Parkinson’s disease (PD) is the second most common neurodegenerative disorder worldwide, the first being Alzheimer’s disease. In industrialised countries, PD has an estimated overall prevalence of 0.3 % and an estimated 1 % prevalence in the population of individuals over 60 years of age. PD disease manifests itself through neuromotor symptoms such as tremor, bradykinesia, rigidity and postural instability, as well as cognitive and neuropsychiatric changes, with PD patients presenting an increased risk of developing dementia or depression, amongst other disturbances of the thought, mood, speech and behaviour.1
There are several pharmaceuticals available for the management of PD, but none that reaches the cure. With no cure yet possible, PD progresses chronically, affecting an increasing number of patients, imposing a heavy burden on these patients, their families, caregivers and on health and social support systems.2,3
Economic Evaluation in Healthcare
One of the many areas in which economic evaluations are performed is in the field of health comprehending healthcare provision, products and systems. In economics, as a premise, resources are limited and the needs upon their use are potentially unlimited. Thus, economic evaluations attempt to combine those conflicting realities by proposing guidelines for allocation of existing resources in the most rational way in order to meet the greatest number of needs while maximising the health of the population.
Any contemporary healthcare system has to respond to the growing needs of the population covered, while having limited resources available to address those needs. To this problem adds the financial stress imposed by continuous healthcare innovation: with new drugs and new health technologies being created regularly, and increasingly faster. Therefore, it is of utmost importance and interest to payers of healthcare and to healthcare policy makers to have trustworthy information about new healthcare products (either pharmaceuticals or new diagnostic or treatment techniques) enabling them to decide more rationally about whether or not to include those products in the services they provide to the users of the healthcare system.4,5
Economic evaluation is a technique by which one identifies, measures, values and compares different alternatives in terms of their costs and consequences.6 Economic evaluation can be applied specifically to pharmaceuticals in a study area also known as pharmacoeconomics, as well as to other products and services in the healthcare sector, either meant to diagnose, treat or manage a medical condition.
Health economic evaluations aim to assess the economic advantage, i.e. as value for money, of a new drug or a new intervention by generating evidence showing that the health benefits are significant in relation to the benefits generated by the previously existing therapeutic alternatives and that implementing the new product would have costs that are bearable by the society when compared to the benefits arising from its use.6 In the cases where, from the comparisons, the new technologies produce savings there are no doubts regarding the need for its adoption because resources are going to be freed for other uses in society.
Economic Evaluation of Parkinson’s Disease Treatments
To assess whether a given product provides economic advantage when compared to the existing alternatives, researchers conduct economic analysis. Thus the three main techniques used are cost-effectiveness analysis, cost-utility analysis and cost-benefit analysis. Other types of analysis can be performed in health economics, but these three techniques are the ones considered as complete, for they achieve the full purpose of an economic evaluation, which is to compare at least two alternatives both in terms of their costs and consequences.6
Several studies have been conducted that evaluate economic advantages of PD treatments. The most frequent economic evaluations of PD treatment are cost-effectiveness analysis where alternative therapeutic treatments are compared. With the advent of new forms of treatment for PD, such as surgical approaches as deep brain stimulation, for instance, new areas of study emerge to be addressed by economic evaluation studies.7 Therefore, this is an area in which economic analysis are to flourish. However, the purpose of this article is to focus on the study of PD cost of illness.
Cost of Illness
In cost of illness studies, researchers identify and measure the total costs attributable to a specific disease. Information arising from these studies may be included a posteriori in economic evaluations that compare alternative interventions and is of great value while estimating the economic burden of the disease studied.5
When assessing illness direct costs, two types should be included: direct medical costs and direct non-medical costs. Direct medical costs are the ones more easily identified, these being the costs of medical interventions (whether given at first treatment or in subsequent interventions) such as: medical appointments; hospitalisations; community care; follow-up consultations; diagnostic procedures; pharmaceuticals; medical equipment, etc. Costs generated by use of other therapeutic interventions, such as nursing, physio-, occupational – or speechtherapies are also considered as being direct medical costs. Direct nonmedical costs are the ones that derive from other special interventions that are necessary due to the analysed illness and that are not provided by health specialists. Assessment of direct non-medical costs includes quantification of costs spent by patients or their caregivers with home or car improvements; special dietary needs; or time and/or money spent while travelling to the hospital, medical appointments, 6 etc.
It is of most relevance, especially when considering illnesses such as PD, that the time spent by informal caregivers providing care to patients is assessed, whether as working time lost or as leisure time lost.
By indirect costs of an illness one considers the costs for lost productivity. Productivity losses can be due to illness-related morbidity: costs of early retirement due to illness, absenteeism or temporary work-leaves; and also to mortality from illness. Morbidity and mortality costs are conceptually different and should be presented separately. The economic burden of mortality due to an illness can be estimated in terms of the value of the life years lost attributable to the disease, for example.8
Sources for Costs Assessment
In costs of illness studies, information about costs can be obtained either from pre-existing databases: government or insurance companies’ data on healthcare use; national health inquiries; data on pharmaceutical prices, etc.; and/or they can be obtained through inquires performed on patients, caregivers or health professionals.6
Cost of Illness Studies of Parkinson’s Disease
In Table 1, a synthesis of the results of 11 studies is presented. Those are cost of illness studies in PD for 11 countries (Austria; Czech Republic; Finland; France; Germany; Italy; Portugal; Russia; Sweden; UK and US) and were published between 1998 and 2011. Four studies account only or mainly for direct costs of PD; seven studies assess indirect costs as well as direct costs of PD. Generically, the authors concluded that costs of PD increase with disease progression, more need for healthcare service or caregivers support, and greater impairment of PD patients to perform everyday activities or work. Costs estimated for PD vary from country to country and according to the methodology used, but overall the importance and magnitude of health and economic burdens of PD is clearly visible.
Published studies presenting cost of illness information for PD, as expected, unveil many differences as to what methodological decisions and costs measurements are concerned. The difficulties in the assessment of indirect costs due to PD were evident, moreover in studies with higher number of subjects enrolled. Direct medical costs are more easily quantified and assessed and account for a substantial part of total costs, especially hospitalisations and pharmaceuticals. However, indirect costs of PD are also significant and its quantification is of great worth. PD prevalence, severity and course of progression pose a significant burden on those who suffer from it, patients and their caregivers, as well on health and social services and on society as a whole. The costs associated with informal care represent a significant share of the total costs for society. It should be noted that those costs fall on elderly spouses or working-age children. The burden assumed by informal caregivers highlights the importance of using a societal perspective when estimating the economic burden of PD.