Cost-effectiveness analysis in Parkinson's disease: determining the value of interventions

Cholinesterase inhibitor to prevent falls in Parkinson's disease (CHIEF-PD) trial: a phase 3 randomised, double-blind placebo-controlled trial of rivastigmine to prevent falls in Parkinson's disease

BACKGROUND

Falls are a common complication of Parkinson's disease. There is a need for new therapeutic options to target this debilitating aspect of the disease. Cholinergic deficit has been shown to contribute to both gait and cognitive dysfunction seen in the condition. Potential benefits of using cholinesterase inhibitors were shown during a single centre phase 2 trial. The aim of this trial is to evaluate the effectiveness of a cholinesterase inhibitor on fall rate in people with idiopathic Parkinson's disease.

METHODS

This is a multi-centre, double-blind, randomised placebo-controlled trial in 600 people with idiopathic Parkinson's disease (Hoehn and Yahr stages 1 to 4) with a history of a fall in the past year. Participants will be randomised to two groups, receiving either transdermal rivastigmine or identical placebo for 12 months. The primary outcome is the fall rate over 12 months follow-up. Secondary outcome measures, collected at baseline and 12 months either face-to-face or via remote video/telephone assessments, include gait and balance measures, neuropsychiatric indices, Parkinson's motor and non-motor symptoms, quality of life and cost-effectiveness.

DISCUSSION

This trial will establish whether cholinesterase inhibitor therapy is effective in preventing falls in Parkinson's disease. If cost-effective, it will alter current management guidelines by offering a new therapeutic option in this high-risk population.

TRIAL REGISTRATION

REC reference: 19/SW/0043. EudraCT: 2018-003219-23.

ISCRTN

41639809 (registered 16/04/2019). ClinicalTrials.gov Identifier: NCT04226248 PROTOCOL AT TIME OF PUBLICATION: Version 7.0, 20th January 2021.

A Two-Stage Tremor Detection Algorithm for Wearable Inertial Sensors During Normal Daily Activities

Continuous monitoring of tremor with wearable wrist sensors during normal daily activities is more difficult than in a clinical setting when subjects perform prescribed activities because some normal daily activities resemble tremor, many normal movements contain frequency content that overlaps with the tremor frequency, and the tremor amplitude has a large dynamic range during normal daily activities. We describe a novel two-stage algorithm that offers improvement at discriminating tremor from other activities. Some of this improvement is attained by using prior domain knowledge that tremor occurs over a narrow range of frequencies for an individual, but the mean tremor frequency may vary significantly between individuals in a study population. We validated the algorithm in continuous recordings from people with Parkinson's disease and matched control subjects. The algorithm has good face validity, a low rate of false positives on recordings from control subjects (<; 1.1%), and good correspondence with the constancy of rest tremor as measured by this question on the MDS-UPDRS (ρ = 0.54).

Evaluation of exercise-induced modulation of glial activation and dopaminergic damage in a rat model of Parkinson's disease using [11C]PBR28 and [18F]FDOPA PET

Evidence suggests that exercise can modulate neuroinflammation and neuronal damage. We evaluated if such effects of exercise can be detected with positron emission tomography (PET) in a rat model of Parkinson's disease (PD). Rats were unilaterally injected in the striatum with 6-hydroxydopamine (PD rats) or saline (controls) and either remained sedentary (SED) or were forced to exercise three times per week for 40 min (EX). Motor and cognitive functions were evaluated by the open field, novel object recognition, and cylinder tests. At baseline, day 10 and 30, glial activation and dopamine synthesis were assessed by [¹¹C]PBR28 and [¹⁸F]FDOPA PET, respectively. PET data were confirmed by immunohistochemical analysis of microglial (Iba-1) / astrocyte (GFAP) activation and tyrosine hydroxylase (TH). [¹¹C]PBR28 PET showed increased glial activation in striatum and hippocampus of PD rats at day 10, which had resolved at day 30. Exercise completely suppressed glial activation. Imaging results correlated well with post-mortem Iba-1 staining, but not with GFAP staining. [¹⁸F]FDOPA PET, TH staining and behavioral tests indicate that 6-OHDA caused damage to dopaminergic neurons, which was partially prevented by exercise. These results show that exercise can modulate toxin-induced glial activation and neuronal damage, which can be monitored noninvasively by PET.

