Descriptive epidemiology of Parkinsons disease

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Descriptive epidemiology of Parkinsons disease

• Carl Counsell
• Clinical Senior Lecturer in Neurology

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Introduction

• Parkinsonism
• bradykinesia
• rigidity
• tremor
• postural instability
• Commonest cause idiopathic Lewy body
  Parkinsons disease (PD)

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Introduction

• PD 2nd commonest neurodegenerative disease
• Crude prevalence 150-300 per 100,000
• (1,600 per 100,000 over 65)
• Cost in UK 750 million/year
• Aetiology unknown

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Incidence studies

• Health service planning
• Epidemiological research
• Prognostic studies in representative cohort

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Systematic review of incidence studies in PD

• Medline/Embase/Science Citation reference lists
• Full text, English language studies giving
  incidence figure for PD or Parkinsonism
• 2 independent assessors
• Data extraction methods results

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Incidence studies in PD results

• N 22
• 1935 to 1996
• USA (5), UK (4), N. Europe (5), Medit (4), E Asia
  (2), N Africa (1), Australia (1)

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Incidence studies in PD quality

• Case ascertainment variable (4/22 only GP or
  hospital)
• Case screening 6/22 no expert examn
• Incident case 8/22 Sx onset
• 9/22 date of Dx
• Inclusion criteria variable (6/22 not explicit)
• Prospective 9/22
• Follow up 0/22
• Histology 2/22

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Incidence figures

• Crude 1-26 per 100,000
• Standardised 8-20 per 100,000
• (similar methods)

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Prognosis of PD

• Mortality
• Progression of disease
• impairment
• disability
• QoL
• Complications
• Carer

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Sources of data on prognosis

• Community-based inception cohort
• Follow-up of community-based prevalence cohorts
• Follow-up of hospital-based cohorts
• Cohorts from randomised trials

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Mortality

• 3 community prevalence cohorts
• - RR 2-3
• 2 hospital-based cohorts
• - no increase

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Impairment progression

• Limited to hospital-based prevalence studies
• Often small, short follow-up
• Progression of bradykinesia, rigidity, postural
  instability but not tremor

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Disability progression

• 2 pre-levodopa hospital-based studies
• 1. 60 dead/disabled at 5-9 yrs
• 2. 60 independent at 10 yrs
• 3. 10 benign
• Modern era
• RCT 70 dead/ disabled at 10 yrs
• Prevalence studies 40 some disability
• 30 institutionalised

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Complications

• All hospital-based cohorts or RCTs
• ? 50 motor fluctuations after 5 yrs
• ? 30 develop depression
• ? 30 develop dementia after 10 yrs

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Prognostic factors

• Poorly studied
• Older age at onset
• Non-tremor dominant
• ? male
• Dementia

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What is required?

• Further incidence studies with comparable methods
• prospective (with some follow-up)
• standard inclusion / exclusion criteria
• overlapping search strategies
• expert review
• standardised results (age, diagnosis, seen, ?
  histology
• Long-term follow-up (to death) of inception
  cohort
• Systematic reviews of prognosis

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Grampian study

• Aim
• To identify and review all patients from
  Grampian with symptoms/signs suggestive of recent
  onset (lt3yrs) Parkinsonian disorder over 5 year
  period and follow them up at yearly intervals
  thereafter. Confirm diagnosis pathologically in
  as many as possible.

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Why Grampian?

• Stable population of ?optimal size
• Epidemiological/HSR/neurological expertise and
  interest
• Good collaboration with GPs
• Previous PD prevalence study
• Time
• Imaging pathology

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The need for a pilot study

• Case ascertainment (rigorous but feasible)
• GP referrals reminders, computerised searches,
  visits
• Hospital outpatients / admissions (private)
• PD nurse referrals
• Rehab / day hospital referrals
• Pharmacy records
• Patient support groups
• ?Nursing homes
• False negatives?

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The need for a pilot study

• Diagnostic criteria
• varying dx criteria for Parkinsonism each
  Parkinsonian syndrome
• use the broadest subclassify
• ? include drug-induced Parkinsonism
• Definition of incident case
• sx onset vs diagnosis
• retrospective recall / over-call
• ?date of onset of specific symptoms within 3
  years and features of PD on exam

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The need for a pilot study

• Clinical assessment (before Rx if possible)
• - diagnostic criteria
• - risk factors
• - impairment / disability / QoL
• - cognition / mood
• - carer outcomes (stress, QoL)
• Imaging protocol
• - MRI / SPECT

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The need for a pilot study

• Develop database
• Develop follow-up protocol
• Resources
• Discuss best way to approach brain bank donation

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Conclusions

• Still remarkably few reliable data on incidence
  and prognosis of PD
• Grampian study could make a significant
  contribution to our knowledge

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Additional studies

• Accuracy of different dx criteria
• Role of imaging in dx at different stages
• Risk factor assessment
• Outcome measurement
• Predictive modelling
• Health economic studies
• Genetic studies
• Patho-physiological studies