Randomised controlled trials in primary care: case study

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Randomised controlled trials in primary care
case study

• Doctor Sue Wilson
• University of Birmingham
• United Kingdom

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Full Reference

• Randomised controlled trials in primary care
  case study .
• Wilson S, Delaney BC, Roalfe A, Roberts L,
  Redman V, Wearn A, Hobbs FDR. British Medical
  Journal. 200032124 27 (1 July).

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About the Author.

• Senior Research Fellow
• Public Health / Cancer Epidemiology background
• Interested in design and conduct of high quality
  research within Primary Care

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Learning Objectives

• To understand the importance of research in
  Primary Care
• To develop an awareness of issues surrounding
  randomised controlled trials in a primary care
  setting

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Performance Objectives

• To demonstrate awareness of some of the
  difficulties associated with research in Primary
  care (e.g. patient / practice recruitment and
  randomisation)

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How will we address this topic?

• This lecture will discuss some of the issues
  that must be considered when conducting and
  interpreting the results of trials in primary
  care using examples generated during a trial of
  the management of dyspepsia.

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Background to the Lecture

• Why choose Dyspepsia?
• Chronic disease
• Largely managed in primary care
• Requires high quality evidence from randomised
  trials

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Background continued

• The Research Question
• Is open access endoscopy more effective and
  efficient than routine out patient referral for
  the management of dyspepsia?

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Birmingham Open Access Endoscopy Study

• Eligible subjects
• Dyspeptic patients (age 18)
• Randomised by sealed envelope
• Control usual management - NOT open access
• Study intervention depends on age

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Why do trials in Primary Care?

• Over 90 of patient contacts in NHS occur in
  Primary Care
• Relevance of research undertaken in secondary or
  tertiary care is questionable

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Recruitment Bias

• Amount of Practitioners vs. time / cost of
  recruitment / maintenance of practitioners
• Number of patients with relevant condition vs.
  total consultations
• Participation of Practices / Practitioners in a
  defined area

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Success in recruiting practices
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Z 4.4, Plt0.0001
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Recruitment Bias (patients)

• Eligible patients not asked /not prepared to
  enter study
• Differences in prevalence / presentation rates
• Differences in proportion of eligible patients
  recruited

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Factors affecting recruitment rates

• Interest in trial may wane after initial period
• Eligible cases will be restricted to incident
  disease once pool of prevalent cases have been
  recruited

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Case definition Standardised monthly recruitment
rate by duration of participation
4.5
4
3.5
Recruitment Rate per 10,000
3
population
2.5
2
1.5
1
0.5
0
0
10
20
30
40
Time since practice recruited (months)
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Ethical Issues and recruitment

• Patient may feel obligated to participate
• Financial implications to GP
• Conflict between randomisation options and
  preferred course of management
• Patient acceptance of randomisation or outcome of
  randomisation

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Selective recruitment of patients

• Impact of Randomisation process on results
• Complexities in randomisation / reduced patient
  recruitment
• Recruitment levels and Practice workload

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Selective recruitment of patients continued

• Practice commitment
• Use of research staff for recruitment

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Practice Recruitment Rate Symptom Score at time
of recruitment
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16
14
Monthly Recruitment Rate per 10,000
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population
10
8
6
4
2
0
0
5
10
15
20
Mean Symptom Score
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Does representativeness matter?

• Not at all?
• Trials have always been selective
• Its up to others to determine local applicability
• Very much?
• Raison detre of primary care trial

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Does representativeness matter?(continued)

• To some extent?
• Balance to be achieved
• Modelling helps generalise and particularise

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References