eMediplan CHMED Implementation Guide
2.1.0 - CI Build Switzerland flag

eMediplan CHMED Implementation Guide, published by IG eMediplan. This is not an authorized publication; it is the continuous build for version 2.1.0). This version is based on the current content of https://github.com/ahdis/chmed/ and changes regularly. See the Directory of published versions

Dosage

The model of dosages between CHMED23A and the CHMED (FHIR version) differ sligthly due to the FHIR dosage model. This has an effect on how to map the different attributes form CHMED23A to CHMED.

Posology and Dosage

  • The CHMED23A model defines for a Medicament n Posologies. The posology of a medicament describes when, which quantity of the medicament must be applied. Different types of Posology objects can be specified to define different dosages.
  • In FHIR a MedicationStatement/MedicationRequest can have n Dosages with one Timing (which can have repeating timing defintions).

Example:

CHMED23A format for Posology:

{ 
	"DtFrom": "2021-10-07", // Taking must occur on this date (DtFrom and DtTo are equal) 
	"DtTo": "2021-10-07", 
	"RM": 1, // Before meal 
	"InRes": false, // The Medicament MUST be taken (not in reserve) 
	"PO": { 
		… // The posology object MUST specify the amount to be taken and CAN specify when 
	} 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "additionalInstruction" : [
        {
          "coding" : [
            {
              "system" : "http://snomed.info/sct",
              "code" : "307165006",
              "display" : "Before meal (qualifier value)"
            }
          ]
        }
      ],
      "timing" : {
        "repeat" : {
          "boundsPeriod" : {
            "start" : "2021-10-07",
            "end" : "2021-10-07"
          }
        }
      },
      "asNeededBoolean" : false
    }
  ]

CHMED Dosage:

  • Data Type Profile to define the FHIR representation of the dosage according tho the ‘Posology’ in CHMED23A.
  • Mapping to represent the relationship of FHIR to CHMED23A.

Relation to CH EMED

CAVE: This Posology element mapping shown above is limited compatible with the CH EMED dosage. In the Swiss exchange format, structured dosage (normal/split) is currently defined for the 1-1-1-1 scheme in addition to unstructured dosage for complex dosage.

  • In order to be able to map the scheme 1-1-1-1, the elements Dosage.timing.repeat.when and Dosage.doseAndRate are required in the structured dosage of CH EMED.
  • An important difference is the numbering of the Dosage.sequence element:
    • CH EMED: For the split dosage, the dosage sequences are numbered in ascending order (starting with 1).
    • CHMED: In order to be able to map the Posology Object Sequence as well, the element is defined as follows: The order of the dosage instructions (number is identical -> concurrent, number is different -> sequential)

Timing Event

The code for the time of adminstration has to come from the ValueSet EventTiming.
For the representation according to the 1-1-1-1 scheme, the values MORN-NOON-EVE-NIGHT from this ValueSet are highly recommended for the Swiss use (see also CH EMED).

Dose and Rate

The amount of medication administered is represented with SNOMED CT or UCUM codes, which are defined in the ValueSet UnitCode (see also CH EMED).
The mapping to CDTYP9 can be found in this ConceptMap.

Note for the following FHIR examples:
The CH EMED exchange format requires the structured specification of units when defining quantity and range. In CHMED23A is the Unit element (not always shown in the CHMED23A examples) on the same level as the Posology element and mandatory if Posology is defined.

Posology Objects

Different types of posology objects are specified in CHMED23A. Details and examples for the 6 types (Daily, FreeText, Single, Cyclic, Sequence, Even/odd days) are described in the following sections.

Daily

Describes when (morning, noon, evening, night) and how much of a medicament must be taken daily, using a simple structure.

Day segments
  1. Morning -> MORN
  2. Noon -> NOON
  3. Evening -> EVE
  4. Night -> NIGHT

In the exchange format CH EMED is with structured dosing the format 1-1-1-1, meaning the administration time in the morning, at noon, in the evening, at night, supported. An additional differentiation is made whether it is a normal or split dosing. For normal dosing, the dose quantity is the same at the defined administration times (e.g. 1-0-1-0, 1-0-1-0). For split dosing, the dose quantity varies depending on the administration time (e.g. 1-0-2-0, 2-1-2-0).

Example 1-0-1-0: Take daily 1 in the morning and 1 in the evening.

