Health Costs

How We Calculate Episodes of Care

Bundled Episodes

In most cases, CompareMaine reports the average costs for a single procedure, which may include both a professional and a facility component. However, for several procedures reported on CompareMaine, we use Optum’s Symmetry® Episode Treatment Groups® (ETG) grouper to develop episodes of care.

The ETG software is an illness classification tool that groups medical and pharmacy claims data into episodes of care – a set of services provided to treat a clinical condition or procedure (often referred to as a bundled payment). Although pharmacy claim lines are considered in the tool, only medical claims are used as part of the payment calculations on CompareMaine.

Of the 18 bundled episodes, 3 colonoscopy procedures (indicated with an asterisk* in the list below) are restricted to outpatient encounters; the remaining 15 bundled episodes may be inpatient or outpatient encounters.

  • Biopsy of prostate gland
  • Carpal tunnel release surgery
  • Catheter insertion of stents in major coronary artery or branch, accessed through the skin
  • C-section (Cesarean delivery)
  • Colonoscopy with biopsy for noncancerous growth*
  • Colonoscopy without biopsy for encounter for preventative health services*
  • Colonoscopy with removal of polyps or growths using an endoscope*
  • Gallbladder removal
  • Hip replacement
  • Insertion of catheter for imaging of heart blood vessels or grafts
  • Knee replacement
  • Repair of groin hernia patient age 5 years or older
  • Removal of tonsils and adenoid glands patient younger than age 12
  • Surgical arthroscopy of knee
  • Surgical arthroscopy of shoulder
  • Upper gastrointestinal (GI) endoscopy without biopsy
  • Upper gastrointestinal (GI) endoscopy with biopsy
  • Vaginal delivery

For reference, in the list above, * indicates procedure is restricted to outpatient encounters, and indicates procedure is limited to the day of the procedure.

Many of the surgical procedures reported on CompareMaine include the CPT code for the primary procedure plus all related procedure or service codes that took place 30 days prior and 30 days after the primary procedure. For example, a C-section may include the costs of ultrasounds, doctor appointments, blood work, surgeon fees, medications used before, during, and after surgery (like an epidural), a hospital stay, and follow-up appointments. Note: Those surgical procedures reported on CompareMaine that are limited to the day of the procedure are indicated with a plus sign † in the list above.

One of the primary differences between the ETG and MHDO’s custom logic for single services or procedures, is the ETG does not require that every episode include the same set of codes and services, whereas MHDO’s logic requires a specific set of codes and services.


The ETG grouper measures the severity of each episode based on regression models that were developed using a nationally representative sample of 66 million episodes. These severity models consider complications and comorbidities associated with each ETG base, along with demographics, such as age and gender, and assign weights to each of these factors. The severity score is the sum of all the weights in the episode and a measure of expected, not actual, resource costs. This normalized measure indicates the average expected resource costs in comparisons to other episodes with the same ETG base.

In addition to severity score, each episode also has a severity level. The severity level is determined by the episode’s severity score and predetermined ranges for each level for an ETG base. Each ETG base can have up to four severity levels, with a score of one representing the lowest level of risk and four representing the highest. The severity level reflects the clinical reality of each ETG base.

Over 80% of the episodes included in the development of the payment estimates on CompareMaine 10.0 have a severity level of 1 and 6% have a severity level of 3 or above. Since the median is used to calculate the estimated average cost on CompareMaine, a severity level of one is typically used to produce the estimates.

To ensure that only relevant services are included in the creation of the episode and then reflected in the median payment estimates we use the following methodology:

  1. The claims data is processed by the ETG software and episodes are built from the CPT codes that appear on the claim lines and are associated with the ETG base, or the condition and location on the body.
  2. Only episodes with the proper ETG base code are selected. Services received at the same time but not associated with the bundled episode, as determined by the grouper, are not grouped into the episode.
  3. The episode is not included in the calculation of median payments if the grouper does not categorize the episode into an ETG category, trigger CPT codes are missing (CPT codes on the list of codes included in the cost calculations for a bundled episode), or treatment indicator codes exist that are unrelated to the procedure of interest.

The median payments are calculated using MHDO’s custom logic and consider all eligible episodes, regardless of severity. However, since we use the median to calculate the average cost and the median episode tends to be the most common type, the episode typically has no complications and minimal severity.