Correlation between pain response and improvements in patient-reported outcomes and health-related quality of life in duloxetine-treated patients with diabetic peripheral neuropathic pain

OBJECTIVE: We assessed whether quality of life (QoL) improvement in duloxetine-treated patients with diabetic peripheral neuropathic pain (DPNP) correlates with the extent of pain relief. METHODS: Pooled data from three multicountry, double-blind, 12-week, placebo-controlled trials of duloxetine-treated (duloxetine 60 mg once daily; total number =335) patients with DPNP were analyzed. Based on improvement in 24-hour average pain scores, patients were stratified into four groups. Improvement in QoL, which was measured as the change from baseline in two patient-reported health outcome measures (Short Form [SF]-36 and five-dimension version of the EuroQol Questionnaire [EQ-5D]), was evaluated and compared among the four groups. Pearson’s correlation coefficient was calculated to assess the correlation between improvement in pain scores and improvement in QoL. RESULTS: The group with more pain improvement generally showed greater mean change from baseline in all of the SF-36 scale scores and on the EQ-5D index. Pearson’s correlation coefficients ranged from 0.114 to 0.401 for the SF-36 scale scores (P<0.05), and it was 0.271 for the EQ-5D (P<0.001). CONCLUSION: Improvement in pain scores was positively correlated with improvement in QoL and patient-reported outcomes in duloxetine-treated patients.