Evaluation of Duloxetine Effectiveness in the Management of DPNP with Respect to Baseline Characteristics

Objective

To examine impact of age, gender, origin, duration of diabetic neuropathy, type of diabetes, and pain severity on treatment outcome of duloxetine (DLX) in the management of diabetic peripheral neuropathic pain (DPNP).

Methods

Data from 3 12-week, multicenter, double-blind, placebo-controlled studies (1-3) were pooled. In Study 1, 457 patients with DPNP were randomly assigned to DLX 20 mg QD, 60 mg QD, 60 mg BID, or placebo. In Studies 2 and 3, 334 and 348 patients, respectively, were randomly assigned to DLX 60 mg QD, 60 mg BID, or placebo. DLX 20 mg QD was not included in the analyses due to its ineffectiveness found in Study 1. Primary efficacy measure was the weekly mean score of 24-Hour Average Pain Severity collected by patient’s diary on 11-point Likert scale. Subgroup impact was evaluated for combined DLX doses with references to placebo group.

Results

DLX 60 mg QD and 60 mg BID significantly improved weekly mean scores of 24-Hour Average Pain Severity in each study (p < 0.001). There were no statistical significant (p < 0.1) interactions of treatment with age (<65 or ≥65), gender (male or female), origin (Caucasian or other), duration of diabetic neuropathy (<2, 2–<6, or ≥6 years), type of diabetes (Type I or Type II) with an exception for pain severity (BPI average pain <6 or ≥6). DLX effect was observed for both severe and less severe groups with more separation on the severe group. The superiority of DLX over placebo was observed within almost each of the stratum with the exception of Type I patient group, which demonstrated the advantage of DLX treatment with p = 0.123. The magnitude of change was slightly higher in Type II patients than in those with Type I; however, Type I group sample size was much smaller which may account for the statistical insignificance. DLX was safe and well tolerated with less than 20% discontinuation due to AEs, while showing no interference with diabetic control.

Conclusion

These studies suggested that DLX was effective and safe in the treatment of DPNP, and its effectiveness was invariant with respect to baseline conditions.

Funding provided by Eli Lilly and Company.