CHMED23A format for Daily:

{
	"T": 1, // Daily posology object 
	"Ds": [ 
		1.0, // 1 pill in the morning 
		0.0, 
		1.0, // 1 pill in the evening 
		0.0 
	] 
}

FHIR format for Dosage (structured normal) (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "1",
            "display" : "Daily"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "when" : [
            "MORN",
            "EVE"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Example 1-0-2-0: Take daily 1 in the morning and 2 in the evening.

CHMED23A format for Daily:

{
	"T": 1, // Daily posology object 
	"Ds": [ 
		1.0, // 1 pill in the morning 
		0.0, 
		2.0, // 2 pills in the evening 
		0.0 
	] 
}

FHIR format for Dosage (structured split) (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "1",
            "display" : "Daily"
          }
        }
      ],
      "sequence" : 0,
      "timing" : {
        "repeat" : {
          "when" : [
            "MORN"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    },
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "1",
            "display" : "Daily"
          }
        }
      ],
      "sequence" : 0,
      "timing" : {
        "repeat" : {
          "when" : [
            "EVE"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 2.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Free Text

Describes an unstructured posology consisting of free text.

In the exchange format CH EMED, the dosage is given as free text for the unstructured form.

Example: Free text.

CHMED23A format for Free Text:

{ 
	"T": 2, // Free text posology object 
	"Text": "Take one pill. Wait one hour. If symptoms persist, take a second pill and wait 30 minutes. If symptoms persist, contact doctor." // Free text 
}

FHIR format for Dosage (non-structured) (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "2",
            "display" : "FreeText"
          }
        }
      ],
      "text" : "Take one pill. Wait one hour. If symptoms persist, take a second pill and wait 30 minutes. If symptoms persist, contact doctor."
    }
  ]

Single

Describes a single application of a medicament. With the single field being a timing object, there are several possibilities to specify when the single application takes place.

Example: Take 1.

CHMED23A format for Single:

{ 
	"T": 3, // Single taking posology object 
	"TD": { 
		"T": 1, // Dosage only timed dosage 
		"D": { 
			"T": 1, // Amount dosage type 
			"A": 1.0 // Amount of 1 
		} 
	} 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "3",
            "display" : "Single"
          }
        },
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "1",
            "display" : "DosageOnly"
          }
        }
      ],
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Cyclic

Describes the application of a medicament at constant intervals.

Time units
  1. Second -> s
  2. Minute -> min
  3. Hour -> h
  4. Day -> d
  5. Week -> wk
  6. Month -> mo
  7. Year -> a

Example: 1 pill twice a week.

CHMED23A format for Cyclic:

{ 
	"T": 4, // Cyclic posology object 
	"CyDuU": 5, // weekly duration unit 
	"CyDu": 1, // 1 (week) 
	"TD": { 
		"T": 1, // Doasage only 
		"D": { 
			"T": 1, // Dosage only 
			"A": 1.0 // Amount = 1 (pill) 
		} 
	}, 
	"TDpC": 2 // take it twice within cycle 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "4",
            "display" : "Cyclic"
          }
        },
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "1",
            "display" : "DosageOnly"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "frequency" : 2,
          "period" : 1,
          "periodUnit" : "wk"
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Sequence

Allows to combine multiple posologies with a pause as a sequence.

CAVE:
The FHIR mapping of the ‘duration (incl. duration unit)’ is in the Dosage.timing.repeat.count element from data type positiveInt. In FHIR it is therefore represented how often the defined timing element is to occur. The mapping of another unit of the duration of the sequence is therefore not possible.

Example: Take daily 1 for 21 days, then take a break of 7 days.

CHMED23A format for Sequence:

