Effect of i.v. acetaminophen on total hip or knee replacement surgery: a case-matched evaluation of a national...

The effects of i.v. acetaminophen on adverse events, hospital length of stay (LOS), and overall hospital costs for total hip or knee replacements were evaluated.

We conducted a matched-pairs analysis of adult inpatients who underwent elective total hip arthroplasty or total knee arthroplasty in hospitals participating in the Premier Healthcare Alliance from January 1, 2011, to November 30, 2012. Each case who received i.v. acetaminophen on the day of surgery was matched to a control who did not receive i.v. acetaminophen within the same hospital. Treatment groups were analyzed for differences in the rate of adverse effects, LOS, and hospital resource utilization.

A total of 22,146 cases and controls were similar in terms of age, race, sex, marital status, insurance status, and preoperative comorbidities. Overall adverse events were significantly lower with i.v. acetaminophen (24.3%) than with controls (26.3%, p < 0.001), numerically less frequent in all subgroups, and significantly less frequent for renal, infectious, and miscellaneous adverse events (all p < 0.05). I.V. acetaminophen was also associated with a shorter LOS, with 1 out of 11 patients discharged one day earlier (p < 0.001) and lower average hospital costs: $16,381 for cases compared with $16,927 for controls (p < 0.001). Cost savings estimated by structural equation modeling of $547 per patient were due to $325 from direct effects and $222 from indirect effects, the latter mediated through adverse events and reduced LOS.

In this retrospective cohort study of case-matched patients who underwent total hip or knee replacement surgery, multimodal analgesia with i.v. acetaminophen was associated with improved clinical outcomes in terms of fewer adverse events, shortened LOS, and reduced total hospital resources compared with patients who did not receive i.v. acetaminophen.