response category, using the placebo arms of the respective trials. The primary outcome measure was the percentage of successfully treated patients, defined as >50% reduction in the frequency of total seizures and drop attacks. The hypothesis being tested was formulated after data collection. Costs ( pound, year 2006/07 values) of patient monitoring, switching treatments, hospitalization due to seizure, treatment of adverse effects, and personal and social services were included in the analysis. Results of 10,000 Monte Carlo simulations were bootstrapped to conduct probabilistic sensitivity analysis. Over 3 years, adjunctive rufinamide resulted in higher total costs than topiramate and lamotrigine; however, with more patients being treated successfully, this leads to acceptable incremental cost-effectiveness ratios. If society is prepared to pay at least 250 pounds for a 1% increase in the number of successfully treated LGS patients, in terms of a 50% reduction in the frequency of drop attacks, the probability of the treatment with rufinamide being cost effective is >80%. This cost-effectiveness analysis suggests that rufinamide results in more LGS patients being treated successfully at a reasonable cost from a UK NHS perspective.

Cost effectiveness of adjunctive quetiapine fumarate extended-release tablets with mood stabilizers in the maintenance treatment of bipolar I disorder

BACKGROUND

Bipolar I disorder (BPD I) is a recurrent illness that affects 1% of the US population and constitutes a large economic burden. However, few studies have investigated the cost effectiveness of maintenance treatment options for BPD I.

OBJECTIVE

To determine the cost effectiveness of maintenance treatment with quetiapine fumarate extended-release (XR) tablets in combination with mood stabilizers (lithium or divalproex) in comparison with the following treatments: placebo in combination with lithium or divalproex; no maintenance treatment; lithium monotherapy; lamotrigine monotherapy; olanzapine monotherapy; and aripiprazole monotherapy.

METHODS

The analysis was conducted from the societal and payer perspectives in the US, using a Markov model. The model simulated a cohort of 1000 stabilized BPD I patients and estimated the quarterly risk in three health states: euthymia, mania and depression. Efficacy data were derived from two randomized, double-blind trials comparing quetiapine + lithium/divalproex with placebo + lithium/divalproex for up to 2 years, as well as other published literature. Resource data were extracted from published literature. Drug costs, hospitalizations and physician visits were among the direct costs. Indirect costs included absenteeism, and mortality rates included suicide. Benefits and costs were discounted at 3% and the price reference year was 2009. Endpoints included number of acute mood episodes, hospitalizations due to an acute mood event and costs per QALY. Probabilistic sensitivity analysis (PSA) was conducted to evaluate uncertainty in the model inputs.

RESULTS

Treatment with quetiapine XR + lithium/divalproex was associated with reductions in acute mania (46%), acute depression (41%) and related hospitalizations (44%) compared with placebo + lithium/divalproex, and similar reductions in events were observed relative to lithium monotherapy. In the base-case analysis from the payer perspective, the discounted incremental cost per QALY for quetiapine XR + lithium/divalproex compared with placebo + lithium/divalproex was $US22 959, and compared with lithium monotherapy was $US100 235, while all other comparators were dominated. PSA showed these results to be robust to select assumptions.

CONCLUSIONS

Quetiapine XR + lithium/divalproex may be a cost-effective maintenance treatment option for patients with BPD I.

The cost effectiveness of two new antiepileptic therapies in the absence of direct comparative data: a first approximation

BACKGROUND

A number of new antiepileptic agents have been introduced within a short period of time. Direct comparisons are not available, and information about the balance between costs and effects for these new therapies is lacking.

OBJECTIVE

To introduce a first approximation of the cost effectiveness of the new therapeutic agents (topiramate and lamotrigine) for epilepsy that have been assessed in clinical trials against placebo.

METHODS

Without head to head comparative data no formal methods are available to assess the relative cost effectiveness of two products; therefore, a Bayesian approach was developed. The approach starts with the 'proportionality assumption' saying that the differences in healthcare expenditure (less the direct cost of therapy) are directly proportional to the differences in effectiveness. Given this assumption, a therapy that is x times as expensive as an alternative therapy has an equivalent cost-effectiveness profile if the acquisition cost is x times as high. Moreover, simple formulas can be derived to calculate the probabilities that a therapy is dominant (more effective and less expensive) and that it is weakly dominant (more effective and a better cost-effectiveness profile). The approach is applied to data from published fixed dosage, parallel-design studies comparing both topiramate and lamotrigine with placebo.

