Retrospective Pharmacoeconomic Analysis of Perioperative use of Intraveneous Acetaminophen

Research Article

Austin J Anesthesia and Analgesia. 2014;2(3): 1020.

# Retrospective Pharmacoeconomic Analysis of Perioperative use of Intraveneous Acetaminophen

Anita Gupta1*, Lisa K Lee1, Sonali Rao1, Snigdha Aancha1, Cyrus Dadachanji1, Kirtanaa Voralu2

1Division of Pain Medicine & Regional Anesthesiology, Department of Anesthesiology and Perioperative Medicine, Drexel University College of Medicine, USA

2Clinical Research Group, Drexel University College of Medicine, USA

*Corresponding author: Anita Gupta, Pain Medicine and Regional Anesthesiology, Drexel University College of Medicine/ Hahnemann University Hospital, 230 N. Broad St Mailstop 310, Philadelphia PA 19102.

Received: February 18, 2014; Accepted: March 31, 2014; Published: April 10, 2014

## Abstract

Background: Pain is a growing public health problem that costs society $560–$635 billion annually. Using a potent analgesic to alleviate the postoperative pain may result in substantial analgesia and enhanced patient satisfaction. The benefits are often challenging to decipher in terms of cost reduction and necessity to improve quality of care. Furthermore, commonly used mediations like non–steroidal anti–inflammatory drugs (NSAIDs) and opioids are associated with potentially adverse side effects. The recent release of intravenous (IV) acetaminophen in the United States has raised concerns related to its analgesic efficiency and cost–effectiveness. The aim of this retrospective chart review is to study the perioperative use of IV acetaminophen and its potential for cost effectiveness when used in this setting.

Methods: We performed a retrospective cohort study of all patients who had undergone surgeries at Drexel University College of Medicine⁄Hahnemann University hospital from September 2011 to February 2012. This review evaluated cost of IV acetaminophen per patient, cost of other analgesics (NSAIDs, Opioids) and total cost of analgesics used per patient. In addition, we evaluated visual analog scores (VAS), length of hospital stay, global patient satisfaction, and opioid related side–effect. The groups were compared with Chisquared test and p–values were reported.

Results: Analysis of the retrospective data showed that the majority of the study population had were ASA grade II (51%) and 74% of the patients received acetaminophen as an preoperative analgesic. All patients, 80 (100%) received intraoperative analgesics which included a combination of drugs such as fentanyl, morphine and hydromorphone. In addition, postoperatively, 36 (45%) did not receive analgesia and 19 (24%) had regional anesthetic nerve blocks. Seventy one (88%) of patients did not have any adverse events; post–operative nausea was noticed in 5 (6.25%) patients and vomiting in 1 (1.25%) of patients.

Conclusion: This retrospective pharmacoeconomic review suggests that the IV formulation of acetaminophen increased the total cost of analgesics used perioperatively. Although, it may be cost effective since there is a less total opioid consumption and subsequently fewer opioid related side effects and potentially decreased length of stay. Further complete randomized controlled studies are needed to delineate the role and cost effectiveness of multimodal analgesia with the use of IV acetaminophen.

Keywords: Cost; Acetaminophen; Efficacy; Outcomes; Surgery; Postoperative

## Introduction

Intravenous acetaminophen is an analgesic and antipyretic agent that has been recommended worldwide as a first–line agent for the control of pain and fever in adults and children. While oral and rectal acetaminophen has been on the market for many decades, IV acetaminophen was introduced only about 10 years ago in Europe and 2 years ago in the United States. The key advantage of IV acetaminophen is that approximeately 1 gram is associated with about twice the plasma and effective site concentrations compared to 1 gram of its oral or rectal formulations. The higher concentrations lead to greater central nervous system penetration which is consistent with the superior analgesic efficacy seen with IV compared with oral acetaminophen in the surgical setting [1]. Pharmacoeconomic data are particularly useful for new drug reviews, where branded pharmaceuticals were mostly responsible for the 200% increase in prescription drug costs from 1990 through 2000 [2]. Analgesia is one potential challenge—use of a potent analgesic to reduce postoperative pain may result in significant analgesia and improved patient satisfaction, but it is difficult to translate these effects in figures of cost reduction or improvements in efficiency. In fact, the opposite may be true because the most common classes of analgesics used in the hospital— specifically, nonsteroidal anti–inflammatory drugs (NSAIDs) and opioids—are associated with significant adverse drug reactions which could pose a significant additional economic burden. Since 2005, various studies have been carried out to know the effectiveness of potentially costly adverse drug events (ADEs) [2] of intravenous acetaminophen. These studies clearly establish the analgesic efficacy of intravenous acetaminophen as well as the safety profile of this drug, and also help to decrease the requirements of other analgesics for pain control [3,4]. In double–blind clinical trials, single or multiple doses of intravenous acetaminophen, 1 gram generally provided significantly better analgesic efficacy than placebo treatment in adult patients who had undergone dental, orthopedic or gynecological surgeries [5–8]. Furthermore, where evaluated, intravenous acetaminophen 1 gram generally reduced need for opioid rescue medication [9]. The intravenous route is especially advantageous in postsurgical situations when oral (e.g. infections with severe fever or vomiting) or rectal (e.g. high variability in uptake and bioavailability) routes are not suitable or effective [6]. IV acetaminophen is a costly drug and 1gram vial costs $10 as compared to 1 gram oral that costs$0.80. Though the efficacy and safety of this drug has been established by the recent studies, none of the studies have tried to know the cost effectiveness of this drug.