Economic Evaluation of Interventions in Parkinson's Disease: A Systematic Literature Review

BACKGROUND

Parkinson's disease (PD) management comprises of drug treatments, surgery, and physical activity/occupational therapies to relieve PD's symptoms. The aim of this study is twofold; first, to appraise recent economic evaluation studies on PD management in order to update the existing knowledge; and second, to facilitate decision making on PD management by assessing the cost-effectiveness of all types of PD interventions.

METHODS

A systematic search for studies published between 2010 and 2018 was conducted. The inclusion and exclusion of the articles were based on criteria relevant to population, intervention, comparison, outcomes, and study design (PICO). The reporting quality of the articles was assessed according to Consolidated Health Economic Evaluation Reporting Standards.

RESULTS

Twenty-eight articles were included, 10 of which were evaluations of drug treatments, 10 deep brain stimulation (DBS), and eight physical/occupational therapies. Among early-stage treatments, Ti Ji dominated all physical activity interventions; however, its cost-effectiveness should be further explored in relation to its duration, intensity, and frequency. Multidisciplinary interventions of joint medical and nonmedical therapies provided slightly better health outcomes for the same costs. In advanced PD patients, adjunct drug treatments could become more cost-effective if introduced during early PD and, although DBS was more cost-effective than adjunct drug therapies, the results were time-bound.

CONCLUSIONS

Conditionally, certain PD interventions are cost-effective. However, PD progression differs in each patient; thus, the cost-effectiveness of individually tailored combinations of interventions that could provide more time in less severe disease states and improve patients' and caregivers' quality of life, should be further explored.

Economic Analysis of Deep Brain Stimulation in Parkinson Disease: Systematic Review of the Literature

BACKGROUND

Parkinson disease (PD) is a chronic multifaceted neurodegenerative disorder of adult onset that affects quality of life and places a burden on patients, caregivers, and society. In early disease, dopaminergic therapy improves motor symptoms, but as the disease progresses, symptoms tend to increase in frequency and severity, even with best medical treatment (BMT). Deep brain stimulation (DBS) becomes an option for certain patients, but cost becomes an important issue.

OBJECTIVE

We performed a systematic review of the literature of economic studies of the use of DBS in patients with PD, including costs studies or economic evaluations expressed as cost per improvement in quality life, decrease in dose of pharmacological treatments, and the decrease of caregiver burden.

METHODS

We reviewed the following databases: Medline/PubMed, Embase, Cochrane Database of Systematic Reviews, LILACS, Cochrane Central Register of Controlled Trials, WHO International Clinical Trials Registry Platform ICTRP portal and ClinicalTrials.gov from 1980 to 2015. Costs have been converted or adjusted to 2016 US dollars (US$).

RESULTS

Nine studies were identified. The average cost of DBS for a patient with PD in 5 years is US$186,244. The quality-adjusted life year was higher in DBS compared with BMT after at least 2 years of treatment, with an average incremental cost utility ratio of US$41,932 per additional quality-adjusted life year gained. Costs in the first year are higher with DBS because of direct costs related to the surgical procedure, the device, and the more frequent controls. Studies show better results with a longer time horizon (up to 5 years).

CONCLUSION

DBS is a cost-effective intervention for patients with advanced PD, but it has a high initial cost compared with BMT. However, DBS reduces pharmacologic treatment costs and should also reduce direct, indirect, and social costs of PD on the long term.

Drug and treatment costs in Parkinson's disease patients in Sweden

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disease expected to cause great costs. The aim of this study was to calculate drug and treatment costs in patients with PD in Sweden.

METHOD

All healthcare contacts of patients with PD in Stockholm County, Sweden, were extracted from registers together with information on reimbursements from the authorities to the caregivers. PD-related costs were calculated together with non-PD-related costs. Cost per patient was calculated and extrapolated to the whole Swedish population, taking population demographics into consideration. In addition, nationwide PD drug sales statistics were included.

RESULTS

The PD prevalence of Stockholm County was estimated to 196 per 100,000 inhabitants, resulting in an estimated total of about 22,000 patients with PD in Sweden. The cost per patient was estimated to SEK 76,000 of which drug costs accounted for SEK 15,880. The annual direct costs in patients with PD in Sweden were SEK 1.7 billion in 2009.

CONCLUSION

Our study estimates high direct costs in patients with PD in Sweden, SEK 1.7 billion, 52% for inpatient care, 27% for outpatient care and 21% for drugs. With an ageing population and the medical progress, the financial burden on society will most probably increase in the future. This study might initiate and provide information for discussions about future cost allocations and healthcare priorities.

