I am developing network meta-analysis BUGS model that I will use to compare Hazard Ratios in studies that assume Box Proportional Hazard model.
As input I am given pairs: (log HR, its standard error) that measure magnitude of the effect of difference between two treatments. Naturally I assume normal distribution model for the log HR ("LHR" for short) with its given SE.
Problem is, when I have more than one LHR result from a single study: sometimes these results are based on independent groups - and then I treat them just as if they came from separate studies.
But more often than not these results are based on multiple comparisons in more than two-arms experiment on the same group. It means, that they have e.g. 4 groups of patients: A, B, C and d and report Hazard Ratios A vs B, A vs C, A vd D, B vs C, B vs D and C vs D. These 6 results are not-so-independent, so I can't really treat them as independent in my BUGS model.
So I believe that treating them as separate studies is wrong, but what else can I do?
If that is relevant for you, I can post actual BUGS model.