Firstly, this is my first time posting to this website, so I hope that I don't miss anything important. This is more of a question for advice of what to try next from people experienced with this type of analysis.
I have a moderately sized population cohort of RNA-Seq samples, ~400. As these have been processed over multiple batches and some have strong GC-bias, I chose to use salmon and tximport for processing in DESeq2. I have a number of covariates which I am interested in, as this is a control population with no sign of disease. However, from what I can understand, whilst DESeq2 will accept gender as a covariate, being a factor, it will not provide meaningful information for a continuous variable such as age. Is there a function in DESeq2 that would help to get around this, or would it be best to group ages and use a dummy variable for factoring? Or would it simply be best to use limma-voom for this purpose.