Validation of the Dutch version of the DN4 diagnostic questionnaire for neuropathic pain.

Difficulties in diagnosing neuropathic pain in routine clinical practice support the need for validated and easy-to-use diagnostic tools. The DN4 neuropathic pain diagnostic questionnaire aims to discriminate neuropathic pain from nociceptive pain, but needs clinical validation. A total of 269 patients with chronic pain in three pain clinics were included in the study of which 248 had analyzable data. The mean duration of pain was 4.9 years. The most frequent etiologies were posttraumatic (36%), (pseudo) radicular (14%), and mechanical back pain (12%). The mean intensity of pain at visit was 5.6 on a 0-10 scale. Hundred and ninety-six of 248 patients had an identical pain diagnosis from both physicians: 85 had neuropathic pain, 57 had nociceptive pain, and 54 had mixed pain. Among patients with identical diagnoses of neuropathic or nociceptive pain, using a receiver operating characteristic curve analysis, the area under the curve (AUC) was 0.81 for the DN4 7-item and 0.82 for the 10-item version. A cutoff point of 5/10 for the full questionnaire resulted in a sensitivity of 75% and a specificity of 79%, while a cutoff point of 4/7 for the partial questionnaire resulted in a sensitivity of 74% and a specificity of 79%. The items "brushing," "painful cold," and "numbness" were most discriminating. The DN4 is an easy-to-use screening tool that is reliable for discriminating between neuropathic and nociceptive pain conditions in daily practice. Item-specific scores provide important information in addition to the total score.

Relationships between changes in pain severity and other patient-reported outcomes: an analysis in patients with posttraumatic peripheral neuropathic pain.

BACKGROUND: The objective of this study is to use the pain numeric rating scale (NRS) to evaluate associations between change in pain severity and changes in sleep, function, and mood assessed via patient-reported outcomes (PROs) in patients with posttraumatic pain. METHODS: This is a secondary analysis of a clinical trial evaluating pregabalin in patients with posttraumatic peripheral neuropathic pain (N = 254). Regression models were used to determine associations between changes in pain (0-10 NRS) as the predictor and scores on the following PRO measures as the outcome: Pain Interference Index; Hospital Anxiety and Depression Scale anxiety and depression subscales; Medical Outcomes Study-Sleep Scale 9-item Sleep Problems Index and Sleep Disturbance subscale; and Daily Sleep Interference Scale (0-10 NRS). RESULTS: Change in pain severity showed clear, direct relationships with changes in function, anxiety, depression, and sleep PROs, all of which were statistically significant (P <.001). Results from subgroup analyses (≥30% or ≥50% pain responders, pregabalin or placebo treatment, age ≤ 51 years or > 51 years) tended to be consistent with results from the overall sample. CONCLUSIONS: Overall, a direct relationship exists between pain and various aspects of patient's well-being and functioning, which can provide a quantitative assessment of how improvements in pain may be expected to relate to other patient outcomes. (http://ClinicalTrials.gov Identifier number NCT00292188; EudraCT #2005-003048-78).

The effect of pregabalin on pain-related sleep interference in diabetic peripheral neuropathy or postherpetic neuralgia: a review of nine clinical trials.

OBJECTIVE: Postherpetic neuralgia and painful diabetic peripheral neuropathy are common chronic neuropathic pain conditions associated with sleep disturbances. Pregabalin is indicated in the treatment of neuropathic pain. The objective of this review is to summarize the efficacy and safety of pregabalin in painful diabetic peripheral neuropathy and postherpetic neuralgia and the effect of pregabalin on sleep interference in these patients. METHODS: MEDLINE and ISI Web of Knowledge databases were searched for randomized double-blind, placebo-controlled clinical trials of pregabalin reporting sleep measures in addition to pain endpoints in patients with painful diabetic peripheral neuropathy and postherpetic neuralgia published from inception through March 2009. RESULTS: Nine trials met the inclusion criteria, providing data for a total of 2399 patients with painful diabetic peripheral neuropathy or postherpetic neuralgia treated twice or three times per day with pregabalin (75-600 mg/day) or placebo on a fixed or flexible schedule. Interpretation of sleep outcomes in two studies may be limited by trial inclusion criteria which permitted benzodiazepines for sleep problems. Also, none of the studies reported objective sleep measures. Pregabalin was well tolerated. Pregabalin (150-600 mg/day) significantly reduced pain and improved pain-related sleep interference. CONCLUSIONS: In addition to an analgesic benefit, pregabalin may decrease pain-related sleep interference in patients with painful diabetic peripheral neuropathy and postherpetic neuralgia.

Continuous positive airway pressure breathing increases cranial spread of sensory blockade after cervicothoracic epidural injection of lidocaine.

