A Trial of the Cost Effectiveness of IV Acetaminophen in Bariatric Surgery
Condition: Hospital Costs; Length of Stay; Postoperative Pain Score; Patient Satisfaction
MeSH terms: Pain, Postoperative
Study type: Interventional
Phase: Phase 4

Summary: 
      Bariatric surgery is the only proven and effective long term treatment for morbid obesity. In
      an attempt to reduce patients' post-operative hospital stay, lower associated health care
      costs, and improve satisfaction scores, St Luke's University Health Network (SLUHN) recently
      adopted a fast track bariatric surgery (FTBS) protocol. Findings to date show that FTBS is
      safe and effective when performed in a Center of Excellence (COE) such as ours. However,
      post-operative pain control remains a challenging issue, with only intravenous (IV) or PO (by
      mouth) narcotics appropriate for bariatric surgery patients.

      IV acetaminophen, which has been used successfully in Europe, was recently approved by the
      Federal Drug Administration (FDA) for use in the US. However, no data exist regarding the use
      of IV acetaminophen in bariatric surgery patients, nor are there any data assessing its cost
      effectiveness. Therefore, our study will investigate the economic impact of administering IV
      acetaminophen to bariatric surgery patients, as well as its effect on clinical outcomes such
      as patients' post-operative length of stay, self-reported pain, readmissions, emergency room
      (ER) visits and complications.

      The study design will be a randomized, double-blind, parallel-group, controlled trial in a
      single bariatric Center of Excellence (COE) that is part of the St. Luke's University Health
      Network (SLUHN). Patients will consist of up to 200 morbidly obese adult bariatric surgery
      candidates > 18 years of age undergoing either laparoscopic Roux-en-Y Gastric Bypass (LRYGB)
      or laparoscopic Sleeve Gastrectomy (LSG). Group 1 (treatment) will receive IV acetaminophen
      plus IV narcotics for the first 6 hours post-surgery followed by IV/ PO narcotics for the
      remaining 18 hours. Group 2 (control) will receive IV normal saline plus IV narcotics for the
      first 6 hours post-surgery followed by IV/PO narcotics for the remaining 18 hours. Data
      analysis will include quantile regression, mixed randomized-repeated analysis of covariance
      (ANCOVA) and selected univariate comparisons, with p < .05 denoting statistical significance
      for all outcomes.
    

Detailed description: 
      This was a double-blind, prospective, randomized controlled trial conducted at a single
      accredited bariatric center that is part of a multi-campus university teaching hospital. The
      Institutional Review Board approved the study.

      We hypothesized that administering IV acetaminophen plus IV narcotics/PO narcotics to
      bariatric patients will produce significant cost savings to our hospital network, as well as
      result in lower self-reported pain from baseline to 24 hours post-surgery; a decrease in
      hospital length of stay (LOS) to < 24 hours; and higher overall patient satisfaction compared
      to patients receiving IV narcotics plus normal saline as placebo.

      Based on the smallest clinically meaningful difference in mean pain scores of < 3 for the IV
      Acetaminophen group versus > 5 for the normal saline group (representing a minimum reduction
      of 40%), 24 patients are required to achieve 92% power at α = .05.

      To ensure an adequate number of complete data points, a decision was made to recruit a total
      of 100 patients. Inclusion and exclusion criteria are presented in table 1.

      Patients were randomly assigned to either treatment or control groups in a 1:1 ratio using
      permuted block sizes of 8.

      To preserve blinding of group assignment among the surgeons, patients, nurses and other team
      members, randomization numbers generated by the statistician were printed out and placed on
      the medication infusion bags by the pharmacist.

      Group 1 (treatment) received IV acetaminophen (1g in 100 ml of 0.9% normal saline IV Q 6hrs
      for 24 hours) plus IV narcotics (2-4 mg IV Q2hrs PRN) 30 minutes before surgery, followed by
      medication plus IV narcotics (2-4 mg IV Q2hrs PRN)/ PO narcotics (Oxycodone 5-10 ml PO Q4 hrs
      PRN) for the remaining 18 hours.

      Group 2 (control) received IV normal saline (100 ml of 0.9% normal saline IV Q 6hrs for 24
      hours) plus IV narcotics (2-4 mg IV Q2hrs PRN) 30 minutes before surgery, followed by saline
      plus IV narcotics (2-4 mg IV Q2hrs PRN)/ PO narcotics (Oxycodone 5-10 ml PO Q4 hrs PRN) for
      the remaining 18 hours.

      Pain was formally assessed every 2 hours for the first 24 hours post-surgery using a 10-point
      ordinal scale, with 0 representing no pain and 10 representing the worst pain. Rescue
      narcotics were given as needed depending on whether self-reported pain is moderate (4-6 on
      10-point pain scale) or severe (> 7 on 10-point pain scale).

