Can We Use MDDScore for the Identification of Comorbid Major Depressive Disorder (MDD) in Patients with Chronic Pain?

Abstract

The prevalence of patients with chronic pain who display depressive symptoms is quite high, with depression potentially an integral component of chronic pain. Since the current subjective clinical diagnostic systems were not designed to assess depression in patients with chronic pain, they fail to adequately capture the nature of mood states of these patients. It is difficult to apply these assessment tools to segregate unipolar depression (MDD) from the demoralization inherent in chronic pain states. MDDScore™, a multivariate biomarker blood test for depression, was used to determine if it was possible to identify biomarker patterns consistent with major depressive disorder in multiple chronic pain states. Three study groups were analyzed, and included: (i) patients (n=93) with centralized Chronic Intractable Pain (CIP), (ii) patients (n=20) with chronic pain of diverse origin from Scripps Pain Clinic (SPC) and (iii) prospectively collected patients (n=28) with comorbid arthritis and depressive symptoms. A very distinct bimodal pattern was observed. Forty-nine of 93 CIP patients (52.7%), 18 of 28 (64.2%) of the arthritis patients, and 9 of 20 (45%) patients with chronic pain of diverse origin from Scripps Pain Clinic had MDDScores of ≥5. Thus, the biomarker panel could segregate patients into two major groups based upon MDDScores. These data suggest but not prove we can objectively identify chronic pain patients with a higher probability of comorbid major depression. Importantly, we can use the biomarkers on the MDDScore panel to gain insight into and gauge the residual (post-treatment) level of inflammation in these intensively treated patients. To this end, we determined and compared the serum concentrations of alpha-1 antitrypsin (A1AT), Myeloperoxidase (MPO) and soluble tumor necrosis factor receptor type 2 (sTNFR2) in each of the patient populations studied.