In our study, we performed a retrospective chart review and pharmcoeconomic analysis of patients that were given perioperative IV acetaminophen. The recent release of IV acetaminophen in the United States has anesthesiologists, surgeons, and facilities questioning the analgesic and cost–effectiveness of intravenous acetaminophen perioperative use in regard to pain relief, opioid utilization, and Post Anesthesia Care Unit (PACU) discharge times. The objective of this study is to determine the cost effectiveness of perioperative use of IV acetaminophen in various surgical procedures compared to other analgesics such as NSAIDs and opioids.

## Methods

We conducted a retrospective cohort study evaluating costs of IV acetaminophen per patient, cost of other analgesics (Opioids, NSAIDs, etc.) per patient, and total cost of analgesics used per patient. In addition, we reviewed, visual analog scores (pre and postoperative), length of hospital stay, global patient satisfaction, opioid related side–effects (e.g. nausea, vomiting, changes in blood pressure, delirium). The Drexel University Institutional Review Board approval was obtained prior to patient selection. Patients who had surgery and received IV acetaminophen between September 2011 to February 2012 were selected from the operating room (OR) pharmacy list and schedule. Furthermore, patient's medical history, type of surgery, duration of surgery, hospital stay, medications,substance abuse, ASA status, pre and post–operative pain scores, use of analgesics, complications, name of surgeon, anesthesiologist and CRNA and patient satisfaction, if documented, were collected from the medical record.

## Inclusion and exclusion critieria

The following were the inclusion criteria for individuals into the study: 16– 65 years of age, males and females, ASA physical status I, II, or III, undergone surgical procedure, availability of medical charts, documentation of pain scores. The following were the exclusion criteria for individuals into the study: history of substance abuse, history of chronic pain greater than three months, nondocumentation of pain scores, pregnancy, impaired liver function, psychiatric disorder.

## Statistical analysis

No sample size or power calculation was performed, all eligible patients who had undergone surgery at Drexel University College of Medicine⁄Hahnemann University Hospital from September 2011 to February 2012 were included in this study. An estimation of 100 medical charts was reviewed and 80 patients met the eligibility criteria. Data analysis was performed with SPSS (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp). Mean, standard deviation (SD), median and range were obtained for age, length of hospital stay, length of PACU stay and VAS. Number of observations and percentages were obtained for type of surgery, ASA status, administration of analgesics and regional blocks, and adverse events. The groups were compared with Chisquared test and p–values were reported.

## Results

The analysis included data from 80 patients who underwent surgeries at Drexel University College of Medicine⁄Hahnemann University Hospital from September 2011 to February 2012. Results showed that there were 76 (95%) orthopedic surgeries and 4 (5%) plastic surgeries included in the study. The patient demographics and adverse events are presented in Table 1. The mean age was 47 years old (standard deviation 15). The mean postoperative VAS was 5 (standard deviation 4). Length of stay in the PACU and the hospital were similar with a mean of 3 days (standard deviation2). Forty one (51%) of the study population had an ASA of II. Fifty nine (74%) of patients received IV acetaminophen for pain control. Thirty six (45%) of patients did not receive postoperative analgesics; 19(24%) patients had regional blocks. Seventy–one(88%) of patients did not have any adverse events; postoperative nausea occurred in 5 (6.25%) of patients and vomiting occurred in 1(1.25%) of patients. The average pain score was 5, (standard deviation 4) for the acetaminophen group, the mean was 8 (standard deviation 3) for the ibuprofen group and the mean was 4 (standard deviation 5) for combination of both groups (Figure 1 and Table 2). The cost of 1000 mg IV acetaminophen is $12 as opposed to$0.80 for 1000 mg oral acetaminophen. The cost of 800 mg IV Ibuprofen is $11. The cost of PCA Hydromorphone 1mg/ml 30 ml cartridge is$20.49 and PCA Morphine 5 mg⁄ml 30 ml cartridge is \$7.90 (Table 3).