New results from a large national survey show that the association between anxiety disorders and arthritis and low back pain may be stronger than that of depression and the 2 pain syndromes, a finding that has the potential to guide clinicians in the treatment of these comorbid conditions.1

Most prior studies have shown pain conditions to be associated primarily with depression2-4 and scarce research data have been provided on other domains of psychopathology as they relate to pain. The present study results, published in a recent issue of the journal Pain, show positive and statistically significant associations between arthritis and low back pain and 2 anxiety disorders (generalized anxiety disorders [GADs] and panic attacks) in addition to depression. A subanalysis of the data indicated clearly that each pain condition was more strongly associated with the anxiety disorders than with depression.

In a study that included 588 adults (25 to 74 years of age), the researchers found that there was a 2-fold increase in reported panic attacks and GAD in patients with arthritis, 11.2% and 5.6%, respectively, compared with those without the disorder, 5.8% and 2.7%, respectively (P <.001). In contrast, 18.2% of participants with arthritis frequently reported depression, compared with 13.1% among those with no arthritis (P <.001).

The stronger associations had been noted in an earlier study by the current investigation's lead author Lachlan A. McWilliams, a PhD candidate in clinical psychology at the University of Manitoba in Winnipeg, Canada, and psychology intern at the Royal Ottawa Hospital, also in Winnipeg. "In that study," he told CIAOMed, "I found the associations involving anxiety disorders were often larger than the association between arthritis and depression." Specifically, those results show that the relationships of arthritis with panic disorder and posttraumatic stress disorder are stronger than those with depression.5

"This was surprising," Dr. McWilliams said, "because the psychosocial literature on pain has placed much more emphasis on depression."

Whereas previous epidemiological studies of psychopathological associations with arthritis pain have not adjusted for the presence of another pain condition, in the current investigation multivariate analyses indicated that the associations remained consistent after adjusting for comorbid pain conditions.

In addition, Dr. McWilliams observed that the new study suggests that findings related to anxiety may also apply to pain conditions other than arthritis. Among the 614 patients with low back pain in the current investigation, the prevalence of anxiety disorders are shown to be significantly associated with low back pain (P <.001). Panic attacks were reported by 13.0% of participants with low back pain vs 5.3% without this pain condition and GADs were reported by 6.2% with low back pain vs 2.5% without low back pain. Percentage comparisons were less dramatic for those with low back pain who reported depression; 21.0% of patients who had this pain condition reported depression whereas 12.4% did not.

After adjusting for a wide range of potential confounding demographic variables, including age, gender, education level, and race, most of these associations remained statistically significant, with those between pain and anxiety disorders generally larger than those between pain and depression.

Past studies addressing the relationship between pain conditions and psychopathology have been limited by their use of nonrepresentative samples (eg, clinical samples). Results relating to prevalence rates and associations in these studies were apt to have been biased by the use of highly selected patients enrolled in specialty pain treatment centers.

Data from the Midlife Development in the United States Survey (MIDUS) were utilized for the present study. The large sample (N = 3032) was representative of non-institutionalized civilian adults who had experienced health problems or medical conditions, including arthritis and low back pain, over the preceding 12 months. Female participants made up 56.5% of the sample, of whom 82.0% were Caucasian and ll.2% were African American, with the remaining 6.8% representative of other racial groups.

Participants completed several diagnostic-specific measures based on the Composite International Diagnostic Interview-Short Form (CIDI-SF) scales to identify past-year diagnoses of depression, GADs, and panic attacks (defined as discrete episodes of intense fear or discomfort occurring in situations that do not typically cause anxiety, with characteristic symptoms including rapid heart beat, increased perspiration, and shaking).

The study authors speculated that in an effort to reduce the somatic arousal associated with pain, the individuals with pain conditions in this study may use worry as a coping strategy and, therefore, be more prone to develop GAD.

"Anxiety disorders often go undetected in the clinical setting and there is evidence that comorbid psychopathology is associated with increased disability and poorer treatment outcomes," Dr. McWilliams said. "Given this situation and my findings, it is likely that patient care could be improved by increasing efforts to detect and treat anxiety disorders amongst those presenting with pain. Those patients with anxiety disorders are typically reluctant to disclose their anxiety-related difficulties, so specific, evidence-based strategies would be required to improve on this front."

Future directions for investigations of the relationships of pain conditions to psychopathology have potentially great importance for clinical practice. "I would be particularly interested in developing and testing strategies aimed at assisting general practitioners in detecting anxiety disorders and optimally managing the care of patients with pain and anxiety disorders," Dr. McWilliams noted.

The study was supported by a fellowship from the Health Sciences Centre Foundation and grants from the Canadian Institutes of Health Research, the Canadian Foundation for Innovation, and the Canada Research Chairs program.

References:

  1. McWilliams LA. Goodwin RD, Cox BJ. Depression and anxiety associated with three pain conditions: results from a nationally representative sample. Pain. 2004;111:77-83.
  2. Bair MJ, Robinson RL, Katon W, Kroenke K. Depression and pain comorbidity: a literature review. Arch Intern Med. 2003;163:2433-2445.
  3. Currie SR, Wang J. Chronic back pain and major depression in the Canadian population. Pain. 2004;107:54-60.
  4. Fishbain DA, Cutler R, Rosomoff HL, Rosomoff RS. Chronic pain-associated depression: antecedent or consequence of chronic pain? A review. Clin J Pain. 1997;13:116-137.
  5. McWilliams LA, Cox BJ, Enns MW. Mood and anxiety disorders associated with chronic pain: an examination in a nationally representative sample. Pain. 2003;106:127-133.