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.