The objective was to examine consistency of adherence across depression treatments and consistency of adherence between depression treatments and treatments for chronic medical illness.

For 25,456 health plan members beginning psychotherapy for depression between 2003 and 2008, health plan records were used to examine adherence to all episodes of psychotherapy, antidepressant medication, antihypertensive medication and lipid-lowering medication.

Within treatments, adherence to psychotherapy in one episode predicted approximately 20% greater likelihood of subsequent psychotherapy adherence [odds ratio (OR)=2.20, 95% confidence interval (CI) 1.83–2.64]. Similarly, adherence to antidepressant medication in one episode predicted approximately 20% greater likelihood of subsequent antidepressant adherence (OR=1.99, 95% CI 1.74–2.28). Across treatments, adherence to antidepressant medication predicted approximately 10% greater likelihood of concurrent or subsequent adherence to psychotherapy (OR=1.52, 95% CI 1.42–1.63), a 4% greater likelihood of adherence to antihypertensive medication (OR=1.24, 95% CI 1.14–1.37) and a 3% greater likelihood of adherence to lipid-lowering medication (OR=1.16, 95% CI 1.03–1.32). Adherence to psychotherapy predicted a 2% greater likelihood of concurrent or subsequent adherence to antihypertensive medication (OR=1.11, 95% CI 1.04–1.19) and was not a significant predictor of adherence to lipid-lowering medication (OR=0.99, 95% CI 0.90–1.18).

Adherence is moderately consistent across episodes of depression treatment. Depression treatment adherence is a statistically significant, but relatively weak, predictor of adherence to antihypertensive or lipid-lowering medication.