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