Pharmacotherapy in the management of early Parkinson's disease: cost-effectiveness and patient acceptability

In the absence of a cure, the primary goals in managing Parkinson's disease (PD) are to preserve functionality and health-related quality of life (HRQoL). Current therapeutic strategies for PD include symptomatic treatment and are primarily focused on replacing dopamine in the brain. Dopamine agonists can be used as an alternative initial levodopa therapy, to delay the onset of motor complications, but at the expense of more dopaminergic adverse effects; poorer control of motor symptoms; and increased cost. In PD, treatment effects and costs accumulate over time; hence the choice of time horizon in cost-effectiveness analysis can be particularly important. Pharmaceutical expenditures have grown rapidly in recent decades and now total nearly 10% of all health care costs. The main approach to treat PD at the present time is to advance knowledge of the efficacy, to reduce long-term complications associated with treatment, and to improve patient HRQoL and society burden. The implementation of cost-effectiveness studies, including the societal perspective, should be considered as an outcome of new therapy strategies, which would be helpful to health care decision makers.

How should we treat a patient with early Parkinson's disease?

Parkinson's disease (PD) is characterised by the progressive degeneration of dopaminergic nigro-striatal neurons and severe striatal dopaminergic deficiency, leading to bradykinesia. Levodopa was the first drug used for PD treatment and is still considered the most useful weapon for the control of PD symptoms. However, levodopa treatment induces motor complications, which is considered as a major problem as the disease progresses. Dopamine agonists, catechol-O-methyltransferase inhibitors and monoamine oxidase B inhibitors are some more recently developed drug categories which are expected to have a more favourable effect on motor complications. The choice of the best initial treatment in PD remains a controversial matter. Early therapeutic decisions in PD should balance the need for efficient short-term symptom control against long-term complication profile. The individualisation of the treatment seems to be the key for the best approach of early PD patients.

Cost effectiveness of pharmacotherapies in early Parkinson's disease

Parkinson's disease is one of the most common chronic neurodegenerative diseases. The progression of disease and the psychosocial consequences exert a major impact on patients' health-related quality of life. Although levodopa provides the best symptomatic benefit with the fewest short-term adverse effects, long-term treatment results in motor complications that are associated with both higher costs and considerable increase in patients' discomfort. The introduction of dopamine agonists early in the treatment of Parkinson's disease leads to a delay of these motor complications, but the treatment is associated with higher costs.In this review we evaluate available cost-effectiveness analyses of the dopamine agonists pramipexole, pergolide, bromocriptine, ropinirole, cabergoline and levodopa in the treatment of early Parkinson's disease. Considerable methodological differences in the identified studies complicate a comparison and impede clear evidence as to which dopamine agonist treatment is the most cost effective in early Parkinson's disease. Novel head-to-head comparisons considering the actual treatment guidelines are necessary to identify the most cost-effective alternative in treating de novo Parkinson's disease patients.

Predicting the cost of Parkinson's disease

The degenerative nature of Parkinson's disease (PD) suggests that it will lead to high levels of resource use. This study measures service use and costs for a representative community sample of PD patients and identifies cost predictors. Patients were identified from general practices and were interviewed twice, separated by a 12-month interval. Demographic and clinical data on patients were collected and 6-month costs were calculated. Regression analysis was used to identify significant baseline predictors of follow-up costs. The annual service costs (baseline and follow-up combined) were 13,804 pounds per person. Formal service costs accounted for 20% of this figure with informal care from families/friends accounting for 80%. The regression model explained 42% of total follow-up costs and significant predictors included gender (with men having higher costs), disability, and depression.

ICD-9 CM code 333.1 as an identifier of patients with essential tremor: a study of the positive predictive value of this code

BACKGROUND/AIMS

Health outcomes research often uses administrative databases. Patients with the diseases of interest are identified using International Classification of Diseases (ICD-9 CM) codes. The utility of the code for essential tremor (ET), 333.1, remains untested. We determined the positive predictive value (PPV) of the code 333.1.

METHODS

Patients with the ICD-9 CM code 333.1 were identified from billing records at the Neurological Institute of New York. Their medical records were reviewed to determine whether they met Consensus Criteria for ET.

