Constructing comprehensive population cohorts for health and social research using the New Zealand Integrated Data Infrastructure (IDI)

Abstract

Having an appropriate population denominator is crucial for analysing health and social data. However, the most common sources of population denominators in New Zealand have their limitations. In this presentation, we outline the construction of the “VIEW-IDI cohort” - the largest and most comprehensive individual level population cohort possible for census day 2013 using Statistics NZ’s Integrated Data Infrastructure (IDI) for use as a denominator in health and social research. We also used the IDI to construct two commonly used population denominators for census day 2013: a Health Service Utilisation (HSU) population using health datasets alone, and the usually-resident population who completed the 2013 population Census. We compared the three cohorts by age, gender, ethnicity, area deprivation (NZDep2013) and District Health Board. Separate cardiovascular disease (CVD) prevalence estimates were calculated for the three population denominators, which were compared by age, gender and ethnicity to determine the extent to which the CVD prevalence was over- or under-estimated in the HSU and Census populations, using the IDI population as standard. The IDI environment offers significant opportunities for health and social research. The VIEW-IDI population denominator was designed to extend our research on developing CVD-risk prediction tools using routine data, however the methodology created a national cohort that can be used to explore social, demographic and geographic variations for any health outcome.