Objective: To examine the impact of depression on adherence to disease-modifying therapy (DMT) for MS.
Methods: A retrospective database was used to identify MS'ers treated with a DMT. Adherence to DMT was proxied by the medication possession ratio (MPR); an index of how often the medication is taken (calculated on frequency of filling precriptions).
Results: MS'ers with depression had a 10 point lower MPR (P < 0.01) and were less likely to achieve a MPR of at least 80% (odds ratio (OR) = 0.55; 95% confidence interval (CI) 0.42-0.74) than those without depression. While treatment with an antidepressant generally had no significant impact on the likelihood of achieving an MPR threshold of 80% (OR = 1.32; 95% CI 0.50-3.48), adherence to antidepressant therapy guidelines were associated with improved adherence to DMT therapy.
Conclusions: MS patients with comorbid depression were approximately half as likely to be adherent to their DMT relative to patients with MS without depression. Although treatment with antidepressant therapy generally did not improve the likelihood of adherence, treatment with antidepressants for at least 6 months was associated with better adherence to DMT.
"These results are not surprising and a reminder to us to treat MS holistically. If you don't manage the depression you won't control the disease."