{ 
	"Meds": [ 
		{ 
			"Id": "Med1", 
			"Ps": [ 
				{ 
					"PO": { 
						"T": 5, // Sequence posology object 
						"SOs": [ 
							{ 
								"T": 1, // Posology sequence sequence object 
								"PO": { 
									"T": 4, // Cyclic posology object
									"CyDuU": 4, // Daily cycle duration unit 
									"CyDu": 1, // Take every 1 (day) 
									"TD": { 
										"T": 1, // Dosage only timed dosage 
										"D": { 
											"T": 1, // Simple dosage 
											"A": 1.0 // 1 (pill) 
										} 
									}, 
									"TDpC": 1 // take it once within cycle
								}, 
								"DuU": 4, // Daily duration unit for the sequence 
								"Du": 21 // Duration of 21 (days) for the sequence 
							}, 
							{ 
								"T": 2, // Pause sequence object 
								"DuU": 4, // Daily duration unit for the sequence 
								"Du": 7 // Duration of 7 (days) for the pause 
							} 
						] 
					} 
				} 
			], 
			"U": "TABL" // Quantity unit
		} 
	] 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "5",
            "display" : "Sequence"
          }
        },
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "4",
            "display" : "Cyclic"
          }
        },
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "1",
            "display" : "DosageOnly"
          }
        }
      ],
      "sequence" : 0,
      "timing" : {
        "repeat" : {
          "count" : 21,
          "frequency" : 1,
          "period" : 1,
          "periodUnit" : "d"
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Tablet (unit of presentation)",
            "system" : "http://snomed.info/sct",
            "code" : "732936001"
          }
        }
      ]
    },
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "5",
            "display" : "Sequence"
          }
        }
      ],
      "sequence" : 1,
      "timing" : {
        "repeat" : {
          "count" : 7,
          "frequency" : 1,
          "period" : 1,
          "periodUnit" : "d"
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 0.0,
            "unit" : "Tablet (unit of presentation)",
            "system" : "http://snomed.info/sct",
            "code" : "732936001"
          }
        }
      ]
    }
  ]

Even/Odd Days

Allows to specify a posology that must be applied on even or odd days.

Example: Take 1 on even days, starting 02.01.2021.

CHMED23A format for Even/Odd days:

{ 
	"Meds": [ 
		{ 
			"Id": "Med1", 
			"Ps": [ 
				{ 
					"DtFrom": "2021-01-02", // Posology start 
					"PO": { 
						"T": 6, // EvenOddDays posology object 
						"TD": { 
							"T": 1, // Dosage only timed dosage 
							"D": { 
								"T": 1, // Simple dosage 
								"A": 1.0 // Take 1 (pill) 
							} 
						}, 
						"E": true // Take on even days 
					} 
				} 
			], 
			"U": "TABL" // Quantity unit
		} 
	] 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-posology-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-posology-object-type",
            "code" : "6",
            "display" : "Even/odd days"
          }
        },
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "1",
            "display" : "DosageOnly"
          }
        }
      ],
      "additionalInstruction" : [
        {
          "coding" : [
            {
              "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-even-odd-days",
              "code" : "even",
              "display" : "Even days"
            }
          ]
        }
      ],
      "timing" : {
        "repeat" : {
          "boundsPeriod" : {
            "start" : "2021-01-02"
          },
          "frequency" : 1,
          "period" : 2,
          "periodUnit" : "d"
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Tablet (unit of presentation)",
            "system" : "http://snomed.info/sct",
            "code" : "732936001"
          }
        }
      ]
    }
  ]

Timed Dosage Objects

Different types of timed dosage objects are defined in CHMED23A to specify the moment and amount of an application of a medicament. Details and examples for the 6 types (DosageOnly, Times, DaySegments, WeekDays, DaysOfMonth, Interval) are described in the following sections.

DosageOnly

Specifies a dosage without specifying a precise taking moment.

Example: Take 1.

CHMED23A format for DosageOnly:

{ 
	"T": 1, // DosageOnly timed dosage object 
	"D": { 
		"T": 1, // Simple dosage dosage object 
		"A": 1.0 // Amount of 1 
	} 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "1",
            "display" : "DosageOnly"
          }
        }
      ],
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Times

Specifies precise times when a medicament must be applied.

CAVE:
The FHIR mapping of ‘Times’ is in the Dosage.timing.repeat.timeOfDay element from data type time. This allows to specify a time of day in the format hh:mm:ss.

Example: Take 1 at 08:00.

CHMED23A format for Times:

{ 
	"T": 2, // Times timed dosage object 
	"Ts": [ 
		{ 
			"OffU": 3, // Offset unit is hours 
			"Off": 8, // Offset of 8 (hours) 
			"D": { 
				"T": 1, // Simple dosage dosage object 
				"A": 1.0 // Amount of 1 
			} 
		} 
	] 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "2",
            "display" : "Times"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "timeOfDay" : [
            "08:00:00"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

DaySegments

Specifies the day segment (morning, noon, evening, night) when a medicament must be applied.

