Recruitment issues when primary care population clusters are used in randomised controlled clinical trials: Climbing mountains or pushing boulders uphill?

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Abstract

Cluster randomised controlled trials for health promotion, education, public health or organisational change interventions are becoming increasingly common to inform evidence-based policy. However, there is little published methodological evidence on recruitment strategies for primary care population clusters. In this paper, we discuss how choosing which population cluster to randomise can impact on the practicalities of recruitment in primary care.

We describe strategies developed through our experiences of recruiting primary care organisations to participate in a national randomised controlled trial of a policy to provide community breastfeeding groups for pregnant and breastfeeding mothers, the BIG (Breastfeeding in Groups) trial. We propose an iterative qualitative approach to recruitment; collecting data generated through the recruitment process, identifying themes and using the constant comparative method of analysis. This can assist in developing successful recruitment strategies and contrasts with the standardised approach commonly used when recruiting individuals to participate in randomised controlled trials.

Recruiting primary care population clusters to participate in trials is currently an uphill battle in Britain. It is a complex process, which can benefit from applying qualitative methods to inform trial design and recruitment strategy. Recruitment could be facilitated if health service managers were committed to supporting peer reviewed, funded and ethics committee approved research at national level.

Section snippets

Introduction and background

Cluster randomised controlled trials for health promotion, education, public health or organisational change interventions are becoming increasingly common to inform evidence-based policy. Among their advantages, they decrease contamination between cases and controls that may occur with individual patient randomisation and they may improve compliance. Methods for evaluating interventions where the cluster is a geographical area or a health service organisation have previously been reviewed [1],

Deciding which population cluster to randomise and recruit

In primary care, the appropriateness of randomising General Practitioner (GP) practices instead of individual practitioners has been advocated [6], but also criticised because of the risks of contamination [7] and selection bias [8]. Interventions to promote behavioural change applied in defined geographical areas, for example television health promotion adverts, may underestimate effects, as participants may not be individually informed and therefore may have less capacity to benefit than if

Timing, intervention equipoise and recruitment

Ethical issues when randomising population clusters and time delays have been highlighted [13], [16]. In trials where individual patients are randomised, recruitment progresses throughout the trial funding period and may or may not reach the required sample size. In contrast, for population trials nested in large data sets, where before and after outcomes are being compared, the recruitment pressures cluster at the beginning of the trial, together with other administrative tasks. Recruitment

The recruitment process

In trials recruiting individuals, a standardised protocol is usual; however, a qualitative action research approach has been advocated [17]. In contrast, when recruiting primary care organisations, one approach may not suit all and there is little published guidance. Our approach commenced with a standard written invitation to participate which we sent to managers, public health practitioners and relevant stakeholder organisations, with follow-up telephone calls. Thereafter, each organisation

Strategies for recruiting primary care organisations to participate in trials

The iterative qualitative approach to recruitment, data collection and analysis allowed us to compare the official reasons given by organisations for non-participation and the contributing contextual themes raised by potential stakeholders within organisations (Box 2). The approach enabled the development of successful recruitment strategies, which are discussed below, summarised (Box 3) and illustrated with examples from our trial (Box 4).

Ethical considerations

There are important ethical considerations when designing and recruiting for cluster randomised controlled trials, which are discussed in detail elsewhere [21]. To ensure that no individual member of a cluster could be disadvantaged by our trial, we had two levels of informed consent: at primary care organisation level and for individuals attending groups, to consent to the additional data collected at groups. In our feasibility study, concerns were raised about control areas “standing still”,

Conclusion

We have illustrated how the standardised approach to recruiting individuals to trials may not be appropriate when recruiting larger organisations in primary care. The complexity of recruitment increases with the size of organisation. An iterative qualitative approach to recruitment, which has been recommended for controversial trials randomising individuals [17], is valuable and can assist in the development of successful strategies. National primary care recruiting organisations [22], [23] may

Acknowledgements

The BIG trial is funded by The Scottish Executive Health Department, Chief Scientist Office. Pat Hoddinott has a Primary Care Career Scientist Award from the Scottish Executive Health Department, Chief Scientist Office. We would like to thank Jill Mollison, Senior Medical Statistician, Centre for Statistics in Medicine, University of Oxford and Peter Fayers, Professor of Medical Statistics, Department of Public Health, University of Aberdeen for their assistance with trial design. Gordon

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