Relationship between pain relief and improvements in patient function/quality of life in patients with painful diabetic peripheral neuropathy or postherpetic neuralgia treated with pregabalin

Clin Ther. 2013 May;35(5):612-23. doi: 10.1016/j.clinthera.2013.03.008. Epub 2013 Mar 28.

Abstract

Background: In patients with chronic pain due to diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN), pregabalin treatment results in pain relief and improved patient function/quality of life (QoL). Few studies, however, have examined the exact relationship between pain relief and improvements in patient function/QoL. It is unclear, for example, whether pregabalin has a direct independent effect on patient function/QoL or whether improvements in function/QoL are an indirect consequent of pain relief.

Objectives: To determine whether improvements in function/QoL in response to pregabalin treatment are related to the extent of pain relief in patients with neuropathic pain due to DPN or PHN and to determine whether pregabalin has a direct independent effect on patient function/QoL that is distinct from its effects on pain.

Methods: Data from 11 randomized, double-blind, placebo-controlled trials of pregabalin for the treatment of DPN or PHN were pooled for this analysis. Changes in patient function/QoL scores were plotted according to the extent of pain relief to assess whether greater levels of pain relief were associated with greater improvement in function/QoL. A novel mediation analysis was used to asses to what extent the effects of pregabalin on function/QoL scores are a direct treatment effect as opposed to an indirect effect mediated through improvements in pain or sleep.

Results: Moderate-to-substantial pain relief (a ≥30% decrease in pain) in response to pregabalin treatment was associated with significant (P < 0.05) improvements in 36-Item Short Form Health Survey (SF-36) scores (used to assess patient function/QoL). In many patients, greatest improvement in SF-36 scores was reported by patients achieving ≥50% decrease in pain. Analysis of Patient Global Impression of Change scores revealed a similar trend, where >80% of patients who achieved substantial pain relief also reported their status as much or very much improved. A substantial direct pregabalin treatment effect was evident for many SF-36 domains that could not be explained by pain relief or improvement in sleep.

Conclusions: In patients with chronic pain due to DPN or PHN, improvements in patient function/QoL in response to pregabalin treatment are correlated with the extent of pain relief. However, such improvements in function/QoL are not mediated entirely through pain relief but are the result of a combination of pregabalin's effects on pain and sleep disturbance and a direct effect on patient function itself.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics / therapeutic use
  • Diabetic Neuropathies / drug therapy*
  • Diabetic Neuropathies / physiopathology
  • Health Surveys
  • Humans
  • Neuralgia, Postherpetic / drug therapy*
  • Neuralgia, Postherpetic / physiopathology
  • Pregabalin
  • Quality of Life
  • Randomized Controlled Trials as Topic
  • Sleep Wake Disorders / drug therapy
  • Sleep Wake Disorders / etiology
  • Treatment Outcome
  • gamma-Aminobutyric Acid / analogs & derivatives*
  • gamma-Aminobutyric Acid / therapeutic use

Substances

  • Analgesics
  • Pregabalin
  • gamma-Aminobutyric Acid