OBJECTIVE: Clinicians observe great variability in MBB effectiveness. Few predictors for success have been identified, except for age, work status, and bone scan findings. Psychopathology (primarily depression and anxiety) is highly prevalent in patients with chronic musculoskeletal pain, and is a significant predictor of treatment response. Its impact on MBB efficacy is unknown, and we hypothesized that psychopathology was associated with diminished effectiveness.

METHODS: With IRB approval, this was a prospective cohort study of 86 consecutive patients (cervical or lumbar pain) treated with a MBB (bupivacaine + methylprednisolone). Each patient had predominately axial pain and either CT or MRI findings of facet hypertrophy (controversial but common selection criteria). At baseline they completed the Brief Pain Inventory and the Hospital Anxiety and Depression Scale, which was repeated at one month follow up. The primary predictor was the degree of psychopathology, determined by validated cutoff scores of depression and anxiety symptoms (Low, Moderate, High). Percent improvement in average daily pain rating was the primary outcome.

RESULTS: N=86 (Low group=42, Moderate=13, and High=31). No significant differences between groups found in duration of pain, baseline pain, average age, and percent with previous spine surgery (7 years, 6.3/10, 60 years, 36.4%). At one month, ANOVA revealed that the Low group had 19.4% improvement in pain, Moderate 11.3%, and the High group –5.6% (p<.01). An ANCOVA examined secondary predictors of pain improvement, none of which were significant (gender, location of pain, work status, workers compensation, opioid use, and other concurrent treatments). All three groups rated similar improvements in the secondary outcomes of quality of life measures (activity, walking, work, sleep), average 7.2% improvement.

CONCLUSIONS: Psychiatric comorbidity negatively impacts MBB effectiveness. But all three groups had similar, yet minor improvements in quality of life at one month. These findings help to explain the variability in treatment response.