RESULTS

Of 964 patients who carried the code 333.1, only 472 met diagnostic criteria for ET (i.e. PPV = 49.0%). The additional use of ICD 9-CM codes for parkinsonism and dystonia (as exclusionary criteria) only marginally improved this value (57.8%). Common diagnoses among the false positives were Parkinson's disease, dystonia, enhanced physiological tremor, drug-induced tremor, orthostatic tremor, and psychogenic tremor. Patients seen by general neurologists (vs. movement disorder specialists) were half as likely to meet diagnostic criteria for ET (34.6 vs. 51.9%, OR 0.50, 95% CI 0.23-0.70, p < 0.001).

CONCLUSION

The code 333.1 performed poorly when attempting to identify ET cases. Given the very high prevalence of ET, a unique diagnostic code would seem to be in order.

Economic burden associated with Parkinson's disease on elderly Medicare beneficiaries

We evaluated medical utilization and economic burden of self-reported Parkinson's disease (PD) on patients and society. Using the 1992-2000 Medicare Current Beneficiary Survey, we compared health care utilization and expenditures (in 2002 U.S. dollars) of Medicare subscribers with and without PD, adjusting for sociodemographic characteristics and comorbidities. PD patients used significantly more health care services of all categories and paid significantly more out of pocket for their medical services than other elderly (mean+/- SE, 5,532 dollars+/- 329 dollars vs. 2,187 dollars+/- 38 dollars; P<0.001). After adjusting for other factors, PD patients had higher annual health care expenses than beneficiaries without PD (18,528 dollars vs. 10,818 dollars; P<0.001). PD patients were more likely to use medical care (OR=3.77; 95% CI=1.44-9.88), in particular for long-term care (OR=3.80; 95% CI=3.02-4.79) and home health care (OR=2.08; 95% CI=1.76-2.46). PD is associated with a significant economic burden to patients and society. Although more research is needed to understand the relationship between PD and medical expenditures and utilization, these findings have important implications for health care providers and payers that serve PD populations.

A Review of the Health-Related Quality of Life and Economic Impact of Parkinson??s Disease

Parkinson's disease (PD) is a chronic, neurodegenerative disease that places a substantial burden on patients, their families and carers, as well as on society as a whole. PD can severely affect the health-related quality of life (HR-QOL) of both patients and their carers and, as the disease progresses, HR-QOL deteriorates. This review aims to critically evaluate the literature on a number of important aspects that influence HR-QOL in relation to PD. Factors associated with a negative impact and ways to improve HR-QOL are highlighted, and tools for HR-QOL assessment reviewed. The economic impact of PD and related cost-effectiveness studies are also reviewed. Over the course of the disease, patients with PD experience changes in their HR-QOL that are affected by factors such as depression, motor complications, education and surgery. However, a lack of uniformity in the choice of HR-QOL tools used in studies makes comparison of results difficult. Research on motor fluctuations and dyskinesias has shown conflicting results, whereas it is clear from the available data that depression needs to be more clearly recognised and treated. Inequality in the numbers of men and women receiving surgery still needs to be addressed and, again, in this area there is a lack of uniformity with respect to assessment for surgery. Education programmes have been shown to be successful in improving HR-QOL, although more research is needed about how to introduce such programmes to all PD patients. In particular, there has been little detailed research into young-onset PD and juvenile patients to assess the true impact of the disease on their HR-QOL. The literature has also shown that PD can affect the HR-QOL of the carer, which may have a 'knock-on' effect for the patient. The HR-QOL of carers needs more attention because these individuals can significantly reduce the burden that would otherwise fall on the health services in terms of cost and care. Research shows that the economic costs of PD are high, particularly for patients in advanced stages of the disease and those with motor complications. Although carer burden is a major source of costs, this is not factored into cost-effectiveness analyses. Furthermore, because too few studies use quality-adjusted life years as their health outcome, particularly in studies of the costs of surgery, comparison of costs of treatments is difficult. The review highlights the need for HR-QOL tools such as the EuroQol-5D to be used together with disease-specific tools to provide the most comprehensive picture of the costs and impact of PD.A recent upsurge in published literature on PD resulting from increased interest in HR-QOL issues has led to an at times overwhelming amount of new information. The present review assembles the most important points relating to HR-QOL in PD raised in the literature, adds value to previously covered issues, and examines areas of HR-QOL in PD that have not previously been reviewed, such as education, carer burden and surgery, highlighting where more research is warranted.

