Recruiting older people for research through general practice: the Brief Risk Identification Geriatric Health Tool trial

AIM

To describe successful methods of recruitment and identify practice characteristics related to increased recruitment of older people for a randomised controlled trial.

METHODS

General practices in three regions of New Zealand and community-dwelling patients aged 75+ were recruited for the Brief Risk Identification Geriatric Health Tool trial. General practitioners (GPs) were faxed invitations with telephone follow-up. Reply-paid cards with telephone follow-up were used to invite older people. GP and practice characteristics were examined in relationship to recruitment rate.

RESULTS

During 2007-2008, 158 of 438 GPs (36%) in 60 of 116 practices approached (52%) were recruited. Regional variation was marked and 3893 of 8308 invited (49%) older people were recruited. The GP's length of time at the practice and training in New Zealand was associated with recruitment success.

CONCLUSIONS

Despite variability in practice recruitment, a reasonably large and representative sample of older people was recruited through general practices.

Intraclass correlation coefficients from three cluster randomised controlled trials in primary and residential health care

OBJECTIVE

This paper provides intraclass correlation coefficients (ICCs) for estimation of sample size inflation required in future cluster randomised trials in primary or residential care.

METHODS

Three cluster randomised trials were conducted among middle-aged and older adults in primary care and residential care in Australia and New Zealand between 1995 and 2002. Baseline means or proportions, mean change, and ICCs with their standard errors and 95% confidence intervals are reported for outcome variables used in the three studies. The ICCs were estimated from a one-way random effects model using the analysis of variance method.

RESULTS

ICCs for quality of life and psychological variables in the primary care studies were low (below 0.018). ICCs for clinical and physical activity variables ranged from 0 to 0.08. ICCs for health and functional status in residential care for the elderly were high, ranging from 0.025 to 0.514.

CONCLUSIONS

The magnitude of the intraclass correlation varies with the venue of the trial, the outcome variables used, and the expected effect of the intervention. However, the intraclass correlations provided will be useful for more appropriate planning of residential and primary care-based trials in the future.