Objectives: This study aimed to examine the differences in multimorbidity between Aboriginal and Torres Strait Islander people and non-Indigenous Australians, and the effect of multimorbidity on health service use and work productivity.

Setting: Cross-sectional sample of the Household, Income, and Labour Dynamics in Australia Wave 17.

Participants: A nationally representative sample of 16,749 respondents aged 18 years and above.

Outcome measures: Multimorbidity prevalence and pattern, self-reported health, health service use, and employment productivity by Indigenous status.

Results: Aboriginal respondents reported a higher prevalence of multimorbidity (24.2%,) compared to non-Indigenous Australians (20.7%), and the prevalence of mental-physical multimorbidity was almost twice as high (16.1% vs 8.1%). Multimorbidity pattern varies significantly among the Aboriginal and non-indigenous Australians. Multimorbidity was associated with higher health service use (any overnight admission: AOR=1.52, 95% CI = 1.46 to 1.58), reduced employment productivity (days sick leave: coef.=0.25, 95% CI = 0.19 to 0.31), and lower perceived health status (SF6D score: coef.=-0.04, 95% CI = -0.05 to -0.04). These associations were found to be comparable in both Aboriginal and non-Indigenous populations.

Conclusions: Multimorbidity prevalence was significantly greater among Aboriginal and Torres Strait Islanders compared to the non-Indigenous population, especially mental-physical multimorbidity. Strategies are required for better prevention and management of multimorbidity for the aboriginal population to reduce health inequalities in Australia.