Evaluating the impact of prescriptive authority for psychologists on the rate of deaths attributed to mental illness

Five states have enacted policies granting prescriptive authority to psychologists in an effort to increase access to psychoactive medications; however, little is known regarding the public health impact of these policies. Policies in two of these states, New Mexico and Louisiana, have had sufficient time to license more than a handful of prescribing psychologists. This study estimates the impact of psychologist prescriptive authority policies in New Mexico and Louisiana on deaths attributable to mental illness and suicides.

State-level annual death rates from all 50 states were obtained for deaths with an underlying cause of death attributable to mental illness and to suicide (1999-2013) from the Centers for Disease Control and Prevention's WONDER database. State characteristics were collected for the pre-policy time period (1999-2004). We estimated the impact of the policy on the rates of deaths attributable to mental illness and to suicide using a comparative interrupted time series design, and policy effect estimates were generated for New Mexico and Louisiana separately. We used the synthetic control method to create synthetic New Mexico and synthetic Louisiana for use as the comparators.

Immediately following the start of psychologist prescribing, the rate of deaths attributable to mental illness declined by 4.55 deaths per 100,000 (95% CI: [-8.30, -0.79]) in New Mexico relative to the control, but there was no change in Louisiana. There was no immediate change in the suicide rate in either state; however, the annual change in the overall suicide rate was 0.12 suicides per 100,000 (95% CI: [-0.18, -0.06]) per year lower than expected in Louisiana following implementation.

These findings suggest that policies granting prescriptive authority to psychologists have the potential to reduce the mental health mortality gap, though considerable questions remain.