Social determinants of health among culturally and linguistically diverse people in Australia

For people who migrated to Australia, the proportion with any of the long-term health conditions increased over time from when they first arrived in Australia. 

Modelling the odds of selected long-term health conditions from time spent in Australia since first arrival

This section presents the results of logistic regression modelling the odds of each long-term health condition based on the length of time since first arriving in Australia. In these models, people who first arrived in Australia 0 to 10 years previously (before the 2021 Census) were used as the reference category, when estimating the odds ratios. Full output from all regression models is provided in the supplementary tables (Tables S2.1–S2.4).  

The overall results observed from all regression models indicate that age had the largest effect on the odds of most reported long-term health conditions, with the exception of asthma and mental health conditions. Further data are needed to identify the social and economic drivers behind the observed associations between time spent in Australia since first arrival and reported long-term health conditions. Detailed findings from the modelling are presented below.

1. Unadjusted models

The odds ratios observed in the unadjusted models showed that a longer time spent in Australia since first arrival was associated with higher odds of reporting long-term health conditions. People who first arrived in Australia more than 10 years ago (i.e. 11 to 20 years ago or more than 20 years ago) had higher odds of reporting all long-term health conditions, compared with those who arrived 0 to 10 years ago. For both males and females, the odds ratios for:

• asthma and mental health conditions were highest for those born in Australia
• all reported long-term health conditions other than asthma were highest for those who arrived in Australia more than 20 years ago.

2. Adjusting separately for age and social determinants of health

When the results were separately adjusted for age and the social determinants of health, controlling for age substantially changed the odds ratios for the reported long-term health conditions other than asthma and mental health conditions. The effect of adjusting for age alone on the odds ratios was strongest for those who arrived in Australia more than 20 years ago. However, the effect of adjusting for other social determinants of health on the odds ratios showed a smaller, but still statistically significant effect. Adjusting for labour force (or occupation), marital status, housing tenure or income were all significant, particularly for people who arrived in Australia more than 20 years ago. For example, the unadjusted odds ratios for reporting heart disease were 10.0 for males and 8.1 for females who arrived in Australia more than 20 years ago compared with males and females who arrived in Australia 0 to 10 years earlier. These odds ratios dropped to:

• 1.4 for males and 1.3 for females after adjusting only for age
• 6.8 for males and 5.9 for females after adjusting only for labour force status
• 6.4 for males and 5.5 for females after adjusting only for housing tenure
• 7.1 for males and 4.9 for females after adjusting only for marital status.

This pattern was similar when considering some other reported multimorbidity, arthritis, diabetes, or heart disease.

3. Fully adjusted models

In the fully adjusted models, for both males and females, the odds ratios for reporting the long-term health conditions associated with time since arrived in Australia generally remained similar to the corresponding age adjusted odds ratios. For example, when unadjusted, the odds of males who arrived in Australia more than 20 years ago reporting multimorbidity was 12.4 higher than that of males who arrived in Australia 0 to 10 years ago. This odds ratio dropped to 3.0 when only the effect of age was taken into account. The odds ratio was 3.3 in the fully adjusted model, that is, when the results were adjusted for the effects of age, education, labour force status, income, housing suitability, tenure, citizenship status, remoteness and marital status (Table 2 below). 

The odds ratios for the reported long-term health conditions increased as time spent in Australia since first arrival increased and was generally highest for those born in Australia, with some exceptions. For example, among males, the highest odds ratio for reported diabetes was observed in those who first arrived in Australia 11 to 20 years ago (1.2), followed by those who arrived more than 20 years ago (1.1) and was lower among those born in Australia (0.9). 

Notes

1. Results are from the fully-adjusted model which included Time spent in Australia, age, education, income, employment, tenure, housing suitability, remoteness, citizenship, marital status and occupation. Analysis excluded overseas visitors, people who live in non-private dwellings or Migratory, offshore and shipping SA1s, non-classifiable households or Visitor only households. 
2. Analyses included 7,751,459 males and 8,065,784 females aged 15 and over living in Australia in occupied private dwellings on Census Night, who were not overseas visitors and provided a valid response to the 2021 Census questions on year of arrival in Australia, age, the selected social determinants of health, and the long-term health conditions. 
3. The '0 to 10 years' category was selected as the reference category, when calculating the odds ratios for the levels of time spent in Australia since first arrival.  
4. OR (95% CI) refers to odds ratio and the 95% confidence interval.
5. All odds ratios are rounded to two decimal places.

Source: AIHW analysis of PLIDA, 2021.