Changes in income and movement in and out of poverty over time are only weakly associated with higher rates of child hospitalisation in New Zealand, according to a new University of Auckland study.

Published today in PLOS ONE, the collaborative study led by Dr Nichola Shackleton and Associate Professor Barry Milne from the University’s social science research centre COMPASS wanted to know if children in lower-income households ended up in hospital more frequently.

“Hospitalisation was only slightly elevated among those in poverty, and only for some conditions, notably oral health, and there was no evidence of a causal association between income poverty and hospitalisations,” says Associate Professor Milne.

New Zealand has high rates of child poverty, and poverty disproportionately affects children. Latest estimates suggest 21 percent of children live in income poverty, and 13 percent live in material deprivation (NZ Child Poverty Monitor 2020), and there is overwhelming evidence that socio-economic conditions have an impact on child health in New Zealand.

However, there is mixed evidence internationally for the impact of income poverty specifically on child health.

The study assessed income and income poverty (60 and 50 percent of the median household income, both before and after housing costs, as well as poverty persisting across years) across eight years (2002-2010) for children aged between 0 and 17 using data from the Survey of Families, Income and Employment (SoFIE) study. It also looked at poverty for children aged 0-17 from the 2013 New Zealand Census.

The study was undertaken before the development of the government’s poverty measures, so its poverty measures do not perfectly match those of the government.

These data were linked to hospitalisation records so the hospitalisations were counted for the 12-month period following the measurement of income and income poverty. They study considered ‘poverty-sensitive’ hospitalisations: otitis media (ear infections), oral health, respiratory and infection disease; as well as ‘any hospitalisation’.

However, Associate Professor Milne says the team did find associations between higher rates of hospitalisation and other measures of deprivation – material deprivation and area-level deprivation; the country is divided into ten areas from most to least deprived.

“Material deprivation is a measure that more directly tells us about families’ circumstances,” he says.

“This measure has eight indicators: receiving help from a community organisation; assistance obtaining food; wearing worn-out shoes; buying cheap food; going without fresh fruit and vegetables; feeling cold to save on heating costs; unemployment and being on a means-tested benefit.”

He says the team’s research doesn’t imply that poverty has no impact on children’s lives, or that lifting children out of poverty won’t make any difference to their lives.

“There is strong evidence that reducing poverty has beneficial impacts on education and social and behavioural development and on specific health outcomes, and this study did find associations between a different measure of poverty – material deprivation – and hospitalisation.

“However, income measures alone might not be sufficient to capture the diversity of household economic circumstances that have an impact on child health,” says Associate Professor Milne.

The research didn’t extend to investigating long-term income effects or child health issues that didn’t result in hospitalisations, which may show associations with income poverty in childhood.

The team’s next project will examine the specific role of household crowding on children’s health.

The relationship between income poverty and child hospitalisations in New Zealand: evidence from longitudinal household panel data and Census data by Shackleton N, Li E, Gibb S, Kvalsvig A, Baker M, Sporle A, Bentley R and Milne B.J.
Read the full study
The research was funded by the Health Research Council of New Zealand (grant ref HRC17-250).

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