I have summary data for 2 years of information regarding the number of blood transfusions given to a group of preterm babies

Year Blood transfusions Pt days Transfusions/1000 pt days

1 293 6032 39.11

2 251 4987 33.52

Some babies received several transfusions whilst others received none. I have calculated there ratios and 95% CI for these ratios BUT is there a more robust way of determing if the rates (transfusion/1000 pt days) is different?

Many Thanks!!!!