      In the first 6 hours, patients were only offered IV narcotics. After the first 6 hours,
      patients were offered either IV or PO narcotics as deemed appropriate by the administering
      nurse based on the clinical condition and ability to tolerate PO intake. For moderate pain,
      patients received either IV morphine 2 mg IV Q2hrs PRN or PO Oxycodone 5 ml PO Q4hrs PRN. For
      severe pain, patients received either IV morphine 4 mg IV Q2hrs PRN or PO Oxycodone 10 ml PO
      Q4hrs PRN.

      Total hospital network costs for all relevant services were represented in dollar amounts as
      a continuous variable. Total costs included both direct and indirect costs. Direct costs were
      based on postoperative length of stay and the cost associated with acetaminophen and narcotic
      administration. Indirect costs included the cost of ER visits secondary to postoperative pain
      and also the performance of any radiographic studies postoperatively to evaluate for
      abdominal pain as deemed clinically necessary by the attending surgeon.

      Hospital length of stay (LOS) was dichotomized as < 24 hours and > 24 hours, given the
      expected relative infrequency of patients requiring a stay > 24 hours.

      Patients' self-reported satisfaction was assessed using a 5-point Likert scale (from strongly
      disagree to strongly agree) at 10 days to 2 weeks post-surgery (see Figure 1).

      Descriptive outcomes are reported as means and standard deviations for normally distributed
      continuous variables; medians and interquartile ranges for skewed continuous variables; and
      frequencies and percentages for categorical variables

      Primary outcomes included the following variables

      • Total hospital network direct costs (including direct cost per adjusted patient day and
      costs for IV acetaminophen, morphine and narcotics administration):

      The original data analysis plan called for quantile regression with the covariates of
      treatment group (IV acetaminophen plus narcotics versus IV narcotics plus normal saline) and
      surgery type (LRYGB versus LSG), based on the assumption that the direct cost data would be
      skewed with unequal variance across the distribution of sample group outcomes.

      However, preliminary inspection of the data revealed that basic assumptions of normality of
      sampling distributions, homogeneity of variance and absence of significantly influential
      outliers were met. Therefore, we conducted factorial randomized-groups analysis of variance
      (ANOVA) with the between-group factors of treatment group and surgery type, as well as the
      treatment group * surgery type interactional effect.

        -  Mean self-reported pain scores: mixed randomized-repeated measures analysis of
           covariance (ANCOVA) with the randomized factors of treatment group (IV acetaminophen
           plus narcotics versus IV narcotics plus normal saline) and surgery type (LRYGB versus
           LSG); the repeated measures factor of pain scores over time (i.e., 2-hours intervals
           from 2 to 22 hours); and the first post-operative pain scale assessment as the
           covariate. Pain scores were measured on a numeric scale, with 0 representing no pain and
           10 representing the worst imaginable pain. Prior to data analysis, the assumptions of
           normality of sampling distributions, homogeneity of variance, presence of significantly
           influential outliers, linearity between the baseline pain score covariate and subsequent
           pain scores, and homogeneity of regression for the covariate-outcomes slopes were
           evaluated. These assumptions were met with the exception of moderate heterogeneity of
           variance for the IV acetaminophen-LSG group for 10-hour pain scores and largely
           curvilinear relationships between the covariate and subsequent pain scores. Therefore,
           the covariate was logarithmically transformed, and a more conservative p-value < .025
           was used to assess pain scores over time. In order to obtain a clearer understanding of
           the repeated measures main effect of pain scores over time, an additional analysis of
           variance excluding the covariate of baseline pain scores was also conducted.

        -  Length of stay (< 24 hours versus > 24 hours): Cochran-Mantel-Haenszel test for
           treatment group with surgery type as the stratification variable.

        -  Patient satisfaction: a patient satisfaction survey was given to all the patients in our
           study to fill during their first postoperative visit between Post-Operative Day (POD) #7
           and POD# 10. The questionnaires are filled by the patients and collected by our study
           coordinator for analysis before the patient is examined by the surgeon to avoid any bias
           in reporting satisfaction scores. Separate Mann Whitney rank sums tests by treatment
           group and surgery type

        -  Patient rating of overall pain: pain overall score (0-10) was also collected during the
           first postoperative visit between POD#7 and POD#10 factorial randomized-groups ANOVA by
           treatment group, surgery type and treatment group*surgery type interaction
    

Intervention name(s): Acetaminophen
Intervention type(s): Drug
Intervention description(s): Group 1 (treatment) will receive IV acetaminophen (intervention drug) (1g in 100 ml of 0.9% normal saline IV Q 6hrs for 24 hours) plus IV narcotics (2-4 mg IV Q2hrs PRN) for the first 6 hours post-surgery followed by IV narcotics (2-4 mg IV Q2hrs PRN)/ PO narcotics (Oxycodone 5-10 ml PO Q4 hrs PRN) for the remaining 18 hours.
Intervention MeSH terms: Acetaminophen
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Treatment
Keywords: Acetaminophen; Gastric Bypass; Sleeve Gastrectomy; Pain; Cost