Subgroups in chronic low back pain patients - a step toward cluster-based, tailored treatment in inpatient standard care: On the need for precise targeting of treatment for chronic low back pain.

Objective: The purpose of this study was to find applicable clusters for the development of different treatment pathways in an inpatient multimodal pain-therapy setting based on the multifaceted nature of CLBP. Methods: Based on data of questionnaires (Hospital Anxiety and Depression Scale (HADS), Marburg Questionnaire on Habitual Health Findings (MFHW), quality of life assessment using the Short-Form 12 (SF 12)), a retrospective two-step cluster analysis involving a sample of chronic low back pain (CLBP) patients (N=320) was calculated. Subsequently, the clusters were precisely described and compared on the basis of further data collected during the patients' standard care: pain characteristics, socio-demographic data and the general state of health, psychological variables, therapy intensity, and Diagnosis Related Groups (DRG) data. Results: We found a three-cluster solution: little psychological interference but marginal physical and mental quality of life (Cluster 1); poor well-being, low physical quality of life, and marginal mental quality of life (Cluster 2); and heavy mental strain and marginal physical quality of life (Cluster 3). Conclusions: Similar to previous studies, our results suggest that patients suffering from CLBP differ with regard to the magnitude of mental burden and the presence of physical impairment. These differences ascertain the need for precise targeting of treatment for CLBP. Inpatient pain centers therefore should offer different multimodal therapy pathways and integrate a meaningful triage, taking into account the multifaceted nature of CLBP based on sophisticated knowledge about forms, differences, and relationships among the biopsychosocial components of CLBP.

Pain-related avoidance versus endurance in primary care patients with subacute back pain: psychological characteristics and outcome at a 6-month follow-up.

Recent research has found individual differences in back pain patients due to behavioral avoidance vs persistence. However, there is a lack of prospective studies of nonspecific low back pain patients. The avoidance-endurance model (AEM) suggests at least 3 pathways leading to chronic pain: fear-avoidance response, distress-endurance response, and eustress-endurance response. We sought to compare these 3 maladaptive subgroups with an adaptive group using a classification tool that included the following scales: the thought suppression and behavioral endurance subscale of the Avoidance-Endurance Questionnaire and the Beck Depression Inventory. The psychological characteristics, and pain and disability of the AEM subgroups were investigated. We report results from 177 patients with subacute nonspecific low back pain at the start of outpatient treatment and at follow-up after 6 months. At baseline, a multivariate analysis of variance found that the fear-avoidance patients scored higher in pain catastrophizing than the other groups. The distress-endurance patients displayed elevated anxiety/depression and helplessness/hopelessness accompanied with the highest scores in the classification variables thought suppression and persistence behavior. The eustress-endurance patients had the highest humor/distraction scores, pain persistence, and positive mood despite pain. All 3 maladaptive groups revealed a higher pain intensity than the adaptive patients at follow-up after 6 months; however, disability at follow-up was elevated only in the fear-avoidance and distress-endurance patients. The study provides preliminary evidence for the construct and prospective validity of AEM-based subgroups of subacute, nonspecific back pain patients. The results suggest the need for individually targeted cognitive behavioral treatments in the maladaptive groups.

Validation and reliability of the German version of the Chronic Pain Grade questionnaire in primary care back pain patients.

In 1992 Von Korff and his co-workers developed a simple, brief questionnaire to assess the severity of chronic pain problems, the Chronic Pain Grade (CPG). The present study was conducted to analyse the psychometric properties of the translated German version of the CPG within a population of primary care back pain patients (n=130). Factor analysis yielded two factors which accounted for 72% of the variance of the questionnaire. The first factor 'Disability Score' (53.56% of the variance) revealed a good internal consistency (alpha=.88), the internal consistency of the second factor 'Characteristic Pain Intensity' was moderate (alpha=.68). The reliability of the whole instrument was good (alpha=.82). The CPG and its subscales show moderate to high relations with other instruments assessing the patient's disability (FFbH-R, Pain Disability Index PDI). Additionally weak to moderate but significant correlations were found between the CPG and other measures of grading and staging chronic pain (MPSS, RGS). Further, positive correlations between the CPG and both, the frequency of doctor visits and the frequent use of pain medication have been seen. The reported findings suggest, that the German version of the CPG is a reliable, valid and useful instrument if a brief, simple method of grading the severity of chronic pain is needed. The German version leads to a better comparability between German and English language studies and facilitates an international collaboration in this field of research.