Is the self-reported private health insurance status in the National Health Survey representative of private health insurance coverage in Australia?

OBJECTIVE

This study determines whether the distribution of self-reported private health insurance (PHI) status in the 2004/05 National Health Survey (NHS) is representative of PHI coverage in Australia.

METHODS

Weighted estimates from the NHS 2004/05 are compared with PHI status reported for 2004/05 by the Private Health Insurance Administration Council (PHIAC, the independent regulator of the private health insurance industry). PHI status was imputed to children in the NHS based on PHI status of the adult in the household. The two data sources were deemed to be different if the PHIAC results were not within the 95% CI range for the NHS estimate.

RESULTS

PHI status reported in the NHS and PHIAC are generally comparable except for some categories such as hospital cover of males aged 5-9 years and females aged 85 years and older where the NHS estimates are below PHIAC numbers; and males aged 25-29, 35-39, and 50-54 years where the NHS estimates are higher.

CONCLUSIONS

The findings suggest that while the NHS 2004/05 estimates may accurately represent coverage in Australia particularly when examined at an aggregated level, there is some variation in the NHS estimates when examined by sex and age group.

IMPLICATIONS

Researchers need to be aware of the potential for sampling and reporting bias to contribute to some misrepresentation of PHI status when using the NHS to generalise to the Australian population. Exploring corrective measures will ensure that the NHS continues to be a valuable data resource for health researchers in Australia.