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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
Citation preview
Randomised controlled trials in primary care: case study
Doctor Sue WilsonUniversity of Birmingham
United Kingdom
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. 2000;321:24 – 27 (1 July).
About the Author….• Senior Research Fellow
• Public Health / Cancer Epidemiology background
• Interested in design and conduct of high quality research within Primary Care
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
Performance Objectives• To demonstrate awareness of some
of the difficulties associated with research in Primary care (e.g. patient / practice recruitment and randomisation)
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.
Background to the Lecture
Why choose Dyspepsia?• Chronic disease
• Largely managed in primary care• Requires high quality evidence
from randomised trials
Background continued
The Research QuestionIs open access endoscopy more
effective and efficient than routine out patient referral for
the management of dyspepsia?
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
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
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
Success in recruiting practices N %
Practices contacted 90
Practices expressing interest 59 65
Practices ‘recruited’ 43 48
Practices recruiting a patient 31 34
Practices recruiting 5+ patients 23 26
Practice Characteristics
Active practices (n=31)
Eligible, not participating (n=216)
Wilcoxon rank sum test
No. of partners
Median (IQR) 3 (2 to 6) 2 (1 to 3)
Mean (SD) 3.8 (2.2) 2.2 (1.6)
Townsend score:
Median (IQR) 1.8 (-0.9 to 4) 4.4 (1.0 to 6.3) Z = -3.2, P<0.01
Mean (SD) 1.5 (2.8) 3.8 (7.4)
Z = 4.4, P<0.0001
Recruitment Bias (patients)• Eligible patients not asked /not
prepared to enter study• Differences in prevalence /
presentation rates• Differences in proportion of
eligible patients recruited
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
Case definition: Standardised monthly recruitment rate by
duration of participation
00.5
11.5
22.5
33.5
44.5
0 10 20 30 40Time since practice recruited (months)
Rec
ruitm
ent R
ate
per 1
0,00
0 po
pula
tion
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
Selective recruitment of patients
• Impact of Randomisation process on results
• Complexities in randomisation / reduced patient recruitment
• Recruitment levels and Practice workload
Selective recruitment of patients continued
• Practice commitment• Use of research staff for
recruitment
Practice Recruitment Rate & Symptom Score at time of recruitment
02468
1012141618
0 5 10 15 20Mean Symptom ScoreM
onth
ly R
ecru
itmen
t Rat
e pe
r 10,
000
popu
latio
n
Does representativeness matter?
• Not at all?–Trials have always been selective–Its up to others to determine local
applicability• Very much?
–Raison d’etre of primary care trial
Does representativeness matter?(continued)
• To some extent?–Balance to be achieved–Modelling helps generalise and
particularise
References