Example: Take 1 in the evening.

CHMED23A format for DaySegments:

{ 
	"T": 3, // DaySegments timed dosage object 
	"Ts": [ 
		{ 
			"S": 3, // Evening segment 
			"D": { 
				"T": 1, // Simple dosage dosage object 
				"A": 1.0 // Amount of 1 
			} 
		} 
	] 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "3",
            "display" : "DaySegments"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "when" : [
            "EVE"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

WeekDays

Specifies on which days of the week a medicament must be applied.

Days of week
  1. Monday -> mon
  2. Tuesday -> tue
  3. Wednesday -> wed
  4. Thursday -> thu
  5. Friday -> fri
  6. Saturday -> sat
  7. Sunday -> sun

Example: Take 1 on Monday, Wednesday and Friday.

CHMED23A format for WeekDays:

{ 
	"T": 4, // Weekdays timed dosage object 
	"WDs": [ 1, 3, 5 ], // Days of week Monday, Wednesday, Friday 
	"TD": { 
		"T": 1, // Dosage only timed dosage 
		"D": { 
			"T": 1, // Simple dosage dosage type 
			"A": 1.0 // Amount of 1 
		} 
	} 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "4",
            "display" : "WeekDays"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "dayOfWeek" : [
            "mon",
            "wed",
            "fri"
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

DaysOfMonth

Specifies on which days of the month a medicament must be applied.

Example: Take 1 on the 1st and 15th of the month.

CHMED23A format for DaysOfMonth:

{ 
	"T": 5, // DaysOfMonth timed dosage 
	"Ds": [ 1, 15 ], // Specified days in month 
	"TD": { 
		"T": 1, // DosageOnly timed dosage 
		"D": { 
			"T": 1, // Simple dosage dosage object 
			"A": 1.0 // Amount of 1 
		} 
	} 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "5",
            "display" : "DaysOfMonth"
          }
        }
      ],
      "timing" : {
        "repeat" : {
          "extension" : [
            {
              "url" : "http://hl7.org/fhir/StructureDefinition/timing-dayOfMonth",
              "valuePositiveInt" : 1
            },
            {
              "url" : "http://hl7.org/fhir/StructureDefinition/timing-dayOfMonth",
              "valuePositiveInt" : 15
            }
          ]
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

Interval

Specifies the application of a medicament with a minimal interval between two applications.

Example: Apply medication with a minimal interval of 6 hours between two applications.

CHMED23A format for Interval:

{ 
	"T": 6, // Interval timed dosage 
	"D": { … }, 
	"MIDU": 3, // Min interval duration unit in hours 
	"MID": 6 // Min interval of 6 (hours)
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "extension" : [
        {
          "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-timed-dosage-object-type",
          "valueCoding" : {
            "system" : "http://chmed.emediplan.ch/fhir/CodeSystem/chmed-codesystem-timed-dosage-object-type",
            "code" : "6",
            "display" : "Interval"
          }
        }
      ],
      "maxDosePerPeriod" : {
        "numerator" : {
          "value" : 1.0,
          "unit" : "Piece",
          "system" : "http://unitsofmeasure.org",
          "code" : "{Piece}"
        },
        "denominator" : {
          "value" : 6,
          "unit" : "Hour",
          "system" : "http://unitsofmeasure.org",
          "code" : "h"
        }
      }
    }
  ]

Dosage Objects

Dosage objects are specified in CHMED23A and describe the amount of a medication that must be applied. Details and examples for the 3 types (DosageSimple, DosageFromTo, DosageRange) are described in the following sections.

DosageSimple

Specifies a simple amount. E.g., 1 (pill) or 10 (ml).

Example: Take 1.

CHMED23A format for DosageSimple:

{ 
	"T": 1, // Simple dosage 
	"A": 1.0 // Amount of 1 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "value" : 1.0,
            "unit" : "Piece",
            "system" : "http://unitsofmeasure.org",
            "code" : "{Piece}"
          }
        }
      ]
    }
  ]

DosageFromTo

Specifies how a dosage changes during time. This can be e.g., used for infusions.

If the dosage changes, multiple dosage elements have to be defined in FHIR; see example increasing dosage every hour or tapered dosing.
An extension has been defined to change the quantity from the starting quantity continously to the final quantity (see example below):

Example: Start with a dosage of 5, end with a dosage of 10 during a time interval of 45 minutes.

