An empirical evaluation of multidimensional clinical outcome in chronic low back pain patients

Abstract

Individuals with persisting pain often present a constellation of symptoms that includes pain, health-related impairment and dysphoric mood. It is now widely accepted that comprehensive assessment must address each of these dimensions. Despite recognition of the value of multidimensional assessment, no empirical efforts have validated the construct of a multidimensional clinical outcome presentation based on the dimensions of pain, impairment and dysphoric mood. We employed cluster analytic procedures on standard measures of pain, impairment and depression in chronic low back pain (CLBP) patients (n = 96) attending a general orthopedic clinic in order to empirically characterize multidimensional clinical outcomes. Results indicated that 3 groups could be identified reliably: (1) 'Chronic Pain Syndrome' (n = 25; high levels of pain, impairment and depression), (2) 'Positive Adaptation to Pain' (n = 24; high levels of pain with low levels of impairment and depression) and (3) 'Good Pain Control' (n = 47; low levels of pain, impairment and depression). The reliability of this cluster solution was supported by several tests of internal consistency. Discriminability of the clusters was examined across both the outcome measures themselves and several additional independent variables. The cluster solution was then cross-validated in an independent sample of pain clinic CLBP patients (n = 180) to test its generalizability. Finally the stability of the cluster dimensions over time was tested by re-assessing 36 CLBP patients 6 months after they initially were characterized into 1 of the 3 outcome groups on the same measures. MANOVA results indicated that the outcome groups were differentiated statistically across assessments. The multiple outcome measures did not change significantly across time, nor did the outcome groups change differentially across time on these measures. We conclude that the outcome dimensions of pain, impairment and depression are relatively stable phenomena that differentially describe CLBP patients.

Race, age, and gender influences among clusters of african american and white patients with chronic pain

“…14,36,66,74 Both clusters have been repeatedly identified in the literature among patients with chronic pain and also among patients with more specific etiology such as low back pain, spinal pain, temporomandibular joint disorders, and headache. 5,46,64,76 Rudy et al 64 identified a dysfunctional profile (42.6%, all high) and a minimizer/ adaptive coper profile (29.5%, all low), similar to our findings. When tested, their clusters were not related to gender, age, pain duration, or number of medical conditions by using the IASP classification.…”

“…Klapow et al used similar dimensions to classify their study sample and identified a group of patients with high pain, low depression, and low pain impact. 46 The differences between our results and theirs might be related to the measures (MPQ, Sickness Impact Profile, and BDI) and the sample used (men with chronic low back pain without any major comorbidities). Our study used a mixed pain model, an ethnically diverse population, and included both men and women who had comorbid conditions.…”

“…15,21,22,46,55,63,64 Several authors have presented arguments regarding previous classification methods and their feasibility when used in clinical settings: (1) the International Association for the Study of Pain (IASP) classification is dependent on pain site only, (2) the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) emphasizes the assessment of mental functioning and psychopathology, and (3) the Minnesota Multiphasic Personality Inventory (MMPI) was not devised to assess functioning in patients with chronic pain. 15,22,41,54,73 Sanders and Brena 66 compared the pain-related outcomes in subgroups of patients with chronic pain by using a disability measure and medical conditions, but pain and depression were not included as clustering factors.…”

“…Three classification measures were used: pain severity (MPQ), depression (BDI), and pain interference with functioning (PDI), as previously proposed by Klapow et al 46 In their description, pain outcomes were identified as intrinsically different from process factors or dimensions such as coping, personality, and physical pathology. The latter (process factors) are thought to influence pain outcomes and are not recognized as outcomes themselves.…”

“…Several authors have used taxonomic methodologies to identify subgroups of patients with chronic pain on the basis of the previously mentioned factors. 5,12,14,37,46,66,73,76 Two subgroups or clusters have been consistently identified across multiple studies. The first cluster is classically characterized by high pain outcome measures (ie, high pain severity, depression, and disability).…”