Despite Parkinson disease (PD) affecting more than 4 million people world wide [1
], little is known about the rate of disease progression, the costs of medical and allied health management, or which measures best quantify change over an episode of care. This trial protocol presents the methods that will be used to map disease progression in PD, as well as to identify valid clinical and economic measures for quantifying the natural history and progression of this debilitating condition.
Parkinson's disease is a chronic and progressive condition that is usually diagnosed in adults over the age of 60 years. The incidence of PD is estimated to increase from 1.4 percent of those aged 65–75 years to 4.3 percent of people aged over 85 years [2
]. The rapidly ageing population throughout developed countries means that the number of people with diagnosed PD will quickly increase over the next 20 years. In addition to the impairments, activity limitations and participation restrictions that accompany PD, older adults may experience a range of age-related co-morbidities. Therefore, elderly people with PD can be very prone to complications such as falls, pneumonia and psychosis which can add substantially to the already high social and economic burden of the disease.
A recent literature review of cost of illness studies in Europe relating to PD reported that the annualized direct costs per patient ranged from €5,000 to €10,000 in 2002 [4
]. Significant contributors to direct health system costs include medication and medical and allied health services [5
], with a recent Australian prospective cohort study finding that pharmaceutical expenses contributed approximately 35% of total health care costs [5
]. Individuals and their carers also face significant home care costs, and productivity losses [8
]. Whilst cost of illness studies indicate disease burden at a population level, this information is only relevant where alternative treatment pathways exist, and comparison then undertaken using cost effectiveness methodologies.
Parkinson disease affects the basal ganglia deep within the brain, leading to a reduction in the size and speed of sequential movements, particularly for motor skills [9
]. These activities are normally performed automatically, such as walking, balance, postural control, bed mobility, manipulative tasks, speech, conversation and swallowing [10
]. The basal ganglia also automate cognitive events, mood and behaviour [12
]. Dysfunction in these domains can result in difficulty with driving, shopping, attending to financial matters, conversations, mood and relationships [13
]. The disease can eventually involve other brain areas which control bowel, bladder, blood pressure, sleep, mood and cognition. Although no cure exists, treatment is available for the symptoms of PD, particularly for movement disorders.
Medication compensates for the reduced levels of dopamine in the brain and increases the size and speed of automatic movements [14
]. Unfortunately because of the progression of the disease, benefits diminish and unwanted movements develop which can further impair activity, participation, and well-being [14
]. Typically this takes place around 3–5 years after medication is commenced. People can then experience fluctuations in mobility, often unpredictably, making life very difficult and requiring more assistance. For these reasons, some clinicians advocate an inter-professional team approach to the management of the complex array of disorders of movement, cognition and autonomic function [16
]. Because PD is progressive, management incorporates evaluation of the rate of progression of impairments, activity limitations and participation restrictions [20
]. Treatment aims to limit the rate and level of progression to enable people with PD and others in their lives to enjoy the highest possible quality of life [21
The study will be conducted in Melbourne Australia, the home of the Victorian Comprehensive Parkinson Program (VCPP). The VCPP incorporates several large inter-professional teams, a specialist knowledge base, health professional training in best practice, and long term experience in management of problems experienced by those with PD. The specialist knowledge base includes pharmacological knowledge and the patho-physiology of PD symptoms, manifestations and management. It also includes a specific, evidence-based rehabilitation program which aims to enable people with PD to perform normal movements when these are not possible in the setting of medication failure or ineffectiveness. This rehabilitation program is shared by all disciplines and acts as a common language for the patients irrespective of the team member. The program has a proactive approach to management, identifying problems early and instituting appropriate management. All contact points are managed by expert multi-disciplinary teams. People with PD are empowered to make decisions about their own health care and to be actively involved in management under supervision of relevant team members.
The VCPP is an example of one model of care that embraces this philosophy by providing high quality inpatient, outpatient and home-based services from a specialist inter-professional team of clinicians and clinical researchers. It provides services for more than 1500 patients within a 30 km radius and has 2–4 new referrals per week, providing a unique opportunity for clinical research. The team includes neurologists, physical therapists, occupational therapists, speech pathologists, social workers, psychologists, nurses, dieticians and general medical practitioners. Before service provision models such as this can be comprehensively evaluated, there is a need for preliminary investigations to determine the best measurement tools to quantify therapy outcomes and program costs. Further data are also needed to map disease progression in a sample of people with PD from this service, providing a frame of reference against which inter-disciplinary therapy outcomes can later be evaluated. The study protocol presented in this paper aims to address these needs as the first step in measuring the outcomes and costs of an inter-professional team model for the comprehensive management of people with PD.
Thus the key aims of this initial "proof of concept" investigation are to:
(i) Determine which tests and measurement procedures best capture the multi-dimensional and progressive nature of PD, including clinical effectiveness measures and cost related measures;
(ii) Use this robust test battery that is sensitive to the manifestations of PD to quantify the outcomes of disease progression over a sample period of 12 months in a large sample of people from the VCPP;
(iii) Quantify resource use and costs associated with the management of PD from health system and societal perspectives; and
(iv) Develop a regression model to predict the statistical importance of clinical outcome and quality of life (QoL) measures on cost and health care utilization over a 12-month period.
The key research questions are:
(i) What is the natural history of disease progression in the impairment, activity, participation, well-being, and quality of life domains over a 12 month period in a sample of people receiving inter-disciplinary services from the VCPP?
a. Which field-tested protocols and outcome measures best quantify disease progression for use in future clinical trials of new and/or current interventions for the management of PD?
b. How does quality of life for people with PD change with disease progression?
c. How does caregiver strain change with disease progression?
(ii) What are the costs of care (including informal care, services utilized and events attributable to PD by initial disease state and progression from both a health system and societal perspective) for people with PD receiving care from VCPP?
This involves the establishment of a database to store large volumes of costing and clinical data from multiple sources, and the development of a model to predict the statistical importance of clinical outcome and quality of life measures on cost and health care utilization over a 12-month period for the VCPP.