Dose Era

A Dose Era is defined as a span of time when the Person is assumed to be exposed to a constant dose of a specific active ingredient.

Field	Required	Type	FK Table	Description
dose_era_id	Yes	bigint		A unique identifier for each Dose Era.
person_id	Yes	bigint	PERSON	A foreign key identifier to the Person who is subjected to the Drug during the Dose Era. The demographic details of that Person are stored in the PERSON table.
drug_concept_id	Yes	bigint	CONCEPT	A foreign key that refers to a Standard Concept identifier in the Standardized Vocabularies for the active Ingredient Concept.
unit_concept_id	Yes	bigint	CONCEPT	A foreign key that refers to a Standard Concept identifier in the Standardized Vocabularies for the unit concept.
dose_value	Yes	numeric/float		The numeric value of the dose.
dose_era_start_date	Yes	date		The start date for the Dose Era constructed from the individual instances of Drug Exposures. It is the start date of the very first chronologically recorded instance of utilization of a drug.
dose_era_end_date	Yes	date		The end date for the Dose Era constructed from the individual instances of Drug Exposures. It is the end date of the final continuously recorded instance of utilization of a drug.

Conventions

• Dose Eras will be derived from records in the DRUG_EXPOSURE table and the Dose information from the DRUG_STRENGTH table using a standardized algorithm.
• Each Dose Era corresponds to one or many Drug Exposures that form a continuous interval and contain the same Drug Ingredient (active compound) at the same effective daily dose.
• Dose Form information is not taken into account. So, if the patient changes between different formulations, or different manufacturers with the same formulation, the Dose Era is still spanning the entire time of exposure to the Ingredient.
• The daily dose is calculated for each DRUG_EXPOSURE record by calculating the total dose of the record and dividing by the duration.

• The total dose of a DRUG_EXPOSURE record is calculated with the help of the DRUG_STRENGTH table containing the dosage information for each drug as following:

  1. Tablets and other fixed amount formulations

     Example: Acetaminophen (Paracetamol) 500 mg, 20 tablets.

     Data item	Stored value
     DRUG_STRENGTH	The denominator_unit is empty.
     DRUG_EXPOSURE	The quantity refers to number of pieces, e.g. tablets.
     	In the example: 20.
     Ingredient dose	= quantity x amount_value [amount_unit_concept_id]
     	Acetaminophen dose = 20 x 500mg = 10,000mg

  2. Puffs of an inhaler

     Note: There is no difference to use case 1 besides that the DRUG_STRENGTH table may put {actuat} in the denominator unit. In this case the strength is provided in the numerator.

     Data item	Stored value
     DRUG_STRENGTH	The denominator_unit is {actuat} .
     DRUG_EXPOSURE	The quantity refers to the number of pieces, e.g. puffs.
     Ingredient dose	= quantity x numerator_value [numerator_unit_concept_id]

  3. Quantified Drugs which are formulated as a concentration

     Example: The Clinical Drug is Acetaminophen 250 mg/mL in a 5mL oral suspension. The Quantified Clinical Drug would have 1250 mg / 5 ml in the DRUG_STRENGTH table. Two suspensions are dispensed.

     Data item	Stored value
     DRUG_STRENGTH	The denominator_unit is either mg or mL. The denominator_value might be different from 1.
     DRUG_EXPOSURE	The quantity refers to a fraction or, multiple of the pack.
     	In the example: 2
     Ingredient dose	= quantity x numerator_value [numerator_unit_concept_id]
     	Acetaminophen dose = 2 x 1250mg = 2500mg

  4. Drugs with the total amount provided in quantity, e.g. chemotherapeutics

     Example: 42799258 “Benzyl Alcohol 0.1 ML/ML / Pramoxine hydrochloride 0.01 MG/MG Topical Gel” dispensed in a 1.25oz pack.

     Data item	Stored value
     DRUG_STRENGTH	The denominator_unit is either mg or mL.
     	In the example: Benzyl Alcohol in mL and Pramoxine hydrochloride in mg
     DRUG_EXPOSURE	The quantity refers to mL or g.
     	In the example: 1.25 x 30 (conversion factor oz -> mL) = 37
     Ingredient dose	= quantity x numerator_value [numerator_unit_concept_id]
     	Benzyl Alcohol dose = 37 x 0.1mL = 3.7mL
     	Pramoxine hydrochloride dose = 37 x 0.01mg x 1000 = 370mg

     Note: The analytical side should check the denominator in the DRUG_STRENGTH table. As mg is used for the second ingredient the factor 1000 will be applied to convert between g and mg.

  5. Compounded drugs

     Example: Ibuprofen 20%/Piroxicam 1% Cream, 30ml in 5ml tubes.

     Data item	Stored value
     DRUG_STRENGTH	We need entries for the ingredients of Ibuprofen and Piroxicam, probably with an amount_value of 1 and a unit of mg.
     DRUG_EXPOSURE	The quantity refers to the total amount of the compound. Use one record in the DRUG_EXPOSURE table for each compound.
     	In the example: 20% Ibuprofen of 30ml = 6mL, 1% Piroxicam of 30ml = 0.3mL
     Ingredient dose	Depends on the drugs involved: One of the use cases above.
     	Ibuprofen dose = 6 x 1mg x 1000 = 6000mg
     	Piroxicam dose = 0.3 x 1mg x 1000 = 300mg

     Note: The analytical side determines that the denominator for both ingredients in the DRUG_STRENGTH table is mg and applies the factor 1000 to convert between mL/g and mg.

  6. Drugs with the active ingredient released over time, e.g. patches

     Example: Ethinyl Estradiol 0.000833 MG/HR / norelgestromin 0.00625 MG/HR Weekly Transdermal Patch

     Data item	Stored value
     DRUG_STRENGTH	The denominator units refer to hour.
     	In the example: Ethinyl Estradiol 0.000833 mg/h / norelgestromin 0.00625 mg/h
     DRUG_EXPOSURE	The quantity refers to the number of pieces.
     	In the example: 1 patch
     Ingredient rate	= numerator_value [numerator_unit_concept_id]
     	Ethinyl Estradiol rate = 0.000833 mg/h
     	norelgestromin rate = 0.00625 mg/h

     Note: This can be converted to a daily dosage by multiplying it with 24. (Assuming 1 patch at a time for at least 24 hours).