High Prevalence of Neuropathic Pain Features in Patients with Knee Osteoarthritis: A Cross-Sectional Study.

OBJECTIVE: The present epidemiological research evaluated the prevalence of neuropathic pain characteristics in patients with painful knee osteoarthritis (OA) and the plausibility that such neuropathic features were specific of OA. METHODS: Outpatients with chronic pain associated with knee OA who attended orthopedic surgery or rehabilitation clinics were systematically screened for neuropathic pain with the Douleur Neuropathique in 4 questions (DN4) questionnaire. Data from medical files and those obtained during a single structured clinical interview were correlated with the DN4 scores. Information on potential confounders of neuropathic-like qualities of knee pain was collected to evaluate as much as possible only the symptoms attributable to OA. RESULTS: Of 2,776 patients recruited, 2,167 patients provided valid data from 2,992 knees. The DN4 was scored positively (≥ 4) in 1,125 patients (51.9%) and 1,459 knees (48.8%). When patients with potential confounders were excluded, the respective prevalences were 33.3% and 29.4%. Patients who scored positively in the DN4 had more severe pain, greater structural damage, and more potential confounders of neuropathic pain. Three potential confounders conveyed much of the variability explained by regression analyses. However, latent class analyses revealed that the concourse of other factors is required to explain the neuropathic pain qualities. CONCLUSIONS: A relevant proportion of patients with chronic pain associated with knee OA featured neuropathic pain qualities that were not explained by other conditions. The present research has provided reasonable epidemiological grounds to attempt their definite diagnosis and classification.

Chronic noncancer pain intensity is inversely related to analgesic adherence in pain clinics.

OBJECTIVE: The relationship between chronic noncancer pain (CNCP) control and pain medication (analgesic) adherence has not been widely documented. The primary aim of this study was to evaluate the relationship between pain intensity and the degree of adherence to analgesic medication prescribed in pain clinics. There was also a special emphasis on the influence of polypharmacy on adherence. METHODS: A cross-sectional clinical survey was carried out in pain clinics across Spain. Demographic and clinical data were collected from patients: pain intensity, analgesic prescription and adherence, and the presence of concomitant medical conditions and treatments. The relationship between analgesic adherence and pain intensity was analyzed using correlations and propensity scores based on ordinal logistic regression. Correlates of pain intensity were explored using multiple linear regression. RESULTS: Data was gathered from 1407 patients; 1321 were eligible for analysis. Their mean (standard deviation) age was 61.6 (14.7) years and the majority (67.3%) were women. More than half (57.9%) received step 3 analgesics. Pain intensity was scored 5 out of 10 on average. Just 65.9% of patients were reported to not have missed any analgesic dose during the previous week. Pain intensity correlated negatively with analgesic adherence (r(s) = -0.151, p < 0.001). Moderate versus very intense pain was predicted in patients with 'good' and 'very poor' adherence, respectively. The presence of concomitant medications also correlated negatively with analgesic adherence (r(s) = -0.074, p = 0.007). However, few investigators reported such a negative effect of polypharmacy. LIMITATIONS: Key limitations of this research are its cross-sectional design and the absence of an objective means of measuring medication adherence. CONCLUSIONS: This study has shown that there is a small but significant inverse relationship between analgesic adherence and CNCP control, which has remained elusive to date and should be further evaluated. Polypharmacy also had a negative influence on adherence, although this was not acknowledged by all investigators.

Psychometric validation of the neuropathic pain symptom inventory for its use in Spanish.

CONTEXT: Clinical instruments are required for the assessment of neuropathic pain (NP). OBJECTIVES: The primary aim of this study was to perform a complete psychometric validation of the Neuropathic Pain Symptom Inventory (NPSI) in Spanish patients. METHODS: A linguistically validated version in Spanish of the NPSI and other clinical instruments for NP were administered on two occasions separated by at least one month to 548 patients suffering from chronic NP. The authors evaluated the responsiveness, the construct validity, and the internal structure of the NPSI by means of, respectively, receiver operating characteristic (ROC) curves analysis and calculation of reliable change indices, a multitrait-multimethod (MTMM) design, and primary component analysis. Internal consistency and test-retest reliability were evaluated, respectively, by calculating several Cronbach's alpha coefficients and intraclass correlation coefficients of some scores selected appropriately. RESULTS: The areas under the ROC curves were greater than 0.85. The MTMM design found convergent-discriminant correlations correctly aligned for all NPSI subscores in the first assessment, and for all but paresthesia/dysesthesia subscores in the second assessment. The five components of the NPSI described by its authors were confirmed on one occasion, but the "electric shocks" and "stabbing" items did not associate consistently, as in the original version, the first time the NPSI was administered. All reliability coefficients were above 0.70. CONCLUSION: The Spanish NPSI has good concurrent and construct validity and is reliable for a wide range of patients with NP. One exception to the original structure was found affecting one item, presumably relating to a cultural feature.

Transdermal buprenorphine for the treatment of cancer pain: results from a multicenter, observational, post-marketing study in Spain (RELIEF study).

UNLABELLED: SUMMARY  AIM: This study evaluated health outcomes in patients with cancer pain during treatment with transdermal buprenorphine, including quality of life, effectiveness, tolerability, and functional consequences for patients and their carers. METHODS: In this 3-month, noncomparative, multicenter, observational study performed in a normal clinical practice setting in Spain, patients received transdermal buprenorphine 37, 52.5 or 70 µg/h, with patches changed every 96 h. The effect of transdermal buprenorphine on quality of life (primary study focus) was assessed using the Visual Analog Scale (VAS) component of the EuroQol 5 Dimensions™ (EQ-5D). In addition, pain (assessed using the Brief Pain Inventory - Short Form [BPI-SF] and VAS-pain), the impact of pain on patients and carers (assessed using the Beck Depression Inventory, sleep quality analysis, VAS-patient limitation, VAS-carer limitation and the Palliative Care Scale), patient's use of health resources, patient satisfaction, and tolerability, were evaluated. RESULTS: Of 116 patients entering the study, 42 completed the 3-month study period. Five patients withdrew due to adverse events. The two main reasons for study discontinuation were nontreatment-related death (27.1%) and lost to follow-up (18.8%). The mean age was 62.9 years and the mean baseline duration of pain was 7.78 weeks. In the month prior to starting transdermal buprenorphine, 80% of patients had received at least one nonopioid analgesic medication; 21% had received an opioid analgesic (most commonly tramadol). The most common dose of transdermal buprenorphine used was 35 µg/h. The mean improvement from baseline in the EQ-5D VAS score among 65 patients with data was 15.20 ± 24.96 (p < 0.0001). EQ-5D descriptive parameters also improved during the study (not statistically significant). Mean improvements in BPI scores for worst pain (3.76) and average pain (3.03) were significant (p < 0.0001). The other measures of pain relief also supported transdermal buprenorphine as an effective analgesic. Sleep quality improved during the study. VAS scores (100 mm scale) for patient limitation and caregiver burden due to pain improved, with a significant mean change in VAS-carer limitation score (30.34; p < 0.0001). Adverse events were reported by ten (8.6%) patients, most commonly affecting the gastrointestinal system (vomiting [4.3% of patients], nausea [2.6%] and constipation [0.9%]). The majority of patients reported satisfaction with their analgesic treatment. CONCLUSIONS: In this observational study in normal clinical practice, transdermal buprenorphine provided effective pain relief and was generally well tolerated by patients with cancer pain. It also improved quality of life for patients and reduced caregiver burden. Considering the high number of study discontinuations (mainly due to nontreatment-related death and lost to follow-up), the results of this study need to be evaluated with caution.