In two of the fruit and vegetable intervention trials with follow-up of participants at one year and again at two years, the mean intervention effect on fruit and vegetable intake measured at the end of the intervention (i.e. at one year) had decreased by 62% [29] and 50% [30] by the end of the subsequent year.
However, the mean intervention effect amounted to only +1.33 points (95% CI [−4.33; 6.98], p = 0.645) and was not significant.
32 The mean intervention effect for this measure (after adjustment for baseline measurement and minimisation stratifiers) was not significant at 12 month follow-up (−0.04 (95% confidence interval −0.16 to 0.08)).
The findings of this study may therefore reflect a regression to the mean rather than intervention effects.
See supplementary table, additional file 1. Publication bias was assessed using funnel plots with standard error as the vertical axis and standard mean difference for intervention effects on the horizontal axis [ 45].
Both GEE and GLMM use repeated outcome measures and take the intra-personal association into account, and provide a means to comparing intervention effects at each time point and to examining whether the effects vary over time [ 2].
95% CI not crossing 1 were considered statistically significant, as determined by single sample t-tests on the mean perfusion ratios with a population mean of 1. Intervention effects on regional microvasculature morphology measures were assessed using paired t-tests.
The marginally significant effect favouring the intervention in Bakitas 2009 (mean treatment effect 27.8, standard error (SE) = 15; P value = 0.06; Edmonton Symptom Assessment Scale; nine symptoms; 0 to 900 scale, 900 = worst) was detected in the 13 months following enrolment through repeated measures analysis.
We estimated intervention effects as standardised mean differences the difference in mean outcome between groups divided by a pooled standard deviation within groups.
Since positive and negative mean centroid values suggest higher and lower gene expression in all analyzed genes in the pathway, respectively, the following main findings for sex and intervention effects, considering mean centroid values > + 0.01 and < − 0.01, were obtained.