Functional improvement after subthalamic stimulation in Parkinson's disease: a non-equivalent controlled study with 12-24 month follow up

OBJECTIVE

This study aimed to assess the effectiveness of chronic bilateral STN-S in improving the functional status of PD patients compared with patients treated with drugs alone.

METHODS

Controlled study of disability index changes over 12 and 24 month chronic STN stimulation. Of 39 patients with advanced PD meeting CAPSIT criteria for STN-S, 23 underwent surgery; 16 patients decided against surgery and continued on drug schedule adjustments. Functional status was measured using the Activities of Daily Living section of the Unified Parkinson's Disease Rating Scale (UPDRS-ADL), Brown's Disability Scale, and Functional Independence Measure. UPDRS motor score and subscores for selected items, levodopa equivalent daily dose, and Beck Depression Inventory scores were also monitored.

RESULTS

T12 follow up data were available for all 39 patients and T24 data for 13 STN-S and 8 control subjects. Compared with controls, STN-S patients experienced significant or highly significant improvements in all independence measures at both 12 and 24 months (time x treatment effect T12: F = 19.5, p = 0.00008; T24: F = 6.2, p = 0.005). Forward stepwise regression for independent predictors of the yearly rate of UPDRS-ADL score modification in the entire sample showed that treatment was the only factor significantly associated with functional status change (beta coefficient -0.54, t value -2.5, p = 0.02), whereas other variables-UPDRS motor score, BDI, and age at disease onset and enrolment-were not in the equation.

CONCLUSION

STN-S is an effective therapeutic option in advanced PD. It induced a consistent improvement of functional abilities over two years to an extent that was not achieved with drug therapy alone.

Systematic assessment of decision models in Parkinson's disease

OBJECTIVE

To give an insight into the structural and methodological approaches used in published decision-analytic models evaluating interventions in Parkinson's disease (PD) and to derive recommendations for future comprehensive PD decision models.

METHODS

A systematic literature review was performed to identify studies that evaluated PD interventions using mathematical decision models. Using a standardized assessment form, information on the study design, methodological framework, and data sources was extracted from each publication and systematically reported. Strengths and limitations were assessed.

RESULTS

We identified eight studies that used mathematical models to evaluate different pharmaceutical (n=7) and surgical (n=1) treatment options in PD. All models included economic evaluations. Modeling approaches comprised mathematical equations, decision trees, and Markov models with a time horizon ranging from 5 years to lifetime. All based progression on the evolution of clinical surrogate endpoints. Treatment effects were either modeled via reduction of symptomatic progression and/or initial symptomatic improvement or via reduction of adverse effect rates. No model is currently available that encompasses both the underlying biologic disease progression and the spectrum of all relevant complications and also links them to patient preferences and economic outcomes.

CONCLUSIONS

Models have been successfully applied to evaluate PD treatments. However, currently available models have substantial limitations. We recommend that a comprehensive, generic, and flexible decision model for PD that can be applied to different treatment strategies should consider a large spectrum of clinically relevant outcomes and complications of the disease during a sufficiently long time horizon, include PD-specific mortality, systematically evaluate uncertainty including heterogeneity effects, and should be validated by independent data or other models. Approaches to model treatment effects included reduction of symptomatic progression, initial symptomatic improvement, or reduction of adverse effects. We believe that structural bias could be avoided if underlying disease progression and treatment effects on symptoms are modeled separately.

Neuroprotection and pharmacotherapy for motor symptoms in Parkinson's disease

Parkinson's disease leads to major disability that impairs the quality of life of patients and leads to increased health-care costs. While there is no proven neuroprotective treatment, more basic-science research and clinical trials are needed to identify drugs that slow or halt the progression of the disorder. The mainstay of symptomatic treatment is levodopa. With long-term use, levodopa causes motor complications including involuntary movements and response fluctuations. These have lead to more cautious prescribing of levodopa. Dopamine agonists can be used as an alternative initial therapy to delay the onset of motor complications but at the expense of more dopaminergic adverse events, poorer control of motor symptoms, and increased cost. Once motor complications have developed, adjuvant therapy with dopamine agonists or entacapone can reduce off time and levodopa dose. Severe fluctuations that are not controlled by oral combination therapy can be controlled with subcutaneous apomorphine injections or infusions.