RESULTS

Assuming that the 'proportionality assumption' holds for the medical treatment of epilepsy, and disregarding uncertainties, it is estimated that topiramate may be priced more than 2.2 times its current acquisition cost and still be more cost effective than lamotrigine. Taking uncertainties into account, it is estimated that lamotrigine 500 mg/day is dominated by topiramate 200 mg/day with a probability of 0.875 and by topiramate 400 mg/day with a probability of 0.986.

CONCLUSIONS

A simple method can be applied to assess the relative cost effectiveness of two therapies in the absence of direct comparative data. Applying this method to compare topiramate and lamotrigine leads to a strong preference for topiramate. However, to be able to draw this conclusion, some heroic assumptions need to be made. As such the method as developed here only reflects a first approximation. It needs to be used with care and is not intended to replace good comparative research.

Cost-effectiveness of add-on lamotrigine therapy in clinical practice

OBJECTIVE

This retrospective study addresses the cost-effectiveness of add-on therapy with lamotrigine in clinical practice.

METHODS

Two years' observational data of 165 patients were used. Seizure frequency, adverse effects and direct medical costs were recorded for the year before and the year after the start of lamotrigine add-on therapy. Therapy effectiveness was measured by: (1) reduction in seizure frequency and (2) retention time. The incremental cost-effectiveness ratio expressed the direct medical cost per patient treated effectively with lamotrigine.

RESULTS

The cost of medication was 492 (95% CI: 399-583) higher after the start of lamotrigine therapy. The extra cost of lamotrigine therapy (622) was partly offset by a reduction of the cost of co-medication (-130; 95% CI: -210 to -50). Overall, the total medical cost was 453 higher in the first year of lamotrigine therapy than in the year before the start of lamotrigine. Lamotrigine was effective in 47% of all the patients, making the resultant incremental cost-effectiveness ratio 954 per year.

DISCUSSION

Add-on therapy of lamotrigine for patients with uncontrolled epilepsy offers improved health outcomes. Lamotrigine therapy is associated with increased cost (453) and an annual incremental cost-effectiveness ratio of 954. These data, together with utility data published in the literature, support the notion that lamotrigine should be considered as an add-on therapy in for patients with refractory epilepsy.

The impact on health outcomes and healthcare utilisation of switching to generic medicines consequent to reference pricing: the case of lamotrigine in New Zealand

BACKGROUND

Many countries have implemented generic reference pricing and substitution as methods of containing pharmaceutical expenditure. However, resistance to switching between medicines is apparent, especially in the case of anti-epileptic medicines.

OBJECTIVES

This study sought to exploit a nation-wide policy intervention on generic reference pricing in New Zealand to evaluate the health outcomes of patients switching from originator to generic lamotrigine, an anti-epileptic medicine.

METHODS

A retrospective study using the national health collections and prescription records was conducted comparing patients who switched from originator brand to generic lamotrigine with patients who remained on the originator brand. Primary outcome measures included switch behaviour, changes in utilisation of healthcare services at emergency departments, hospitalisations and use of specialist services, and mortality.

RESULTS

Approximately one-quarter of all patients using the originator brand of lamotrigine switched to generic lamotrigine, half of whom made the switch within 60 days of the policy implementation. Multiple switches (three or more) between generic and brand products were evident for around 10% of switchers. Switch-back rates of 3% were apparent within 30 days post-switch. No difference in heath outcome measures was associated with switching from originator lamotrigine to a generic equivalent and hence no increased costs could be found for switchers.

CONCLUSIONS

Switching from brand to generic lamotrigine is largely devoid of adverse health outcomes; however, creating an incentive to ensure a greater proportion of patients switch to generic lamotrigine is required to achieve maximal financial savings from a policy of generic reference pricing.

A cost-effectiveness decision model for antiepileptic drug treatment in newly diagnosed epilepsy patients

OBJECTIVE

To establish cost-effectiveness of antiepileptic drug (AED) treatment strategies of newly diagnosed patients with epilepsy.

METHODS

A decision analysis was carried out comparing effectiveness and treatment cost of six treatment strategies comprising carbamazepine (CBZ), lamotrigine (LTG), and valproate (VPA) as first-line and second-line drugs. Three outcome groups were defined: complete success, partial success, and failure. Data on seizure control and failure due to adverse effects were derived from the literature. Data on resource use and costs were collected for each outcome group by means of a patient survey.

