Preoperative anxiolytic and antidepressant medications as risk factors for increased opioid use after total knee arthroplasty: a matched retrospective cohort analysis

Introduction:
Previous literature has suggested that the presence of anxiety or depression may be linked to increased postoperative pain. The objective of this retrospective analysis was to assess whether patients who use anxiolytics or antidepressants preoperatively were associated with worse acute pain outcomes after elective total knee arthroplasty (TKA).

Material and methods:
A chart review of patients who underwent TKA at our institution was conducted. The primary outcome was mean opioid use in oral morphine equivalents (OME) on the day of surgery (POD 0) through postoperative day 1 (POD1). Secondary outcomes included median pain scores during hospitalization, the need for an acute pain service (APS) consultation, and mean length of stay. Patients were matched (1 : 1) according to multiple factors including age, surgical anaesthesia type, preoperative pain scores, and placement of a single-injection adductor canal block.

Results:
83 patients were successfully matched in each group. During POD0-1, patients with anxiolytic or antidepressant prescriptions required a mean of 101.36 mg OME (SD = 66.89), compared to 86.78 mg (SD = 62.66) among patients without use of these medications (P = 0.011) (estimate of average treatment effect of +22.86). Similarly, these patients were more likely to report a slightly higher median pain score than patients not taking anxiolytics or antidepressants (4.00 [SD 1.95] vs. 3.77 [SD 2.01], P = 0.031) (estimate of average treatment effect of +0.55). However, there were no differences in hospital length of stay, acute pain service consultation, visit to an Emergency Department within one week of discharge, and readmission within one week of discharge. There were also no differences in outcomes when comparing patients with a history of anxiety or depression to those without this history.

Conclusions:
The use of chronic anxiolytics or antidepressants was associated with increased opioid use and slightly higher pain scores in patients undergoing TKA. These associations were independent of a medical diagnosis of anxiety or depression. The mode­rate increase in perioperative opioid consumption and pain scores was not associated with an increase in APS consultations or length of stay.