The economic evaluation of pharmacotherapies for Parkinson's disease

As well as the significant clinical effects of Parkinson's disease (PD), the disease places a high economic burden on society. Given the scarcity of health care resources, it is becoming increasingly necessary to demonstrate that new therapies for PD provide value for money in comparison with other potential interventions. This paper outlines the basic techniques of cost-effectiveness analysis and its application to PD. These techniques are illustrated by a recent economic evaluation of entacapone for use in Canada.

Impact of social functioning and vitality on preference for life in patients with Parkinson's disease

The determinants of preference for life in patients with Parkinson's disease are not well known. We assessed the effect of functional status on the preference for life as measured by the time trade-off method with a 10-year life span. Our survey was based on a random sample of 1,200 patients from the Japanese Association of Patients with Parkinson's Disease. Patients' demographics, clinical information, and functional status as measured by the MOS Short Form 36 were considered independent variables. The response rate was 63.5%. Linear regression showed that men had a significantly stronger preference for current health than women (by 10.4 months on a scale of 10 years). Patients with higher physical functioning, social functioning, and vitality had significantly higher preferences for life (each 10-point improvement in physical or social functioning led to a 1.5-month increment in preference for current health; a 10-point improvement in vitality led to a 3-month increment). Longer duration of disease and advanced Hoehn and Yahr stage were significantly associated with a lower preference for current health (by 0.5 months/year of disease and by 2.6 months/stage). Interventions that target social functioning and vitality may be beneficial to preference for life.

Resource use and costs in a Swedish cohort of patients with Parkinson's disease

We estimated resource use and costs in patients with Parkinson's disease (PD), thereby providing baseline data for future economic evaluations of therapeutic interventions. Data were collected from medical records of a South Swedish cohort of 127 PD patients during 1 year (1996) and a mailed questionnaire inquiring about cost-related consequences and resource use in 1996 and in 2000. Annual costs were calculated based on prevalence and expressed in SEK (monetary value of the year 2000). Direct health care costs averaged approximately SEK 29,000 ( approximately USD 2,900; EUR 3,200) per patient per year, of which drugs were the most costly component. Nonmedical direct costs were higher than direct health care costs, averaging approximately SEK 43,000 ( approximately USD 4,300; EUR 4,800) per patient per year, and costs due to lost production were approximately SEK 52,000 ( approximately USD 5,200; EUR 5,800) per patient per year. The mean total annual cost for PD in our sample approximated SEK 124,000 ( approximately USD 12,400; EUR 13,800) per patient. These findings are roughly within the same range as estimates from other countries and show that PD causes a considerable societal burden. In addition to other outcomes, evaluations of the economic implications of new therapeutic interventions are highly warranted. In this perspective, the present study provides valuable baseline data.

Drug treatment of non-motor symptoms in Parkinson's disease

Non-motor symptoms may considerably reduce parkinsonian quality of life, particularly in advanced stages of the disease. Autonomic features, such as seborrhoea, hyperhidrosis, orthostatic hypotension, excessive salivation, bladder dysfunction and GI disturbances, and neuropsychiatric symptoms, such as depression, sleep disorders, psychosis and dementia, appear in the course of Parkinson's disease. Pharmacotherapy of these non-motor symptoms complicates long-term antiparkinsonian combination drug therapy due to possible drug interactions, side effects and changes in metabolism. Moreover, antiparkinsonian compounds themselves contribute to the onset of these non-motor symptoms to a considerable extent. This complicates differentiation between the disease process itself and drug-related effects, thus influencing therapeutic options, which are often limited because of comorbidity and polypharmacy. Therefore, standardised recommendations are questionable, since drug tolerability and response differ between patients. Nevertheless, this review tries to provide a survey of possible therapeutic options for the treatment of the symptoms of Parkinson's disease other the dopamine-sensitive motor features.

