Should Unexplained Painful Physical Symptoms be Considered within the Spectrum of Depressive Symptoms?

Objective: To examine whether painful physical symptoms (PPS) can be considered within the spectrum of depressive symptoms.

Methods: Data for this post-hoc analysis were taken from a 6-month observational study mostly conducted in East Asia, Mexico, and the Middle East of 1,549 depressed patients without sexual dysfunction at baseline. Both explanatory and confirmatory factor analyses (EFA and CFA) were performed on the combined items of the 16-item Quick Inventory of Depressive Symptomatology Self-Report and the Somatic Symptom Inventory (seven pain-related items only). An additional second-order CFA was also conducted to examine an association between retained factors and the overall "depressive symptoms" factor. In addition, Spearman's correlation was used to assess levels of correlation between retained factors and depression severity as well as quality of life.

Results: Both EFA and CFA suggested and validated a four-factor solution, which included a pain factor. The other three factors identified were a mood/cognitive factor, a sleep disturbance factor, and an appetite/weight disturbance factor. All four factors were significantly associated with the overall factor of depression. They were also highly correlated to depression severity and quality of life (p<0.001 for all). The levels of correlations with the pain factor were generally greater than those with the appetite/weight factor and similar to those with the sleep factor.

Conclusion: It may be reasonable to consider PPS within a broad spectrum of depressive symptoms. At least, they should be routinely assessed in patients with depression. Further research is warranted to validate these preliminary findings.