[R] Regression and Sub-Groups Analysis in Metafor

[Dan Kolubinski]

I am completing a meta-analysis on the effect of CBT on low self-esteem and
I could use some help regarding the regression feature in metafor.  Based
on the studies that I am using for the analysis, I identified 4 potential
moderators that I want to explore:
- Some of the studies that I am using used RCTs to compare an intervention
with a waitlist and others used the pre-score as the control in a
single-group design.
- Some of the groups took place in one day and others took several weeks.
- There are three discernible interventions being represented
- The initial level of self-esteem varies

Based on the above, I used this command to conduct a meta-analysis using
standarized mean differences:



MetaMod<-rma(m1i=m1, m2i=m2, sd1i=sd1, sd2i=sd2, n1i=n1, n2i=n2,
mods=cbind(dur, rct, int, level),measure = "SMD")



Would this be the best command to use for what I described?  Also, what
could I add to the command so that the forest plot shows a sub-group
analysis using the 'dur' variable as a between-groups distinction?


Also, with respect to the moderators, this is what was delivered:



Test of Moderators (coefficient(s) 2,3,4,5):
QM(df = 4) = 8.7815, p-val = 0.0668

Model Results:

         estimate      se     zval    pval    ci.lb   ci.ub
intrcpt    0.7005  0.6251   1.1207  0.2624  -0.5246  1.9256
dur        0.5364  0.2411   2.2249  0.0261   0.0639  1.0090  *
rct       -0.3714  0.1951  -1.9035  0.0570  -0.7537  0.0110  .
int        0.0730  0.1102   0.6628  0.5075  -0.1430  0.2890
level     -0.2819  0.2139  -1.3180  0.1875  -0.7010  0.1373

---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1



>From this, can I interpret that the variable 'dur' (duration of
intervention) has a significant effect and the variable 'rct' (whether a
study was an RCT or used pre-post scores) was just shy of being
statistically significant?  I mainly ask, because the QM-score has a
p-value of 0.0668, which I thought would mean that none of the moderators
would be significant.  Would I be better off just listing one or two
moderators instead of four?

Much appreciated,
Dan

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