Exploratory factor analysis of the beck depression inventory: predictors of delayed opioid cessation after surgery in a pilot cohort study

Previously, we conducted a pilot cohort study of patients scheduled to undergo 5 distinct surgical procedures. (1) Pre-operative elevated depressive symptoms (every 10 point increase on the Beck Depression Inventory II-BDI) were associated with a 47% (95%CI 24%-64%) reduction in the rate of opioid cessation following surgery (p<0.0006).¹ Pre-operative legitimate opioid use and pre-operative self-perceived susceptibility to addiction were also significant predictors.¹ In contrast, pain severity and pain duration did not predict delayed opioid cessation after surgery. The BDI is validated for use with chronic pain patients, but certain patients score higher on somatic vs. cognitive-affective components of the test increasing the overall score. Also, the BDI is most useful for assessing depressive symptoms of higher severity. As an initial step to understanding how mood perpetuates opioid use after surgery, we conducted an exploratory factor analysis of the pre-operative BDI score. We identified three main factors characterized as negative affect, self-loathing, and somatic symptoms. All factors were significantly associated with delayed opioid cessation in univariate Cox regression, but multivariate analysis revealed self-loathing as the only significant factor of the BDI predicting delayed opioid cessation. Although there was some overlap between negative affect and somatic symptoms, which may have limited our study findings, this analysis reinforces the association of pre-operative affective state with delayed opioid cessation after surgery. Of note, other studies have identified these cognitive components of self-loathing apart from somatic symptoms on the BDI as a useful measure of depression. Future research is needed to address the complex relationship between mood, opioid use, and pain through surgery and recovery. (1. Carroll I, Barelka P, Wang CK, Wang BM, Gillespie MJ, McCue R, et al. A Pilot Cohort Study of the Determinants of Longitudinal Opioid Use After Surgery. Anesth Analg. 2012. Epub 2012/06/26. http://dx.doi.org/10.1213/ANE.0b013e31825c049f. PubMed PMID: 22729963.)