Current evidence for neuroprotective effects of nicotine and caffeine against Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting 1 to 3% of individuals over the age of 65 years. While effective therapy exists for treating the bradykinesia, rigidity and tremor associated with the disease, the cause is unknown. There is no treatment available to prevent or slow the progressive neuronal loss in the substantia nigra and associated decreased levels of dopamine in the striatum that underlie the cardinal features of the disease. Both retrospective and prospective epidemiological studies have consistently demonstrated an inverse association between cigarette smoking and PD, leading to theories that smoking in general and nicotine in particular might be neuroprotective. Nicotine has been shown in animals to stimulate the release of dopamine in the striatum, and to preserve nigral neurons and striatal dopamine levels in laboratory animals with lesioned nigrostriatal pathways. Coffee and caffeine consumption have also been shown in epidemiological studies to be inversely related to PD risk. Caffeine is an adenosine A(2A) receptor antagonist that enhances locomotor activity in animal models of parkinsonism. Theophylline, a related compound that has A(2A) receptor blocking properties, has been shown in one small trial to improve motor function in patients with PD. Recently, potent and highly selective A(2A) receptor antagonists have been developed that have demonstrated improvement in motor function in animal models of parkinsonism. Exciting findings are emerging that demonstrate attenuation of dopaminergic neurotoxicity with caffeine and other adenosine receptor antagonists in mice given the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), suggesting that these compounds may be neuroprotective. Evidence for the neuroprotective potential of nicotine and caffeine is compelling, but further work is needed before testing these and related compounds in clinical trials for both individuals at high risk of developing PD and those with early, untreated disease.

Cost-effectiveness analysis of dopamine agonists in the treatment of Parkinson's disease in Japan

BACKGROUND

Dopamine agonists such as bromocriptine or pergolide are often used in Japan to treat Parkinson's disease. Dopamine agonists are relatively expensive drugs; economic evaluations are required.

OBJECTIVE

To evaluate the cost effectiveness of dopamine agonists for the treatment of Parkinson's disease in Japan.

DESIGN AND SETTING

We used a Markov model to simulate the course of Parkinson's disease and to compare the cost effectiveness of dopamine agonists added to levodopa with that of levodopa alone in Japan. The model assumed that 60-year-old men with Parkinson's disease in Hoehn-Yahr (HY) stages 2 to 5 using levodopa were administered dopamine agonists or continued on levodopa alone. The incremental cost effectiveness of dopamine agonists used for 10 years was then estimated.

STUDY PERSPECTIVE

Societal.

MAIN OUTCOME MEASURES AND RESULTS

In the patients in HY stage 2, the incremental cost effectiveness of dopamine agonists was 18,610,000 to 19,320,000 yen per quality-adjusted life-year (QALY) [$US 172,300 to $US 178,900/QALY; 1998 values] . In patients in HY stage 3 or higher, the use of dopamine agonists was dominant over levodopa alone mainly due to reduced cost for care. In sensitivity analyses, costs and effectiveness of dopamine agonists significantly influenced the results. The use of a generic formulation of bromocriptine was dominant over levodopa alone even in the patients with HY stage 2 disease.

CONCLUSIONS

Dopamine agonists appear to be cost effective in advanced Parkinson's disease, although their use is sensitive to the costs and effectiveness of dopamine agonists. If factors discouraging the prescription of generic drugs in Japan were removed, the treatment of Parkinson's disease would become more cost effective.

Gamma knife thalamotomy for treatment of tremor: long-term results

Object. The purpose of this study was to investigate the long-term effects of gamma knife thalamotomy for treatment of disabling tremor.

Methods. One hundred fifty-eight patients underwent magnetic resonance imaging—guided radiosurgical nucleus ventralis intermedius (VIM) thalamotomy for the treatment of parkinsonian tremor (102 patients), essential tremor (52 patients), or tremor due to stroke, encephalitis, or cerebral trauma (four patients). Preoperative and postoperative blinded assessments were performed by a team of independent examiners skilled in the evolution of movement disorders. A single isocenter exposure with the 4-mm collimator helmet of the Leksell gamma knife unit was used to make the lesions.

In patients with Parkinson's disease 88.3% became fully or nearly tremor free, with a mean follow up of 52.5 months. Statistically significant improvements were seen in Unified Parkinson's Disease Rating Scale tremor scores and rigidity scores, and these improvements were maintained in 74 patients followed 4 years or longer.

In patients with essential tremor, 92.1% were fully or nearly tremor free postoperatively, but only 88.2% remained tremor free by 4 years or more post-GKS. Statistically significant improvements were seen in the Clinical Rating Scale for tremor in essential tremor patients and these improvements were well maintained in the 17 patients, followed 4 years or longer. Only 50% of patients with tremor of other origins improved significantly.

One patient sustained a transient complication and two patients sustained mild permanent side effects from the treatments.

Conclusions. Gamma knife VIM thalamotomy provides relief from tremor equivalent to that provided by radiofrequency thalamotomy or deep brain stimulation, but it is safer than either of these alternatives. Long-term follow up indicates that relief of tremor is well maintained. No long-term radiation-induced complications have been observed.