AN EMPIRICAL-EVALUATION OF MULTIDIMENSIONAL CLINICAL OUTCOME IN CHRONIC LOW-BACK-PAIN PATIENTS

Individuals with persisting pain often present a constellation of symp toms 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 multidim ensional assessment, no empirical efforts have validated the construct of a multidimensional clinical outcome presentation based on the dime nsions of pain, impairment and dysphoric mood. We employed cluster ana lytic procedures on standard measures of pain, impairment and depressi on in chronic low back pain (CLBP) patients (n = 96) attending a gener al orthopedic clinic in order to empirically characterize multidimensi onal clinical outcomes. Results indicated that 3 groups could be ident ified reliably: (1) 'Chronic Pain Syndrome' (n = 25; high levels of pa in, 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 a nd depression). The reliability of this cluster solution was supported by several tests of internal consistency. Discriminability of the clu sters was examined across both the outcome measures themselves and sev eral additional independent variables. The cluster solution was then c ross-validated in an independent sample of pain clinic CLBP patients ( n = 180) to test its generalizability. Finally the stability of the cl uster dimensions over time was tested by re-assessing 36 CLBP patients 6 months after they initially were characterized into 1 of the 3 outc ome groups on the same measures. MANOVA results indicated that the out come groups were differentiated statistically across assessments. The multiple outcome measures did not change significantly across time, no r did the outcome groups change differentially across time on these me asures. We conclude that the outcome dimensions of pain, impairment an d depression are relatively stable phenomena that differentially descr ibe CLBP patients.