Treating Concurrent Chronic Low Back Pain and Depression with Low-Dose Venlafaxine: An Initial Identification of "Easy-to-Use" Clinical Predictors of Early Response

Objective: Depression and chronic low back pain (CLBP) are both frequent and commonly comorbid in older adults seeking primary care. Serotonin-norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine may be effective in treating comorbid depression and CLBP. For patients with comorbid depression and CLBP, our goal was to identify "easy-to-use" early clinical variables associated with response to 6 weeks of low-dose venlafaxine pharmacotherapy that could be used to construct a clinically useful predictive model in future studies. Methods: We report data from the first 140 patients completing phase 1 of the Addressing Depression and Pain Together clinical trial. Patients aged ≥60 with concurrent depression and CLBP received 6 weeks of open-label venlafaxine 150mg/day and supportive management. Using univariate and multivariate methods, we examined a variety of clinical predictors and their association with response to both depression and CLBP; change in depression; and change in pain scores at 6 weeks. Results: About 26.4% of patients responded for both depression and pain with venlafaxine. Early improvement in pain at 2 weeks predicted improved response rates (P=0.027). Similarly, positive changes in depression and pain at 2 weeks independently predicted continued improvement at 6 weeks in depression and pain, respectively (P<0.001). Conclusions: An important minority of patients benefitted from 6 weeks of venlafaxine 150mg/day. Early improvement in depression and pain at 2 weeks may predict continued improvement at week 6. Future studies must examine whether patients who have a poor initial response may benefit from increasing the SNRI dose, switching, or augmenting with other treatments after 2 weeks of pharmacotherapy.