Hello, I would like to seek some advice on incidence rate calculation (person-years) for a surveillance study.

I'm calculating incidence rate (with CIs) and my data set in Stata (16MP) so far only includes those cases we have recorded with disease. All children in the cohort are at risk (at least until they develop the disease) and there is no exposure variable. They include some x33 cases, and I've started by calculating the survival time for these cases (in days).

The problem I've got is creating in Stata the correct denominator, as we are aiming to calculate incidence of disease across the 5-15yr old population in UK and RoI. As this is a surveillance study I am effectively exploring a population size of 10,355,298 children but these are not represented anywhere in my data set. I'm not sampling the population, as this is a surveillance study and we are aiming to catch every incident case.

I can't find a way for Stata to allow me to input this figure in anywhere. I can't realistically create data entries for 10 million non-diseased children, and if I could I don't think Stata would like it. The page: https://www.stata.com/features/table...idemiologists/ is of limited use for my calculation.

Could I have some advice please? I realise using Stata for this application might seem overkill for a straight-forward calculation but I would use it to obtain the CIs.

Many thanks in advance.

Sandy