dc.contributor.author | Goldsmith, KA | en_US |
dc.contributor.author | Chalder, T | en_US |
dc.contributor.author | White, PD | en_US |
dc.contributor.author | Sharpe, M | en_US |
dc.contributor.author | Pickles, A | en_US |
dc.date.accessioned | 2016-10-03T13:27:55Z | |
dc.date.issued | 2018-06 | en_US |
dc.date.submitted | 2016-10-02T09:36:39.509Z | |
dc.identifier.uri | http://qmro.qmul.ac.uk/xmlui/handle/123456789/15687 | |
dc.description.abstract | Clinical trials are expensive and time-consuming and so should also be used to study how treatments work, allowing for the evaluation of theoretical treatment models and refinement and improvement of treatments. These treatment processes can be studied using mediation analysis. Randomised treatment makes some of the assumptions of mediation models plausible, but the mediator-outcome relationship could remain subject to bias. In addition, mediation is assumed to be a temporally ordered longitudinal process, but estimation in most mediation studies to date has been cross-sectional and unable to explore this assumption. This study used longitudinal structural equation modelling of mediator and outcome measurements from the PACE trial of rehabilitative treatments for chronic fatigue syndrome (ISRCTN 54285094) to address these issues. In particular, autoregressive and simplex models were used to study measurement error in the mediator, different time lags in the mediator-outcome relationship, unmeasured confounding of the mediator and outcome, and the assumption of a constant mediator-outcome relationship over time. Results showed that allowing for measurement error and unmeasured confounding were important. Contemporaneous rather than lagged mediator-outcome effects were more consistent with the data, possibly due to the wide spacing of measurements. Assuming a constant mediator-outcome relationship over time increased precision. | en_US |
dc.description.sponsorship | Funding for the PACE trial was provided by the Medical Research Council, Department for Health for England, The Scottish
Chief Scientist Office, and the Department for Work and Pensions. TC, AP and KG were in part supported by the National
Institute for Health Research (NIHR) Biomedical Research Centre for Mental Health at the South London and Maudsley
NHS Foundation Trust and Institute of Psychiatry, Psychology & Neuroscience, Kings College London. KG was also funded
by an NIHR Doctoral Fellowship, DRF-2011-04-061 | en_US |
dc.format.extent | 1615 - 1633 | en_US |
dc.language | eng | en_US |
dc.relation.ispartof | Stat Methods Med Res | en_US |
dc.rights | (c) The Author(s) 2016 | |
dc.subject | Mediation | en_US |
dc.subject | chronic fatigue syndrome | en_US |
dc.subject | clinical trials | en_US |
dc.subject | longitudinal mediation models | en_US |
dc.subject | measurement error | en_US |
dc.subject | structural equation models | en_US |
dc.title | Measurement error, time lag, unmeasured confounding: Considerations for longitudinal estimation of the effect of a mediator in randomised clinical trials. | en_US |
dc.type | Article | |
dc.identifier.doi | 10.1177/0962280216666111 | en_US |
pubs.author-url | https://www.ncbi.nlm.nih.gov/pubmed/27647810 | en_US |
pubs.issue | 6 | en_US |
pubs.notes | Not known | en_US |
pubs.publication-status | Published | en_US |
pubs.volume | 27 | en_US |
qmul.funder | The PACE trial; A RCT of CBT, graded exercise, adaptive pacing and usual medical care for the chronic fatigue syndrome::Medical Research Council | en_US |