The course of depressive and anxiety disorders is worse in patients who also suffer from pain, according to results of a longitudinal study reported in the February 2012 issue of Pain.
Patients with depressive and/or anxiety disorders often report short-term and chronic physical pain. Cross-sectional studies and treatment trials have shown that pain might influence depressive and anxiety disorders, but they have not longitudinally examined the impact of pain on the course of depressive and anxiety disorders.
Marloes M.J.G. Gerrits of the EMGO Institute for Health and Care Research of the VU University Medical Center, Amsterdam, and her colleagues sought to investigate how much pain influences the 2-year course of these disorders and to what extent other psychiatric characteristics mediate them.
This study is part of the Netherlands Study of Depression and Anxiety (NESDA), an 8-year ongoing cohort study monitoring 2,981 participants to investigate the long-term course and consequences of depressive and anxiety disorders. The researchers restricted this study to subjects with a depressive and/or anxiety disorder who were symptomatic in the month prior to baseline. Of 1,456 eligible participants, 1,209 (83%) participated in the 2-year follow-up interview. The mean age of participants was 42.1 years, and 66% were female (Pain 2012;153:429-36).
For this study, Ms. Gerrits, a PhD candidate, and her colleagues assessed pain at baseline according to the specific location (joints, back, neck, abdomen, chest, head, and orofacial area), the number of locations (0-7), and which location had the greatest amount of pain. Additional measures of pain included duration of 90 days or more, use of pain medication within the last 6 months, and how often patients used medication (daily, weekly, monthly, sporadic, or no use). Finally, using the Chronic Pain Grade (CPG), the researchers measured the severity of chronic pain according to intensity and disability caused by the pain.
The researchers also assessed the course of depressive and anxiety disorders by conducting a Composite International Diagnostic Interview (CIDI) at baseline and after 2 years, and a Life Chart Interview.
At baseline, 22.1% of subjects had a depressive disorder only, 40.3% had an anxiety disorder only, and 37.6% had a comorbid disorder, the researchers found. The mean number of pain locations was 3.68, with headache the most often mentioned and orofacial pain the least mentioned. Almost half of the patients (41.4%) had at least 90 days of pain in the past 6 months, and 10.3% used pain medication daily. Also, 27.1% of subjects were highly disabled from chronic pain (grades 3 and 4 on the CPG), indicating severe chronic pain.
Within 6 months after baseline, 24.6% of subjects recovered from their depressive and/or anxiety disorder. Another 13.4% recovered after more than 6 months, 18.5% had at least one relapse during follow-up, and 43.5% had a chronic course for 2 years. At the 2-year follow-up, 61.5% of subjects were diagnosed with depressive and/or anxiety disorder within the previous 6 months.
A higher number of pain locations, joint pain, 90 days or more of pain, daily use of pain medication, and a higher CPG score all were associated with a significantly increased risk of still having a depressive or anxiety disorder after 2 years, the researchers found. Also, longer duration and higher severity of the pain were significantly associated with having a chronic course of depressive and/or anxiety disorders.
"These relationships were largely mediated by a greater severity of the baseline depressive and/or anxiety disorder among those with pain, except for pain of the joints, which remained a significant predictor after considering severity," the researchers reported.
The association between pain and a worse course of depression and/or anxiety may be tied to individuals being disabled regarding daily activities and physical and social roles. Also, chronic pain and depressive and anxiety disorders share pathophysiologic pathways. "That severity of the index depressive and/or anxiety disorder mediated the effects of pain on depression and anxiety course is in line with this, as the most severe depression and anxiety patients will show the largest dysregulations of central stress systems," the researchers noted.
The study’s findings emphasize the importance of asking depressed and anxiety patients about pain. Also, the results suggest that treatment specific for depression and anxiety patients with pain is warranted, the researchers said.
The authors declared that they have no conflict of interest. The infrastructure for the NESDA study is funded through the Netherlands Organization for Health Research and Development and is supported by participating universities and mental health care institutions.