Association of depression and anxiety alone and in combination with chronic musculoskeletal pain in primary care patients

Abstract

Objective: To assess the relationship between depression and anxiety comorbidity on pain intensity, pain-related disability, and health-related quality of life (HRQL).

Methods: Analysis of baseline data from the Stepped Care for Affective Disorders and Musculoskeletal Pain (SCAMP) study. All patients (n = 500) had chronic pain (>or=3-month duration) of the low back, hip, or knee. Patients with depression were oversampled for the clinical trial component of SCAMP and thus represented 50% of the study population. Patients were categorized according to pain comorbid with depression, anxiety, or both. We used analysis of variance and multivariate analysis of variance models to assess the relationships between independent and dependent variables.

Results: Participants had a mean age of 59 years; they were 55% women, 56% White, and 40% Black. Fifty-four percent (n = 271) reported pain only, 20% (n = 98) had pain and depression, 3% (n = 15) had pain and anxiety, and 23% (n = 116) had pain, depression, and anxiety. Patients with pain and both depression and anxiety experienced the greatest pain severity (p < .0001) and pain-related disability (p < .0001). Psychiatric comorbidity was strongly associated with disability days in the past 3 months (p < .0001), with 18.1 days reported by patients with pain only, 32.2 days by those with pain and anxiety, 38.0 days by those with pain and depression, and 42.6 days in those with all three conditions. We found a similar pattern of poorer HRQL (p < .0001) in those with pain, depression, and anxiety.

Conclusions: The added morbidity of depression and anxiety with chronic pain is strongly associated with more severe pain, greater disability, and poorer HRQL.

Figure 1. Pain severity and pain interference by pain only and pain with psychiatric comorbidity groups

* Unadjusted group means with standard errors (displayed as error bars) comparing pain severity and pain interference across four clinically defined groups using analysis of variance (ANOVA) tests; main effect of group status (pain only, pain and anxiety, pain and depression, and pain, depression, and anxiety). For pain severity and interference, the overall F test value is significant (P < 0.001) for increasing severity and interference when pain is comorbid with depression and/or anxiety. ¹Score range: 0 (none) to 10 (most severe) as assessed by Brief Pain Inventory ²Score range: 0 (no interference) to 10 (completely interferes) as assessed by Brief Pain Inventory

Figure 2. Health-related quality of life by pain only and pain with psychiatric comorbidity groups *

* The decrement in subscale scores of the Medical Outcomes Study SF-20 are shown across the four clinically defined groups: pain only, pain and anxiety, pain and depression, and pain, depression, and anxiety groups. For each SF-20 subscale, the overall F test value is significant (P < 0.001) for declining function when pain is comorbid with depression and/or anxiety