The journal of pain : official journal of the American Pain Society
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Multicenter Study
Neuropathic aspects of persistent postsurgical pain: a French multicenter survey with a 6-month prospective follow-up.
To investigate the role of peripheral neuropathy in the development of neuropathic postsurgical persistent pain (N-PSPP) after surgery, this French multicentric prospective cohort study recruited 3,112 patients prior to elective cesarean, inguinal herniorrhaphy (open mesh/laparoscopic), breast cancer surgery, cholecystectomy, saphenectomy, sternotomy, thoracotomy, or knee arthroscopy. Besides perioperative data collection, postoperative postal questionnaires built to assess the existence, intensity, and neuropathic features (with the Douleur Neuropathique 4 Questions [DN4]) of pain at the site of surgery were sent at the third and sixth months after surgery. In the 2,397 patients who completed follow-up, the cumulative risk of N-PSPP within the 6 months ranged from 3.2% (laparoscopic herniorrhaphy) to 37.1% (breast cancer surgery). Pain intensity was greater if DN4 was positive and decreased with time since surgery; it depended on the type of surgery. In pain-reporting patients, the response to the DN4 changed from time to time in about 1:4 of the cases. Older age and a low anxiety score were independent protective factors of N-PSPP, whereas a recent negative event, a low preoperative quality of life, and previous history of peripheral neuropathy were risk factors. The type of anesthesia had no influence on the occurrence of N-PSPP.
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Assessing if an individual patient has achieved clinically meaningful changes in pain intensity is a core aspect in the evaluation of pain treatments. The aim of the present study was to define minimally clinically significant differences (MCSDs) for the numerical rating scale (0-10 NRS) in adolescents with chronic pain. Data from 153 adolescents who completed an inpatient treatment were analyzed. MCSDs were defined as those cut points that yielded an optimal balance between sensitivity and specificity with regard to patients' global impression of change. The variability of the empirically defined cut points was quantified using bootstrapping. Our results show that raw changes of 1 NRS point and percent changes of 12.5% can be considered MCSDs both within the full sample and within various subsamples of patients. Applying the MCSDs developed for adults to pediatric patients yielded extremely low sensitivities; for example, only 22% of the children who described global improvement met the 50% decrease in pain criterion. Studies evaluating chronic pain treatments for adolescents should use MCSDs that are specifically developed for this group of patients. Raw changes of 1 point and 12.5% on the 0 to 10 NRS should be considered clinically meaningful. On a methodological level, we call for more systematic studies aimed at defining MCSDs that also address the variability of cut point estimates so as to foster the integration of findings. ⋯ Many studies are aimed at empirically defining cut points for clinically relevant pain using receiver operating characteristic-based methods. For the first time, we apply these methods to children and show that even when taking into account the variability of the method, cut points specific for children are needed.
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Comparative Study
Comparison of back pain prognostic risk stratification item sets.
Back pain outcomes may be improved and costs lowered through risk-stratified care, but relative performance of alternative item sets for predicting back pain outcomes has not been well characterized. We compared alternative prognostic item sets based on STarT Back and Chronic Pain Risk screeners in a cohort of patients initiating primary care for back pain. The STarT Back item set was brief and relied on binary responses, whereas the Chronic Pain Risk item set employed scaled responses and assessed pain persistence and diffuse pain. Patients (N = 571) were assessed soon after their initial visit and 502 (88%) were reassessed 4 months later. Items sets based on STarT Back and Chronic Pain Risk prognostic screeners, as well as a combination of items from both, were used to predict Chronic Pain Grade II-IV back pain at 4 months. The area under the receiver operating characteristic curve estimates (95% confidence intervals) were .79 (.74-.83) for items based on the STarT Back, .80 (.75-.83) for items based on Chronic Pain Risk, and .81 (.77-.85) for a composite item set. Differences in prediction were modest. Items from 2 prognostic screeners, and both combined, achieved acceptable and similar prediction of unfavorable back pain outcomes. ⋯ Given comparable predictive validity, choice among prognostic item sets should be based on clinical relevance, number of items, ease of administration, and item simplicity.
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Chronic pain is influenced by biological, psychological, social, and cultural factors. The current study investigated potential roles for combinations of genetic and psychological factors in the development and/or maintenance of chronic musculoskeletal pain. An exercise-induced shoulder injury model was used, and a priori selected genetic (ADRB2, COMT, OPRM1, AVPR1 A, GCH1, and KCNS1) and psychological (anxiety, depressive symptoms, pain catastrophizing, fear of pain, and kinesiophobia) factors were included as predictors. Pain phenotypes were shoulder pain intensity (5-day average and peak reported on numerical rating scale), upper extremity disability (5-day average and peak reported on the QuickDASH), and shoulder pain duration (in days). After controlling for age, sex, and race, the genetic and psychological predictors were entered as main effects and interaction terms in separate regression models for the different pain phenotypes. Results from the recruited cohort (N = 190) indicated strong statistical evidence for interactions between the COMT diplotype and 1) pain catastrophizing for 5-day average upper extremity disability and 2) depressive symptoms for pain duration. There was moderate statistical evidence for interactions for other shoulder pain phenotypes between additional genes (ADRB2, AVPR1 A, and KCNS1) and depressive symptoms, pain catastrophizing, or kinesiophobia. These findings confirm the importance of the combined predictive ability of COMT with psychological distress and reveal other novel combinations of genetic and psychological factors that may merit additional investigation in other pain cohorts. ⋯ Interactions between genetic and psychological factors were investigated as predictors of different exercise-induced shoulder pain phenotypes. The strongest statistical evidence was for interactions between the COMT diplotype and pain catastrophizing (for upper extremity disability) or depressive symptoms (for pain duration). Other novel genetic and psychological combinations were identified that may merit further investigation.
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Complex regional pain syndrome (CRPS) is a distressing and difficult-to-treat complication of wrist fracture. Estimates of the incidence of CRPS after wrist fracture vary greatly. It is not currently possible to identify who will go on to develop CRPS after wrist fracture. In this prospective cohort study, a nearly consecutive sample of 1,549 patients presenting with wrist fracture to 1 of 3 hospital-based fracture clinics and managed nonsurgically was assessed within 1 week of fracture and followed up 4 months later. Established criteria were used to diagnose CRPS. The incidence of CRPS in the 4 months after wrist fracture was 3.8% (95% confidence interval = 2.9-4.8%). A prediction model based on 4 clinical assessments (pain, reaction time, dysynchiria, and swelling) discriminated well between patients who would and would not subsequently develop CRPS (c index .99). A simple assessment of pain intensity (0-10 numerical rating scale) provided nearly the same level of discrimination (c index .98). One in 26 patients develops CRPS within 4 months of nonsurgically managed wrist fracture. A pain score of ≥5 in the first week after fracture should be considered a "red flag" for CRPS. ⋯ This study shows that excessive baseline pain in the week after wrist fracture greatly elevates the risk of developing CRPS. Clinicians can consider a rating of greater than 5/10 to the question "What is your average pain over the last 2 days?" to be a "red flag" for CRPS.