Effects of mood state and psychosocial functioning on plasma interleukin-6 in adult patients before cardiac surgery

Objective: The purpose of this study was to examine the potential effect of mood states and psychosocial functioning during the waiting weeks prior to major cardiac surgery on the plasma Interleukin-6 (IL-6) levels in 236 patients immediately before their operation. Method: The sample was recruited from patients at the cardiac clinic of the University of Michigan Medical Center (Ann Arbor). Two weeks before cardiac surgery, trained research assistants conducted a face-to-face interview with these middle-aged and older patients on their preoperative physical examination date at the clinic. Standardized instruments were used to assess mood states and psychosocial functioning. The blood samples of 236 patients, obtained on the morning of the operation, were analyzed for plasma IL-6. Results: In bivariate analysis, poor psychological functioning and anxiety, as well as bodily pain and body mass index (BMI), were correlated with plasma IL-6 (p < .05), but sociodemographics, chronic illness and use of psychotropic medications were not. When the effect of bodily pain and BMI were taken into account, partial correlation analysis showed that psychological functioning continued to be associated with plasma IL-6 (p < .05); the association of IL-6 with depression now became significant (p < .05), whereas that with anxiety became even more significant (p < .001). Conclusions: Preoperative psychological disturbances during the waiting weeks before cardiac surgery may influence the plasma levels of IL-6 immediately prior to the procedure. The clinical implications of these findings remain to be determined.