Risk of Hematoma After Ketorolac Use in Reduction Mammoplasty.
Condition: Breast Reduction; Reduction Mammoplasty; Hematoma; Hemorrhage
MeSH terms: Hemorrhage; Hematoma
Study type: Observational

Summary: 
      The investigators hope to answer the question, "does ketorolac increase the risk of hematoma
      after reduction mammoplasty?" using a case-control study. All patients who developed a
      hematoma post reduction mammoplasty (cases) at our institution, and match these with women
      who had an uncomplicated reduction mammoplasty (controls), and then compare frequency of
      ketorolac exposure between these two groups as the primary outcome. If ketorolac increases
      the risk of hematoma, one should expect cases to have been exposed to ketorolac more
      frequently than controls. Based on previously existing literature, the investigators
      hypothesize that cases and controls will not differ in their ketorolac exposure, that is,
      ketorolac does not increase the risk of hematoma.
    

Detailed description: 
      The electronic health record databases of St. Joseph's Healthcare Hamilton and Hamilton
      Health Sciences will be searched, using the coding system, for all cases of reduction
      mammoplasty with post--operative hematoma as a complication. Only hematomas which required
      return to the operating room for evacuation will be included (i.e. those treated with
      observation or needle aspiration will be excluded).

      Cases are defined as patients suffering a hematoma post reduction mammoplasty will be
      identified through hospital coding, and matched with controls based on the following
      criteria: age, body mass index (BMI), pre-existing hypertension, and institution. Controls
      are defined as patients who had uncomplicated reduction mammoplasty, and will be randomly
      pulled through retrospective chart review within the same databases, in the same time period
      (±5 years).

      All patient data will be de--identified, and all devices containing patient information will
      remain on hospital grounds, and be encrypted according to our hospital protocols. The
      following data will be extracted from patient charts: age, date of surgery, body mass index,
      surgeon, anesthetist, volume of breast tissue removed per breast, comorbidities, platelet
      count, coagulation profile, ketorolac and opioid use including dose, timing, frequency,
      duration, and route of administration of both, time to discharge including length of stay if
      overnight, comorbidities (including smoking status), American Society of Anesthesiology
      score, and post--operative usage of drains.

      Matching of cases and controls will be performed by the primary investigator (JB), and at the
      time of matching, the only visible patient information will be the de-identified patient
      identification (ID) and the four matching variables (ketorolac exposure was not visible).

      The frequency of ketorolac exposure between cases and controls will then be reviewed, and the
      odds ratio (OR) of exposure to ketorolac, with 95% confidence intervals will be calculated. A
      two by two table will be generated from our data. Since the incidence of hematoma formation
      after reduction mammoplasty is very low, the odds ratio will closely approximate the relative
      risk. To evaluate the statistical significance of the ORs, a level of significance of 0.05
      will be used. Independent samples t-test will be used to compare continuous demographic data,
      and Chi-square analysis will be used for ordinal or categorical data between cases and
      controls.

      Sample size was calculated using the POWER program, described by Dupont and Plummer in 1990.
      A sample size of 25 cases matched with 25 controls (total n = 50) was required from the
      following data:

        -  p0 = 0.32 (approximate rate of ketorolac exposure amongst breast reduction patients from
           previous literature from Cawthorn et al.)

        -  α = 0.05 (chance of type I error)

        -  P = 0.8 (power)

        -  m = 1 (matching ratio1:1)

        -  Ψ = 3.6 (estimated risk ratio of developing hematoma post breast reduction if exposed to
           ketorolac, Cawthorn et al.)

        -  Φ = 0.2 (measurable difference)
    

Intervention name(s): Hematoma
Intervention type(s): Procedure
Intervention description(s): Hematoma requiring return to operating room.
Observational model: Case-Control
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Medical coders will identify all possible cases of hematoma by searching the key words
        "hemorrhage," "hematoma," and "plastic surgery". Hematomas post reduction mammoplasty will
        be manually retrieved and reviewed. Control patients will be randomly pulled from the
        database of uncomplicated reduction mammoplasties.
      
Keywords: Breast reduction; Reduction mammoplasty; Hematoma; Hemorrhage; Ketorolac; Toradol