If early results from a trial were published after one year of follow-up and then a second paper with longer follow-up was published a few years later, is it appropriate to include both of these...

If early results from a trial were published after one year of follow-up and then a second paper with longer follow-up was published a few years later, is it appropriate to include both of these publications in a systematic review or meta-analysis of the topic? Why/why not?