RESULTS

Cost data were obtained from 71 patients. Cost increased from complete success to failure outcome groups. The probability of obtaining complete success varied from 64% (VPA-CBZ strategy) to 74% (LTG-VPA strategy). The strategy LTG-VPA was more effective than the least expensive strategy CBZ-VPA, but at higher costs per additional effectively treated patient. Probabilistic sensitivity analysis confirmed these findings to be robust. Subsequent analysis showed that changing inclusion criteria used in the selection of the studies from the literature had a major effect on cost-effectiveness ratios of the various strategies. The probability that LTG first-line therapy is the most cost-effective option remains small, even defining a high cost-effectiveness threshold. Nevertheless, LTG second-line strategies can be cost-effective depending on the willingness to pay for patient improvement.

CONCLUSIONS

Only a few studies satisfied our inclusion criteria for employment in our decision model. Our model supports the use of conventional AEDs as first-line options for patients with newly diagnosed epilepsy. LTG second-line therapy is likely to be the most cost-effective option in case society is willing to pay more than Euro 6000 for an additional successfully treated patient. This study also illustrates that, with the data presently available, the outcome of decision analysis for AED treatment choice depends on the inclusion criteria used to select trials. Prospective real-life studies are needed in which first- and second-line treatment strategies are compared with respect to both effectiveness and costs.

Volume and market share of anti-epileptic drugs in the Netherlands: impact of new drugs

OBJECTIVE

In the past decade, several new anti-epileptic drugs (AEDs) were introduced in The Netherlands. These new drugs, one of which is lamotrigine, are 6 to 10 times more expensive than conventional anti-convulsants. In 1997, the high cost of lamotrigine, together with a lack of clinical data supporting its superiority over conventional drugs, prompted the Dutch Health Insurance Board to release a guideline in which the use of lamotrigine was restricted to difficult-to-treat patients. Other new drugs that were marketed after 1997 also became subject to this guideline. The utilisation of new AEDs and the cost consequences are the subject of this paper.

METHODS

Data from extramurally prescribed AEDs was obtained from the Dutch Drug Information Project, which is a database containing prescriptions for about 5.5 million inhabitants of the Netherlands. This data was used to study the impact of new AEDs on volume and market share of AEDs in the period from 1995 to 2001 in The Netherlands.

RESULTS

Between 1995 and 2001, the total volume of AEDs increased by 130%, 60% of which consisted of new AEDs. Gabapentin, lamotrigine and oxcarbazepine were the most frequently prescribed new compounds. The volume share of new AEDs increased from 5% in 1995 to 18% in 2001. The market share amounted to 21.5 million euros in 1995 and rose to 47 million euros in 2001; 80% of this increase was due to the introduction of new AEDs.

DISCUSSION

Although in 2001 the volume share of new AEDs was still modest, their introduction has led to a strong increase in the cost. New data is emerging on the effectiveness and cost-benefit sum of the new AEDs; this may change the place in therapy of these drugs. Because of their strong potential to force up cost, the positioning of new AEDs requires further attention.

Incremental cost-effectiveness of various monthly doses of vardenafil

OBJECTIVE

To compare the cost-effectiveness of four, six, and eight doses per month of vardenafil in the context of pharmacy benefit decision making.

METHODS

A Markov model was used to estimate the incremental cost-effectiveness of zero, four, six, or eight doses of vardenafil per month in hypothetical cohorts of 60-year-old male veterans with erectile dysfunction. Efficacy values for vardenafil were obtained from the literature, and vardenafil costs were obtained from Veterans Affairs pharmacy data. The analysis was conducted from a third-party payer perspective with a lifetime horizon, and the effect of parameter uncertainty was explored in one-way and probabilistic sensitivity analyses.

RESULTS

In the base case analysis, the cost per quality-adjusted life-year gained for four doses of vardenafil per month compared with no therapy was $576. Six doses per month compared with four cost $2585/quality-adjusted life-year gained, and eight doses per month compared with six cost $5169/quality-adjusted life-year gained. In one-way sensitivity analyses of six doses per month compared with four, variation of two parameters caused the incremental cost-effectiveness ratio to cross a willingness-to-pay threshold of $20,000: when the increased utility associated with giving two additional doses/month was less than 0.001 (baseline 0.01) and when the cost per dose increased to $15.00 (baseline $1.69).

CONCLUSION

Although four doses per month of vardenafil was the most cost-effective strategy, the use of six or eight doses per month also compares favorably with other accepted medical treatments. The results were stable across a range of inputs and help to support the current Veterans Affairs policy on the number of vardenafil doses provided per month for erectile dysfunction.