Determinants of ethnic differences in the uptake of child healthcare services in New Zealand: a decomposition analysis

Background There are persistent ethnic gaps in uptake of child healthcare services in New Zealand (NZ), despite increasing policy to promote equitable access. We examined ethnic differences in the uptake of immunisation and primary healthcare services at different ages and quantified the contribution of relevant explanatory factors, in order to identify potential points of intervention. Methods We used data from the Growing Up in New Zealand birth cohort study, including children born between 2009 and 2010. Econometric approaches were used to explore underlying mechanisms behind ethnic differences in service uptake. Multivariable regression was used to adjust for mother, child, household, socioeconomic, mobility, and social factors. Decomposition analysis was used to assess the proportion of each ethnic gap that could be explained, as well as the main drivers behind the explained component. These analyses were repeated for four data time-points. Results Six thousand eight hundred twenty-two mothers were enrolled during the antenatal survey, and children were followed up at 9-months, 2-years and 4-years. In univariable models, there were ethnic gaps in uptake of immunisation and primary care services. After adjusting for covariates in multivariable models, compared to NZ Europeans, Asian and Pacific children had higher timeliness and completeness of immunisation at all time-points, while indigenous Māori had lower timeliness of first-year vaccines despite high intentions to immunise. Asian and Pacific mothers were less likely to have their first-choice lead maternity caregiver (LMC) than NZ Europeans mothers, and Māori and Asian mothers were less likely to be satisfied with their general practitioner (GP) at 2-years. Healthcare utilisation was strongly influenced by socio-economic, mobility and social factors including ethnic discrimination. In decomposition models comparing Māori to NZ Europeans, the strongest drivers for timely first-year immunisations and GP satisfaction (2-years) were household composition and household income. Gaps between Pacific and NZ Europeans in timely first-year immunisations and choice of maternity carer were largely unexplained by factors included in the models. Conclusions Ethnic gaps in uptake of child healthcare services vary by ethnicity, service, and time-point, and are driven by different factors. Addressing healthcare disparities will require interventions tailored to specific ethnic groups, as well as addressing underlying social determinants and structural racism. Gaps that remain unexplained by our models require further investigation.