BACKGROUND: Continuous positive airway pressure (CPAP) increases the caudad spread of sensory blockade after low-thoracic epidural injection of lidocaine. We hypothesized that CPAP would increase cephalad spread of blockade after cervicothoracic epidural injection. METHODS: Twenty patients with an epidural catheter at the C6-7 or C7-T1 interspace received an epidural dose of lidocaine while breathing at ambient pressure (control group), or while breathing with 7.5 cm H2O CPAP. After injection, we evaluated the spread of sensory blockade. Spirometry variables before and after epidural injection were also measured. RESULTS: Data are presented as median (interquartile range) values. Sensory block ranged from C7 (C4-7) to T4 (T4-6) in the control group and from C2 (C2-4) to T4 (T2-5) in the CPAP group (P = 0.003 for the cranial border). The total number of segments blocked was 7.5 (6.8-9.8) in the control group and 10 (8-12) in the CPAP group (P = 0.13). The number of segments blocked cranial to the injection site was one (0.8-3.5) in the control group and five (3.5-7) in the CPAP group (P = 0.006). The number of patients with a maximal cranial block (up to C2) was one in the control group and seven in the CPAP group (P = 0.02). In both groups, there was a small but significant decrease from baseline in spirometry values, with no differences between groups. CONCLUSION: Applying CPAP during cervicothoracic epidural injection of lidocaine resulted in a more cranial extension of sensory blockade when compared with breathing at ambient pressure.

Efficacy and tolerability of twice-daily pregabalin for treating pain and related sleep interference in postherpetic neuralgia: a 13-week, randomized trial.

OBJECTIVE: This trial evaluated the efficacy and safety of pregabalin dosed twice daily (BID) for relief of neuro-pathic pain associated with postherpetic neuralgia (PHN). RESEARCH DESIGN AND METHODS: The 13-week, double-blind, placebo-controlled study randomized 370 patients with PHN to pregabalin (150, 300, or 600 mg/day BID) or placebo. MAIN OUTCOME MEASURES: Primary efficacy measure was endpoint mean pain score from daily pain diaries. Secondary efficacy measures included endpoint mean sleep-interference score from daily sleep diaries and Patient Global Impression of Change (PGIC). Safety evaluations included adverse events (AEs), physical and neurologic examinations, 12-lead ECG, vital signs, and laboratory testing. RESULTS: Pregabalin provided significant, dose-proportional pain relief at endpoint: difference from placebo in mean pain score, 150 mg/day, -0.88, p = 0.0077; 300 mg/day, -1.07, p = 0.0016; 600 mg/day, -1.79, p = 0.0003. Weekly mean pain scores significantly improved as early as week 1. Sleep interference in all pregabalin groups was also significantly improved at endpoint, compared with placebo (p < 0.001), beginning at week 1 (p < 0.01). At study termination, patients in the 150 (p = 0.02) and 600 mg/day (p = 0.003) groups were more likely to report global improvement than were those in the placebo group. Most AEs were mild or moderate. Among pregabalin-treated patients, 13.5% withdrew due to AEs, most commonly for dizziness (16 patients, 5.8%), somnolence (8, 2.9%), or ataxia (7, 2.5%). CONCLUSIONS: Pregabalin, dosed BID, reduced neuropathic pain associated with PHN and was well tolerated. It also reduced the extent to which pain interfered with sleep. Pregabalin's effects were seen as early as week 1 and were sustained throughout the 13-week study.

A cross-sectional survey of health state impairment and treatment patterns in patients with postherpetic neuralgia.

BACKGROUND: Postherpetic neuralgia (PHN) develops in 8-24% of patients with herpes zoster. Few studies have evaluated the patient burden and treatment of PHN in general practice. OBJECTIVES: To determine the patient burden of PHN with respect to pain intensity and impact on patient functioning and to characterise treatment patterns and health resource utilisation in general practice. METHODS: Eighty-four patients with PHN were identified in general practice settings during an observational survey of neuropathic pain syndromes in six European countries. Patients answered a questionnaire that included: pain severity and interference items from the modified short form brief pain inventory (mBPI-SF); EuroQol (EQ-5D) survey; and questions related to current treatment, health status and resource utilisation. Physicians provided information on medications prescribed for PHN and pain-related co-morbidities (anxiety, depression and sleep disturbance). RESULTS: Mean patient age was 71.0 +/- 12.8 years, 76% were > or = 65 years and 45% of patients had PHN > or = 1 year. The mean pain severity index was 4.2, reflecting moderate pain despite 89% of patients taking prescription medications for PHN. Few medications with demonstrated efficacy against PHN (e.g. carbamazepine and gabapentin) were prescribed, often at suboptimal doses. Pain severity was associated with reduced EQ-5D health state valuation (P<0.001), greater pain interference on all domains (P<0.001) and increased health resource utilisation (P = 0.008). CONCLUSIONS: PHN causes substantial patient burden expressed as interference with daily functioning and reduced health status associated with pain severity. This burden may result in part from suboptimal management strategies and suggests a need for more effective pain management.