Improving access to mental health care: a system dynamics model of direct access to specialist care and accelerated specialist service capacity growth.

objectiveTo simulate the impact on population mental health indicators of allowing people to book some Medicare-subsidised sessions with psychologists and other mental health care professionals without a referral (direct access), and of increasing the annual growth rate in specialist mental health care capacity (consultations).

designSystem dynamics model, calibrated using historical time series data from the Australian Bureau of Statistics, HealthStats NSW, the Australian Institute of Health and Welfare, and the Australian Early Development Census. Parameter values that could not be derived from these sources were estimated by constrained optimisation.

settingNew South Wales, 1 September 2021 - 1 September 2028.

main outcome measuresProjected mental health-related emergency department presentations, hospitalisations following self-harm, and deaths by suicide, both overall and for people aged 15-24 years.

resultsDirect access (for 10-50% of people requiring specialist mental health care) would lead to increases in the numbers of mental health-related emergency department presentations (0.33-1.68% of baseline), hospitalisations with self-harm (0.16-0.77%), and deaths by suicide (0.19-0.90%), as waiting times for consultations would increase, leading to disengagement and consequently to increases in adverse outcomes. Increasing the annual rate of growth of mental health service capacity (two- to fivefold) would reduce the frequency of all three outcomes; combining direct access to a proportion of services with increased growth in capacity achieved substantially greater gains than an increase in service capacity alone. A fivefold increase in the annual service growth rate would increase capacity by 71.6% by the end of 2028, compared with current projections; combined with direct access to 50% of mental health consultations, 26 616 emergency department presentations (3.6%), 1199 hospitalisations following self-harm (1.9%), and 158 deaths by suicide (2.1%) could be averted.

conclusionThe optimal combination of increased service capacity growth (fivefold) and direct access (50% of consultations) would have double the impact over seven years of accelerated capacity growth alone. Our model highlights the risks of implementing individual reforms without knowledge of their overall system effect.