Recruitment to a prevention trial
S Hamilton¹ JC Craig ²
1. Centre for Kidney Research, Children’s Hospital Westmead NSW
2. Dept. of Public Health and Community Medicine, University of Sydney.
Introduction: Recruitment of sufficient patient numbers to adequately answer the research question is an issue for all randomised controlled trials. Many interventions are used to increase recruitment. The aim of this study is to describe the effect on recruitment and consent rate of increasing the eligible pool and adding a second centre.
Methods: The Prevention of Recurrent urinary tract Infection in children with Vesicoureteric reflux and Normal renal Tracts Trial (PRIVENT), is an NHMRC funded randomised trial that is designed to determine whether long-term antibiotics prevents urinary tract infection in children. Recruitment to PRIVENT has been difficult at times, a common problem among clinical trials, particularly prevention and placebo-controlled trials. The recruitment target for PRIVENT is 16 patients per month, resulting in a total of 780 patients enrolled. In the first year of recruitment 17 eligible patients per month were referred with 3 per month enrolling, a consent rate of 18% (enrolled/eligible). In January 2000 a research fellow was employed and the eligibility criteria was broadened. In September 2000 The Canberra Hospital joined PRIVENT. The effect of these changes have been measured using a before-after study design with the date of the change as the breakpoint, assuming no latency and tested using an unpaired t-test for differences in the mean monthly recruitment and consent rates.
Results: Table 1: Differences in the mean monthly recruitment and consent rates before and after Phase I and Phase II.
| Baseline | Phase I: after eligibility criteria change | Phase II: second centre added | |||
| Total | Change (95% CI; p) | Total | Change (95% CI; p) | ||
| Number of eligible children [a] | 17 | 25 | +8 (3.4 to 15.2; p=0.004) | ||
| Number of enrolled children | 3 | 6 | +3 (0.3 to 5.7; p=0.03) | 8 | +2 (1.0 to 5.5; p=0.17) |
| Consent rate (%) | 18 | 27 | +9 (3 to 21; p=0.09) | ||
| [a] Number of eligible children Sydney site only as Canberra data is incomplete. | |||||
Discussion: Broadening the eligibility criteria and including Canberra as the second major centre resulted in an increase in both the number of patients eligible and the consent rate, resulting in a substantial increase in the number of patients enrolled in the study.
Recruitment to prevention and placebo-controlled trials can be difficult at times. Future studies that take steps to broaden the selection criteria and add further centres will increase their opportunities for recruiting sufficient numbers and reaching their target sample size.
Presented at From Cell to Society 3, Research Conference 2002, College of Health Sciences, University of Sydney, 18 - 19 Sept 2002 Leura, NSW, Australia
Correspondence
Sana Hamilton
Centre for Kidney Research
The Children’s Hospital at Westmead
Locked Bag 4001
Westmead NSW 2145
Sydney Australia
Tel: +61 2 9845 3074
Fax: +6 12 9845 3038
Email:Sana Hamilton