Format

Send to

Choose Destination
See comment in PubMed Commons below
BMC Med Res Methodol. 2007 Jul 3;7:30.

The Hawthorne Effect: a randomised, controlled trial.

Author information

1
Department of Psychological Medicine, Imperial College London, UK. robmccarney@googlemail.com <robmccarney@googlemail.com>

Abstract

BACKGROUND:

The 'Hawthorne Effect' may be an important factor affecting the generalisability of clinical research to routine practice, but has been little studied. Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge, no attempt has been made to quantify them. Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia.

METHODS:

Participants in a dementia trial were randomised to intensive follow-up (with comprehensive assessment visits at baseline and two, four and six months post randomisation) or minimal follow-up (with an abbreviated assessment at baseline and a full assessment at six months). Our primary outcomes were cognitive functioning (ADAS-Cog) and participant and carer-rated quality of life (QOL-AD).

RESULTS:

We recruited 176 participants, mainly through general practices. The main analysis was based on Intention to treat (ITT), with available data. In the ANCOVA model with baseline score as a co-variate, follow-up group had a significant effect on outcome at six months on the ADAS-Cog score (n = 140; mean difference = -2.018; 95%CI -3.914, -0.121; p = 0.037 favouring the intensive follow-up group), and on participant-rated quality of life score (n = 142; mean difference = -1.382; 95%CI -2.642, -0.122; p = 0.032 favouring minimal follow-up group). There was no significant difference on carer quality of life.

CONCLUSION:

We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia resulted in a better outcome than minimal follow-up, as measured by their cognitive functioning.

TRIAL REGISTRATION:

Current controlled trials: ISRCTN45577048.

PMID:
17608932
PMCID:
PMC1936999
DOI:
10.1186/1471-2288-7-30
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for BioMed Central Icon for PubMed Central
    Loading ...
    Support Center