BackgroundThe UK Government has recently proposed the abolition of income-based measures of child poverty in favour of environmental, educational, and employment measures of deprivation. We aimed to study how strongly these proposed measures are associated with health outcomes among children and young people compared with a relative income measure. MethodsWith data from Hospital Episode Statistics for 2013–14 (n=16·4 million), we compared inequalities in inpatient admissions of children and young people aged 0–24 years per thousand (total and chronic conditions) using five deprivation measures (deciles of area-based measures: index of multiple deprivation [IMD], income, index of income deprivation affecting children [IDACI], education, living environment). With data from Health Survey for England for 2014 (n=3085), we compared inequalities in general health and long-standing illness reported by an individual, parent, or carer using equivalised household income quintiles, IMD quintiles, and whether the household reference person was employed (n=2417, 78·3%); not working (397, 12·9%); or retired, long-term sick, or other (274, 8·9%). The ratios of hospital admission rates and weighted prevalence of poor self-reported health were compared between the most and least deprived groups within each measure. FindingsTotal admission rates were higher among the most versus least deprived IMD deciles (ratio 1·60, 95% CI 1·59–1·61). The ratio was greater when income deciles were compared (1·69, 1·68–1·71) and smaller when analysis was by education (1·59, 1·58–1·60), IDACI (1·52, 1·51–1·53), and living environment (1·01, 1·00–1·02). The ratio was lower for admissions for chronic conditions (IMD 1·18, 1·16–1·20). Inequalities were largest when analysis was by income decile (1·25, 1·22–1·27). In the household-level analyses, inequalities in fair or poor, self or parent-reported health were seen when comparing lowest versus highest income quintiles (12·2% vs 3·9; ratio 3·12, 1·99–5·87), not working versus being employed (14·1 vs 6·1; 2·30, 1·68–3·03), and most versus least deprived IMD quintiles (9·8 vs 6·5; 1·49, 1·05–2·21). For long-standing illness, the equivalent data were: income (22·0 vs 11·0; 1·99, 1·50–2·77), employment (23·6 vs 15·8; 1·50, 1·21–1·81), and IMD (18·9 vs 17·2; 1·10, 0·88–1·39). InterpretationAlthough some important aspects of health such as use of primary care and community services are not included, this study shows that child poverty measures differ significantly in their association with key indicators of population health and health-care use. Of the deprivation measures studied here, hospital admissions were most strongly associated with income inequality. Self-reported health outcomes were also more strongly linked to household income than area-level IMD. FundingNone.