Introduction

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Parkinson's disease has a prevalence of about 1.6 per 1000 in the United Kingdom, therefore the average UK general practitioner with 1900 patients will care for only three patients with the condition.^1-3 Its management is complicated by a widening range of drug types and by patients with advanced disease requiring a multiplicity of aids and therapies, including adaptations to the home, referral for speech therapy, physiotherapy, and occupational therapy, and visits to day centres and hospital outpatients. ^{4 5}

The role of nurses specialising in Parkinson's disease has developed over the past 10 years.⁶ These nurse specialists were initially promoted by consultants with an interest in Parkinson's disease in response to the need for coordination of their patients' education, monitoring, and care (box), but their effectiveness has not been evaluated comprehensively.^7-9 We evaluated the effects of nurse specialists working with general practitioners on the health outcomes and healthcare costs of patients with Parkinson's disease.

	Methods

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Recruitment
Our sampling frame included all English health authorities coterminous with local authorities in 1995 that did not already have well developed community based services of nurse specialists in Parkinson's disease. After random selection, we recruited nine health authorities (see bmj.com).

We approached all the general practices in the nine areas and asked them to identify patients with a diagnosis of Parkinson's disease from their doctor or hospital. Eligible patients were those taking one or more antiparkinsonian drugs. They were invited to take part by letter from either their doctor or us. We excluded patients aged 17 years or less or those with severe mental illness or cognitive impairment sufficient (in the view of their doctor) to preclude valid informed consent.

Statistical power and randomisation
With an expected dropout rate of 15% in each year of the trial, we determined a total initial sample size of 1600 patients could detect a 10% change in a categorical outcome having an initial prevalence of 50%, with 80% power at the 5% significance level. Patients were randomised within practice by using block randomisation lists that reflected the randomisation ratio of the health authority area (see bmj.com).

Nurse intervention
Nine nurses were employed by the university and trained at the Nursing and Midwifery School, University of Sheffield. They completed a course on meeting the special needs of people with Parkinson's disease and their carers.¹⁰ In the trial their clinical position in the community was advisory to the general practitioner rather than clinically autonomous. Each nurse was supplied with a leased car and a mobile phone and assumed areas of responsibility (box) under the guidance of a nurse manager. Their working pattern was characterised by a time use study in which the nurses kept a diary of their daily work over two one week periods. Patients in the control group were not provided with additional services until the end of the two year intervention, when they were offered one assessment from a nurse specialist.

Baseline and follow up assessments
Trained lay interviewers collected information relevant to health outcome and costs at baseline and at one and two years. Before each interview the patients were sent a questionnaire eliciting information about self perceived health status.

Self completed questionnaire
The questionnaire included a validated instrument for measuring the functioning and wellbeing of patients with Parkinson's disease, the PDQ-39, and the Euroqol, a health related quality of life measure.^11-14 The questionnaires at one and two years also included a self perceived global health question asking patients about change in their general health over the preceding 12 months. This question is used by clinicians specialising in Parkinson's disease to gauge patient perception of changes in wellbeing between visits to hospital clinics. The five possible responses to this question were much better (score 0), better (1), same (2), worse (3), and much worse (4). Because the response in the second year depends on the response in the first year, a score was derived representing an individual's change in health over the two year period (see bmj.com). The score ranged from 0 (best) to 8 (worst).

Interviews
Face to face interviews covered three broad groups of questions: assessment of clinical outcome measures, use of health and social services, and personal characteristics. Clinical assessment included questions relating to duration and severity of disease and a test of patients' ability to put dots in a grid of 90 squares within 30 seconds (dot in square test).¹⁵ The Columbian rating scale was used to test patients' ability to rise from a chair with a hard seat to allow "push off."¹⁶ Adverse events such as fractures were also recorded.

Costs
Services, aids, and adaptations to the home were valued by using data compiled by the Personal Social Services Research Unit and priced at 1996 costs¹⁷; drugs were priced from the Monthly Index of Medical Specialities 1996 net ingredient costs.¹⁸ For all these elements average costs were calculated by summing the unit cost per patient, annualising where appropriate, and dividing the total by the number of patients in the study. Costs incurred by carers are not reported here.

