Socioeconomic disparities in the association between macroeconomic changes and suicide: a population-level time series study in Australia.

Background: In the current cost-of-living crisis, there is concern that sharp rises in annual inflation and the benchmark interest rate may increase suicide, particularly for vulnerable groups. We aimed to examine the association between relevant macroeconomic changes and suicide across the socioeconomic spectrum to inform policy responses. Methods: In this population-level time series study, we obtained monthly suicide counts, annual inflation, and the cash rate from January 2006 to October 2023 for Australia. We also obtained related indictors, quarterly household saving to income ratio and owner-occupier housing debt to income ratio, for the same period. We conducted Poisson regression analysis at the monthly/quarterly level to examine the associations between these macroeconomic indicators (lagged by one month/quarter) and suicide for all persons and by five socioeconomic groups (Quintile 1 being the most disadvantaged to Quintile 5 being the least disadvantaged). Findings: In Australia, every 1% monthly increase in annual inflation was associated with a 4% increase in suicide rate one month later in the general population [Incidence Rate Ratio (IRR) 1.04, 95% Confidence Interval (CI) 1.01‒1.06, p = 0.011]. The increase was greater (7%) for people residing in the most and the least disadvantaged areas. For the latter group, such increase persisted three months later. A 1% quarterly increase in household saving to income ratio was associated with a 1% increase in suicide rate one quarter later among people residing in the least disadvantaged areas (Quintile 5: IRR 1.01, 95% CI 1.00-1.02, p = 0.019). A 1% quarterly increase in housing debt to income ratio was associated with a 6% increase in suicide rate in the same quarter among people residing in less disadvantaged areas (Quintile 4: IRR 1.06, 95% CI 1.02-1.10, p = 0.004). In contrast, opposite associations were observed for the one-quarter-lagged housing debt to income ratio for people residing in more disadvantaged areas (Quintile 2: IRR 0.97, 95% CI 0.93-1.00, p = 0.047) and the one-month-lagged cash rate for people residing in moderately disadvantaged areas (Quintile 3: IRR 0.88, 95% CI 0.78-0.99, p = 0.030). Interpretation: Our study provides first evidence that the association between macroeconomic changes and suicide varied based on socioeconomic disadvantage. This underscores the need for policies to consider the differential effect to alleviate financial strain to prevent suicide. Funding: The Australian Government Department of Health, Disability and Ageing.