CHMED23A format for DosageFromTo:

{ 
	"T": 2, // DosageFromTo 
	"AFrom": 5.0, // Start amount is 5 
	"ATo": 10.0, // End amount is 10 
	"DuU": 2, // Duration unit is minutes 
	"Du": 45 // Duration is 45 (minutes) 
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "timing" : {
        "repeat" : {
          "duration" : 45,
          "durationUnit" : "min"
        }
      },
      "doseAndRate" : [
        {
          "doseQuantity" : {
            "extension" : [
              {
                "url" : "http://chmed.emediplan.ch/fhir/StructureDefinition/chmed-dose-quantity-to",
                "valueQuantity" : {
                  "value" : 10.0,
                  "unit" : "milliliter",
                  "system" : "http://unitsofmeasure.org",
                  "code" : "mL"
                }
              }
            ],
            "value" : 5.0,
            "unit" : "milliliter",
            "system" : "http://unitsofmeasure.org",
            "code" : "mL"
          }
        }
      ]
    }
  ]

DosageRange

With a dosage range a min and must amount must be specified.

Example: Take 1 in the evening.

CHMED23A format for DosageRange:

{ 
	"T": 3, // DosageRange dosage 
	"AMin": 1.0, // Minimum amount of 1 
	"AMax": 3.0 // Maximum amount of 3
}

FHIR format for Dosage (see also example):

  "dosage" : [
    {
      "doseAndRate" : [
        {
          "doseRange" : {
            "low" : {
              "value" : 1.0,
              "unit" : "Piece",
              "system" : "http://unitsofmeasure.org",
              "code" : "{Piece}"
            },
            "high" : {
              "value" : 3.0,
              "unit" : "Piece",
              "system" : "http://unitsofmeasure.org",
              "code" : "{Piece}"
            }
          }
        }
      ]
    }
  ]

Sequence Objects

Sequence objects are defined in CHMED23A to specify a sequence of posologies that have to be respected in the correct order and can possibly be repeated. Details and examples for the 2 types (PosologySequence, Pause) are described in the following sections.

PosologySequence

Wraps any type of posology object in order to create a sequence.

Example: Take 1 daily for 21 days.

CHMED23A format for PosologySequence:

{ 
  "T": 1, // Posology sequence sequence object 
  "PO": { 
    "T": 4, // Cyclic posology object 
    "CyDuU": 4, // Day unit 
    "CyDu": 1, // Cycle lasts 1 (day) 
    "TD": { 
      "T": 1, // Dosage only timed dosage 
      "D": { 
        "T": 1, // Simple dosage 
        "A": 1.0 // Amount of 1 
      } 
    } 
  }, 
  "DuU": 4, // Day unit 
  "Du": 21 // Sequence lasts 21 (days) 
}

FHIR format for Dosage; see sequence 0 in this example.

Pause

Specifies a duration of a break sequence where the medication doesn’t have to be applied.

Example: Break of 7 days.

CHMED23A format for Pause:

{ 
  "T": 2, // Pause sequence object 
  "DuU": 4, // Day unit 
  "Du": 7 // Pause lasts 7 (days) 
}

FHIR format for Dosage; see sequence 1 in this example.

Taking Objects

Taking objects are defined in CHMED23A to specify a dosage that must be applied at certain times; either at a precise time or in a day’s segment (morning, noon, evening or night). Details and examples for the 2 possibilities (TakingAtTime, TakingInSegment) are described in the following sections.

TakingAtTime

Specifies a precise moment in time when a medicament must be applied.

Example: Take 1 at 08:00.

CHMED23A format for TakingAtTime:

{ 
  "OffU": 3, // Offset in hours 
  "Off": 8, // Offset of 8 (hours) 
  "D": { 
    "T": 1, // Simple dosage dosage type 
    "A": 1.0 // Amount of 1 
  } 
}

FHIR format for Dosage; see timing in this example.

TakingInSegment

Specifies a day segment (morning, noon, evening or night) when a medicament must be applied.

Example: Take 1 in the evening.

CHMED23A format for TakingInSegment:

{ 
  "S": 3, // Evening day segment 
  "D": { 
    "T": 1, // Simple dosage dosage type 
    "A": 1.0 // Amount of 1 
  } 
}

FHIR format for Dosage; see timing in this example.