Use of covariates in randomized controlled trials

Breukelen, Gerard van; Dijk, Koene R. A. Van

doi:10.1017/s1355617707071147

Cited by 69 publications

(39 citation statements)

References 8 publications

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“…Finally, the intensity of the previous stimulus was included as a within-subject covariate to control for intensity sequence effect which have proven to play an influence [35]. All the independent variables, except for trial (inverse), were centered (the sample mean was subtracted from each individual score) [44].…”

Section: Methodsmentioning

confidence: 99%

The Genetic Influence on the Cortical Processing of Experimental Pain and the Moderating Effect of Pain Status

et al. 2010

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BackgroundResearch suggests that the COMT Val158Met, BDNF Val66Met and OPRM1 A118G polymorphisms moderate the experience of pain. In order to obtain experimental confirmation and extension of findings, cortical processing of experimentally-induced pain was used.MethodA sample of 78 individuals with chronic low back pain complaints and 37 healthy controls underwent EEG registration. Event-Related Potentials were measured in response to electrical nociceptive stimuli and moderation by COMT Val158Met, BDNF Val66Met and OPRM1 A118G polymorphisms was assessed.ResultsGenetic variation did not have a direct effect on cortical processing of experimental pain. However, genetic effects (COMT Val158Met and BDNF Val66Met) on experimental pain were moderated by the presence of chronic pain. In the presence of chronic pain, the COMT Met allele and the BDNF Met allele augmented cortical pain processing, whilst reducing pain processing in pain-free controls. No significant effects were found concerning the OPRM1 A118G polymorphism.ConclusionsThe current study suggests that chronic experience of pain enhances genetic sensitivity to experimentally induced mildly painful stimuli, possibly through a process of epigenetic modification.

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Section: Methodsmentioning

confidence: 99%

The Genetic Influence on the Cortical Processing of Experimental Pain and the Moderating Effect of Pain Status

et al. 2010

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“…The distraction-only group (t(70)=1.88,p<.05,d=. 52) as well as the motivated-distraction group (t(70)=2.16,p<.05,d=.67) reported less pain intensity compared to the control group. There was no significant difference in reported pain intensity between the two distraction groups (t(70)=.30,ns,d=.08).…”

Section: Self-reported Pain Intensitymentioning

confidence: 95%

“…As recommended by Van Breukelen et al [52], this variable was centred. Significant main effects were further evaluated using contrast analyses.…”

Section: Data-analysismentioning

confidence: 99%

The role of motivation in distracting attention away from pain: An experimental study

Verhoeven

Crombez

Eccleston

et al. 2010

Pain

124

128

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Research on the effectiveness of distraction as a method of pain control is inconclusive. One mechanism pertains to the motivational relevance of distraction tasks. In this study the motivation to engage in a distraction task during pain was experimentally manipulated. Undergraduate students (N=73) participated in a cold pressor test (CPT) and were randomly assigned to three groups: a distraction-only group performed a tone-detection task during ther CPT, a motivated-distraction group performed the same task and received a monetary reward for good task performance, and a control group did not perform the tone-detection task. Results indicated that engagement in the distraction task was better in the motivated-distraction group in comparison with the distraction-only group. Participants in both distraction groups experienced less pain compared to the control group. There were no overall differences in pain intensity between the two distraction groups. The effect of distraction was influenced by the level of catastrophic thinking about pain. For low catastrophizers, both distraction groups reported less pain as compared to the nondistracted control group. This was not the case for high catastrophizers. For high catastrophizers it mattered whether the distraction task was motivationally relevant:High catastrophizers reported less intense pain in the motivated distraction group, as compared to the non-distracted control group. We conclude that increasing the motivational relevance of the distraction task may increase the effects of distraction, especially for those who catastrophize about pain.

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“…To assess treatment efficacy, the GET.ON Recovery and WLC groups were compared on all self-report outcome measures at T2 using univariate analyses of covariance (ANCOVA) with T1 scores as covariates to prevent bias and increase statistical power (57)(58)(59). To assess the stability of treatment efficacy, we also conducted ANCOVA with outcome scores at T3 and baseline scores (T1) as covariates.…”

Section: Treatment Efficacymentioning

confidence: 99%

Log in and breathe out: internet-based recovery training for sleepless employees with work-related strain – results of a randomized controlled trial

Thiart¹,

Lehr²,

Ebert³

et al. 2015

Scand J Work Environ Health

155

106

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Log in and breathe out: internet-based recovery training for sleepless employees with work-related strain -results of a randomized controlled trial by Thiart H, Lehr D, Ebert DD, Berking M, Riper H The present study evaluates a newly developed, internet-based recovery training that considers the particular situation of employees experiencing both work stress and sleep problems. The results suggest that this low-threshold intervention could help a large number of employees overcome a deficient recovery from work. Original article Scand J Work Environ Health. 2015;41(2):164-174. doi:10.5271/sjweh.3478 Log in and breathe out: internet-based recovery training for sleepless employees with work-related strain -results of a randomized controlled trial Objectives The primary purpose of this randomized controlled trial (RCT) was to evaluate the efficacy of a guided internet-based recovery training for employees who suffer from both work-related strain and sleep problems (GET.ON Recovery). The recovery training consisted of six lessons, employing well-established methods from cognitive behavioral therapy for insomnia (CBT-I) such as sleep restriction, stimulus control, and hygiene interventions as well as techniques targeted at reducing rumination and promoting recreational activities. AffiliationMethods In a two-arm RCT (N=128), the effects of GET.ON Recovery were compared to a waitlist-control condition (WLC) on the basis of intention-to-treat analyses. German teachers with clinical insomnia complaints (Insomnia Severity Index ≥15) and work-related rumination (Irritation Scale, cognitive irritation subscale ≥15) were included. The primary outcome measure was insomnia severity.Results Analyses of covariance (ANCOVA) revealed that, compared to the WLC, insomnia severity of the intervention group decreased significantly stronger (F=74.11, P<0.001) with a d=1.45 [95% confidence interval (95% CI) 1.06-1.84] The number needed to treat (NNT) was <2 for reliable change and NNT <4 for reduction in expert-rated diagnosis of primary insomnia. ConclusionThe training significantly reduces sleep problems and fosters mental detachment from work and recreational behavior among adult stressed employees at post-test and 6-months follow up. Given the low threshold access this training could reach out to a large group of stressed employees when results are replicated in other studies.

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Use of covariates in randomized controlled trials

Cited by 69 publications

References 8 publications

The Genetic Influence on the Cortical Processing of Experimental Pain and the Moderating Effect of Pain Status

The Genetic Influence on the Cortical Processing of Experimental Pain and the Moderating Effect of Pain Status

The role of motivation in distracting attention away from pain: An experimental study

Log in and breathe out: internet-based recovery training for sleepless employees with work-related strain – results of a randomized controlled trial

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