The interviews were repeated at one and two years. Follow up of mortality continued for 4 years (to 31 December 1999).¹⁹

Statistical analysis
We estimated between group differences using ordinal logistic regression for progression on stand-up test, logistic regression for bone fracture, ordinary linear regression for dot in square scores and quality of life measures, and Cox regression for mortality. For each patient we calculated the changes in healthcare cost (excluding costs for carer and social security benefit) over the two years.

	Results

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Participant flow and follow up
Of the 863 eligible practices, 438 (51%) agreed to participate and 1859 patients with Parkinson's disease were randomised (figure). No noticeable differences were observed between treatment groups at baseline (table 1).

View larger version (33K): [in this window] [in a new window]   Participant flow through study

At the end of the study, patients showed a decline in health status (see bmj.com). The average self perceived health score as assessed by the global health question was 4.89, another indicator of deterioration; unchanged self perceived health over 2 years would score 4 on this question.

Primary outcomes

Objective measures of health
At two years' follow up the severity of Parkinson's disease, the proportion of each group sustaining a fracture, and mortality was not significantly different between the two groups (table 2).

Patient wellbeing
No differences were observed in Euroqol scores or in any dimension of the PDQ-39 at the end of the study (see bmj.com). However, when the patients were asked about change in general health in the global health question, the combined scores from years 1 and 2 differed between groups, with the nurse group doing significantly better than the control group (difference in means -0.23, 95% confidence interval -0.4 to -0.06).

Costs
The mean annual cost among the nurse group increased from £4050 in the year preceding the study to £5860 in the second year of the study and from £3480 to £5630 among the control group, the difference in mean increase between groups not being significant (table 3). The mean costs of different components of health care were also similar in each group during the second year; the provision of nurse specialist care cost £200 per patient per year.

Nurse activity
The time use study showed that the nurse specialists assessed an average of 14 patients per week, 75% at home, 14% at general practices, and 11% in hospital consultant clinics. Patients in the nurse group received on average eight assessments by the nurse per year. In a typical week the nurses made five visits to general practitioners, two to carers, and one to a consultant to discuss patient care. Apart from face to face contact, considerable amounts of nurse time were spent each week on administration, letter writing, telephoning patients (6 hours), and travelling (8.4 hours).

	Discussion

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An earlier hospital based study found that patients with Parkinson's disease subjectively valued nurse specialists although their psychosocial functioning did not improve.⁹ Our study, the largest carried out to date and the only one to be based in primary care, mostly agrees with that study as well as with the recent hospital based randomised trial of 185 patients with Parkinson's disease, which found no evidence of a nurse specialist effect on a range of self reported health outcomes.²⁰

As with any trial of randomisation within general practice, contamination of controls from the spill over effects of the intervention cannot be entirely excluded. Evidence of contamination was sought, but not found, from analysis of within patient changes in the mobility dimension of the PDQ-39. One nurse specialist and one control patient were randomly selected from each participating practice and their scores regressed on practice size (on the assumption that the larger the number of study patients from each practice the greater the likelihood contamination would occur), but no significant difference was found between the nurse and control groups.

The trial intervention used nurses who had only recently trained in nursing patients with Parkinson's disease. They were therefore on a professional learning curve and may not be representative of experienced nurse specialists. Another limitation of our pragmatic trial was the reliability of case ascertainment when based on general practice records and information systems. A recent cross sectional prevalence survey of idiopathic Parkinson's disease in 15 general practices across London showed that 54 of 241 (22%) patients whose records contained either a diagnosis of Parkinson's disease or parkinsonism, prescription of antiparkinsonian drugs, or mention of tremor after the age of 50 years had no form of parkinsonism.³ Although it is likely that some patients with non-Parkinson's disease entered our trial, randomisation minimised the likelihood of bias by distributing such patients proportionately in both arms.

Conclusion
Although our study found no significant differences in health outcome between patients receiving care from a nurse specialist and those receiving standard care from their general practitioner, there was a significant improvement in subjective wellbeing of patients cared for by a nurse. Our study was of sufficient size to detect important changes, and the measured decline of health in the group as a whole confirms that the instruments used were appropriate.²¹ The benefit in subjective wellbeing is an important finding, especially in a condition such as Parkinson's disease where decline is generally relentless.²² This improvement was achieved without an increase in healthcare costs.