Original Article
Recruitment rate for a clinical trial was associated with particular operational procedures and clinician characteristics

https://doi.org/10.1016/j.jclinepi.2013.08.007Get rights and content

Abstract

Objectives

Expenditure on research has grown substantially; however, a major challenge for conducting successful clinical research is the efficient recruitment of participants. We investigated factors influencing the rate at which general practitioners (GPs) recruit participants to a randomized controlled trial.

Study Design and Setting

We used data on 363 GPs recruiting participants for a randomized controlled trial of low back pain. Multivariate negative binomial regression was used to determine associations of characteristics of the GP and study operational aspects with the recruitment rate.

Results

GPs recruited 1,195 participants at a rate of 0.013 participants/day. GPs located in a high socioeconomic area recruited at half the rate as those located in a low socioeconomic area [incident rate ratio (IRR), 0.52; 95% confidence interval (CI): 0.37, 0.74]. A follow-up within 2 weeks of training the GP and a higher number of face-to-face visits were operational procedures associated with a higher rate of recruitment (IRR, 2.15; 95% CI: 1.58, 2.94 and IRR, 1.17; 95% CI: 1.11, 1.24, respectively). Other contacts made with a GP were not associated with recruitment.

Conclusion

The results suggested that the type of operational procedures used in clinical trial recruitment strategies are important aspects to consider. The ability to predict which GPs will recruit based on GP characteristics seems limited.

Introduction

What is new?

Key findings

  1. •

    The number of face-to-face visits and a prompt follow-up after the initial study training were associated with higher recruitment rate. Other methods of correspondence with recruiting clinicians had no association.

  2. •

    One clinician characteristic (socioeconomic status of the clinic suburb) was associated with the recruitment rate.

What this adds to what was known?
  1. •

    The types of operational procedures are important considerations for improving the recruitment rate to a large clinical trial.

  2. •

    The ability to predict which general practitioners (GPs) will recruit based on GP characteristics seems limited.

What is the implication and what should change now?
  1. •

    Understanding the effectiveness and cost-effectiveness of manipulating these aspects is required.

Although one of the major challenges for health researchers has been how to successfully fund research, once funding has been obtained, significant difficulties in the conduct of the research may arise. In October 2009, Australia spent $121.4 billion on health, this representing 9.4% of gross domestic product. Of this, the area of expenditure with the highest percentage growth was health research, which grew by 10.8% in real terms [1]. The substantial growth in research activity meant that there are now many researchers facing the challenges inherent in conducting clinical research. One of the greatest challenges is how to successfully recruit participants for large clinical trials.

Previous research has suggested that problems with recruitment are a major reason for the failure of clinical research leading to wasted research funding [2]. More than 50% of studies require a funding extension because of recruitment issues and more than one-third do not achieve their original recruitment target [3]. Slow recruitment can lead to excessive costs to complete the study [4]. Inconsistent recruitment among study sites may lead to unrepresentative study samples being collected. Failure to recruit an adequate number of participants may deliver equivocal results because the study is underpowered [5], [6]. Ultimately, any of these scenarios may limit the ability of clinical research to improve health outcomes. The potential consequences and costs of failed clinical research because of poor recruitment highlight the urgent need to identify strategies that will optimize recruitment.

Recruiting subjects to clinical trials in the primary care setting presents unique challenges because primary care studies frequently rely on practicing clinicians to screen and enroll patients. Although patient choice is a key driver of recruitment success, many other factors present significant barriers. Primary care clinicians are often time poor, which significantly hinders their ability to recruit [7]. Inadequate training in the study protocol, loss of autonomy, concerns with the study methods (e.g., use of placebos, blind treatment allocation), issues in gaining informed consent, and concerns that inviting patients to participate in research negatively affects the patient–doctor relationship have also been reported as recruitment barriers for clinicians [8]. The range of barriers that apply to different clinicians working in independently managed practices underpins the challenge of recruiting through primary care.

At present, there is a paucity of useful research investigating strategies to overcome barriers and improve recruitment to clinical studies in primary care [9]. Many proposed strategies are not useful because they involve modifications to the study protocol, which may negatively impact on trial quality [9], [10]. Other strategies are only designed to address a specific barrier in a specific study and lack generalizability to other trials [11]. There is a need to develop and assess strategies that can be applied to different studies to improve the efficiency of participant recruitment for future research in primary care.

This study aimed to identify factors associated with general practitioners (GPs) recruiting patients with acute low back pain to a randomized controlled trial evaluating paracetamol. We investigated two different types of factors: characteristics of the GPs (e.g., demographic factors such as age, socioeconomic index of the suburb of practice, clinical experience) and operational aspects of the study (e.g., routine screening of patients by GPs, regular site visits by trial staff).

Section snippets

Study design

We studied GPs enrolling patients with acute low back pain to a double-blind randomized placebo controlled trial between November 2009 and June 2012. The trial methods and procedures for recruitment of patients have been published elsewhere [12]. Ethical approval for the trial was granted by the University of Sydney Human Research Ethics Committee. The trial was prospectively registered on the ANZ clinical trial registry (ACTN: 12609000966291).

Setting and participants

The clinical trial utilized practicing primary care

Statistical analysis

Descriptive statistics were carried out to describe recruitment rate for the study, using data from all clinicians (GPs and pharmacists). Descriptive statistics were also performed for characteristics and operational aspects applied to all GPs who participated in the study.

The primary analysis assessed the effect of the candidate variables on the rate of patients recruited by a GP. A rate is defined as the number of events per time. Because each GP commenced the study on different dates, this

Descriptive results

From 3,912 patients screened by 363 GPs and 125 pharmacists between November 2009 and June 2012, there were 1,312 patients randomized into the trial. This was an overall recruitment yield of 34%; however, the average rate of recruitment for clinicians was low (0.005 patients/day of participation). Of the 2,600 patients not taking part, 1,785 (68.7%) did not meet the eligibility criteria and 815 (31.3%) declined to participate. GPs recruited most participants (90.5%) to the study; however, more

Summary of findings

Our study found five variables that were statistically associated with the rate at which GPs recruited patients to the study. Of these, only one GP characteristic (SES) was significant, indicating that identifying GPs likely to recruit at faster rates is difficult. Some simple operational procedures were associated with increased recruitment, and these provide potential strategies to optimize recruitment. GPs who had a follow-up visit within 2 weeks recruited at a rate of 2.2 times greater than

Conclusion

This study identified that certain operational procedures such as prompt follow-up of clinicians after initial training and the number of face-to-face visits provided to clinicians are more strongly associated with increasing recruitment rate than clinician characteristics such as clinician age and experience. Clinicians with practices in the areas of lower SES have higher recruitment rates. These results suggest that operational aspects used in a study are a critical consideration when

References (17)

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Financial disclosure: C.G.M., M.J.H., and J.L. are investigators on a clinical trial evaluating the efficacy of paracetamol for acute low back pain (ACTRN126090000966291). This is an investigator-initiated trial funded by Australia's National Health and Medical Research Council (NHMRC). The trial medicines and supplementary funding are provided by GlaxoSmithKline. C.M.W. scholarship is funded by the NHMRC. C.G.M. and J.L. hold research fellowships funded by the Australian Research Council. C-.W.C.L. holds a research fellowship funded by the NHMRC.

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