I have a question regarding pooling hazard ratios derived through different means for a meta-analysis. Software: RevMan 5; Method: generic inverse variance (log hazard ratios).
My issue is that some studies calculate hazard ratio while treating the parameter as a continuous variable (e.g.: HR of 1.3, which means risk is increased by 1.3x per unit increase in SUVmax). However, some studies calculate the hazard ratio while treating SUVmax as a dichotomous variable by using a cut-off (e.g.: cut-off of 5; HR is 4.0, which means SUVmax > 5 is four times riskier compared to SUVmax < 5)
Is it safe to simply pool these hazard ratios together as they are (continuous and dichotomous) for meta-analysis? It does not seem statically sound to me, but 3 other published meta-analyses that I've found on PET-parameters pooled continuous and dichotomous HRs together so I don't know who's right or wrong.