Oral Morphine Equivalent

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Description

This phenotype takes the opioid medications given for a case and converts them into oral morphine equivalents, expressed in milligrams oral morphine. This phenotype also returns whether an opioid medication was documented as given but was not included in the OME for the case due to lack of dosing information (labeled as "unknown"). For example, if 10mg IV morphine was recorded and an unknown dose of IV fentanyl, the case would return the OME for the morphine and "unknown" as a 1, indicating another opioid medication was given and not included in the OME calculation. Additionally, this phenotype returns whether Remifentanyl was included as the current OME converion used is 0.

Limitation

For intraoperative medications documented without dosing parameters we note there was a medication given for which we could not convert to OME, labeled as "unknown". Not all listed medications are found in the MPOG data, as some medications listed in the table are not used in the perioperative setting. Additionally, this phenotype calculated intraoperative OME without consideration of the patient's home medications or the patient's preoperative opioid tolerance. Documentation errors for medications occur in medical records. We have found that OME values >600 typically contain a documentation error and should be considered in error for any given case.

Data quality is limited to individual site documentation accuracy, completeness, and variable mapping, which is performed by each site, independently. MPOG, as the coordinating center, reviews data quality at each data upload and monthly via Data Diagnostics and Case Validation tools. This review, while thorough, may not contain all data elements relevant to this phenotype and thus should be carefully reviewed by the user.

Value Type

Numeric

Enumeration

Value	Value Code	Definition

Return Columns

Column Name	Data Type

Granularity

Logic

This collation returns the following columns:

- a single value for OME per case

- unknown dose - yes (1) / no (0) - an indicator for opioids that were unable to calculate OME value as data was missing to calculate dose given

- REMI - yes (1) / no (0) - an indicator whether remifentanil was used in the case

All medications for each case are gathered and converted to mg for their doses administered. Then these medications are converted to oral morphine (mg) using the following conversions:

Oral Morphine Equivalance Table
Opioid	Route	Equivalence (mg)	Potency	Source	Comment
Morphine	Oral	30	1	APS/CDC
MS Contin (controlled release Morphine)	Oral	30	1	https://www.healthcare.uiowa.edu/familymedicine/fpinfo/Docs/adultopioidrefguide.htm
Codeine	Oral	200	0.15	APS/CDC
Hydromorphone (Dilaudid)	Oral	7.5	4	APS/CDC
Hydrocodone	Oral	30	1	CDC
Oxycodone	Oral	20	1.50	APS/CDC
Oxymorphone	Oral	10	3	APS/CDC
Meperidine	Oral	300	0.10	APS
Tramadol	Oral	300	0.10	CDC
Fentanyl	transdermal (mcg/hr)	25-300 ug/hr	2.40	CDC	*note this figure varies significantly based on resource. For consistency we stuck with CDC recommendations.
Methadone	Oral	1-20 mg/day	4	CDC	** Walker et al found 1:4.7 ratio in a study of 29 patient. Important that below numbers not be used for equianalgesic conversion
Methadone	Oral	21-40 mg/d	8	CDC
Methadone	Oral	41-60 mg/day	10	CDC
Methadone	Oral	>61-80 mg/d	12	CDC
Buprenorphine (Suboxone)	Sublingual	75	0.40	Other	Either exclude from inclusion or flag OME result with "includes buprenorphine". Demystifying Opioid Conversion Calculations - Mary Lynn McPherson


IV Morphine Equivalance Table
Opioid		Equivalence (mg)	Potency	Source	Comment (from Epic Review)
Morphine	IV	10	1	APS
Codeine	IV	100	0.10	APS
Fentanyl	IV	0.10	100	APS
Fentanyl	epidural	0.033	300	Open Anesthesia
Fentanyl	IT	0.011	900	Open Anesthesia
Hydromorphone (Dilaudid)	IV	1.50	6.67	APS
Hydromorphone (Dilaudid)	epidural	0.30	33.33	Open Anesthesia
Hydromorphone (Dilaudid)	IT	0.06	166.67	Open Anesthesia
Oxymorphone	IV	1	10	APS	From UpToDate; Cancer pain management with opioids: Optimizing analgesia
Meperidine	IV	100	0.10	APS
Meperidine	IT	0.10	100
Tramadol	IV	100	0.30	APS
Buprenorphine (Suboxone)	IV	0.40	25	APS
Nalbuphine	IV	10	1	APS
Butorphanol	IV	2	5	APS
Morphine	IT	0.10	100	Krames / OpenAnesthesia	Morphine: 10mg IV = 1mg Epidural = 0.1mg Intrathecal (1/10 ratio; very hydrophilic)
Morphine	epidural	1	10	Krames
Sufentanil	IV	0.02	500	Anderson	*not a concensus. Sufenta is 2.5x to 24x more potent than fent. Most likely 2.5-10x more potent
Sufentanil	epidural	0.0067	1500	5x epidural fentanyl
Sufentanil	IT	0.0025	3960	4.4x IT fentanyl
Alfentanil	IV	0.50	60
Remifentanil	IV	0	0
Methadone	IV	IV:PO -->1:2	2	MLM	convert to PO methadone then to OME

Sources
APS	APS Principles of Analgesic Use 7th ed. Table 2 p. 27-36
CDC	CDC guidelines for prescribing opioids for chronic pain 2016
MLM	Mary Lynn McPherson - Demystifying opioid conversion calculations, ch 6 p. 134, 2010.
Krames	Intrathecal Infusional Theraipes for intractible pain: patient management guidelines. J Pain Symptom Manage 1993;8:36-46.
Anderson	Anderson R, Saiers JH, Abram S, et al. Accuracy in equianalgesic dosing. conversion dilemmas. J Pain Symptom Manage. 2001;21(5):397-406. PMID 11369161.