Socioeconomic differences in antidepressant use in the PATH Through Life Study: evidence of health inequalities, prescribing bias, or an effective social safety net?

Background: Depression is more common amongst those who are economically disadvantaged. However there is inconsistent evidence concerning the relationship between socioeconomic position and antidepressant use. Moreover, evidence of greater antidepressant use amongst those of lower socioeconomic position may reflect their greater psychiatric morbidity, a prescribing bias towards pharmacological treatments, or provide evidence of an effective social safety net. This study investigates these issues whilst addressing methodological limitations of earlier studies.

Method: Data were from a large, random community survey of Australian adults (N=4493) with linked administrative data for primary-care service use. Depression was measured using the Patient Health Questionnaire, with other measures of current mental health and history of depression included in analysis. Multiple personal indicators and a combined measure of social disadvantage were considered. A series of analyses systematically examined competing explanations for socioeconomic differences in depression and antidepressant treatment.

Results: Markers of socioeconomic disadvantage were associated with a greater likelihood of antidepressant use. This finding was not attributable to the higher rates of depression amongst the disadvantaged. A similar pattern of results was evident for non-pharmaceutical treatments (primary care consultations). Socioeconomic position was not associated with use of complementary medications for depression, not covered by Australia's social safety net.

Limitations: Analysis did not consider specialist mental health services.

Conclusions: Socially disadvantaged respondents reported greater antidepressant use and service use after controlling for current depression symptoms. This pattern of findings suggests Australia's universal health-care system and social safety net may help address potential inequalities in health care.