217:
methodology "should generally not be used to interpret
Canadian drug utilization; should generally not be applied in cost analyses; and should generally not be applied in policy decisions". The Board recommend that provided the agreement between DDD and RDD is known and minimal, then a cost per DDD "can provide a rough idea of the treatment cost" but "caution should still be used, as misinterpretation of the results based on the DDD methodology may still occur". If the agreement between DDD and RDD is unknown or a significant disagreement is known, then the DDD methodology "should not be used in cost analyses". In all cases, the Board state "The DDD methodology should not be used in guiding policy decisions regarding reimbursement, therapeutic substitution and other pricing decisions".
197:($ 1.14 compared to $ 0.94), which would suggest the shift at the time from prescribing atorvastatin to prescribing rosuvastatin would result in increased costs to the healthcare budget. Both had a DDD at that time of 10mg, but 10mg was not the only dose prescribed. For example, atorvastatin once daily at 10mg, 20mg, 40mg and 80mg was prescribed 45%, 36%, 16% and 3% of the time respectively. If one compared
79:
formulations of a drug, however exceptions are made if some formulations are typically used in significantly different strengths (e.g., antibiotic injection in a hospital vs tablets in the community). The DDD of combination tablets (containing more than one drug) is more complex, most taking into account a "unit dose", though combination tablets used for
118:
sometimes a "dose" not actually ever prescribed (e.g., a midpoint of two prescribed tablet strengths may not be equal to or be a multiple of any available tablet). Different people may in practice be prescribed higher or lower doses than the DDD, for instance in children, people with liver or kidney impairment, patients with a
137:
Although designed primarily for drug utilisation research, data using the DDD can only give a "rough estimate" compared with actually collecting statistics on drug use in practice. The DDD is often use for long term research and analysis of drug utilisation trends over time, so changes to the DDD are
78:
and be approved for sale in at least one country. The DDD is calculated for a 70kg adult, except if this drug is only ever used in children. The dose is based on recommendations for treatment rather than prevention, except if prevention is the main indication. Generally there is only one DDD for all
181:
In contrast, using DDD to compare the cost of different drugs or drug groups is "usually not valid" according to the WHO. They recommend that "DDDs are not suitable for comparing drugs for specific, detailed pricing, reimbursement and cost-containment decisions". The DDD may not necessarily compare
216:
analysed the use of DDD for drug utilisation and cost analysis and offered recommendations. They particularly concentrated on the problems that occur when the
Recorded Daily Dose (RDD) observed in the population deviates more than minimally from the Defined Daily Dose. They conclude that the DDD
442:
has a DDD of 3 g, which means that an average patient who takes paracetamol for its main indication, which is pain relief, uses 3 grams per day. This is equivalent to six standard tablets of 500 mg each. If a patient consumes 24 such tablets (12 g of paracetamol in total) over a
169:
can be used for drugs normally prescribed for short treatment duration (e.g., antibiotics) to indicate the average number of days in a year a person may take that treatment. The extent to which estimates using DDD reflect actual clinical practice depends on how close the DDD is to the typical
117:
The DDD is generally the same for all formulations of a drug, even if some (e.g., flavoured syrup) are designed with children in mind. Some types of drug are not assigned a DDD, for example: medicines applied to the skin, anaesthetics and vaccines. Because the DDD is a calculated value, it is
50:
drug classification system for grouping related drugs. The DDD enables comparison of drug usage between different drugs in the same group or between different health care environments, or to look at trends in drug utilisation over time. The DDD is not to be confused with the
173:
Because the primary purpose of the ATC/DDD system is drug consumption measurement, the WHO recommend caution when considering its use for cost analysis: "DDDs, if used with caution can be used to compare, for example, the costs of two formulations of the same drug." So, the
430:
108:
The DDD of a drug is reviewed after three years. Ad hoc requests for change may be made but are discouraged and generally not permitted unless the main indication for the drug has changed or the average dose used has changed by more than 50%.
614:
209:. At the time, the RDD of rosuvastatin was similar to its DDD (12.6 mg vs 10mg), but the RDD of atorvastatin was twice its DDD (20.6 mg vs 10mg). The DDD of atorvastatin was revised in 2009 to 20mg.
205:(recorded daily dose) then rosuvastatin was 26% cheaper than atorvastatin ($ 1.43 vs $ 1.93). An erroneous conclusion of a healthcare budget cost increase arises in this case from using
178:
of an extended-release tablet taken once a day compared with a standard tablet taken twice a day, may indicate the extended-release tablet costs much more to treat the same condition.
624:
75:
47:
230:
448:
138:
avoided if possible, whereas changes in the actual daily dose prescribed for a population may often occur. For example, the
Recorded Daily Dose (RDD) of
225:
If the DDD for a certain drug is given, the number of DDDs used by an individual patient or (more commonly) by a collective of patients is as follows.
213:
182:
well with the actual prescribed daily dose, and two drugs in the same ATC group may not be equally effective at their Daily
Defined Dose.
59:(PDD), or recorded daily dose (RDD), and will often be different to the dose actually prescribed by a physician for an individual person.
149:
The DDD is based on the maintenance dose, but in practice patients in a population will be on a mix of initial and maintenance doses.
685:
96:
If the literature recommends generally increasing from initial to maximum dose provided it is tolerated, pick the maximum dose.
66:
per day for a drug used for its main indication in adults." The
Defined Daily Dose was first developed in the late 1970s.
99:
If the literature recommends only increasing from an initial dose if not sufficiently effective, pick the minimum dose.
201:(daily tablet) then rosuvastatin was instead 24% cheaper than atorvastatin ($ 1.44 vs $ 1.90), and if one compares
142:
in Canada in 1997 was only 8% different to the DDD, but by 2006 it was 67% different. In 2009, the DDD of several
43:
630:
74:
Before a DDD is assigned by the WHO Collaborating Centre for Drug
Statistics Methodology, it must have an
742:"Use of the World Health Organization Defined Daily Dose in Canadian Drug Utilization and Cost Analyses"
639:
56:
157:
The DDD can be used as the basis for calculating various indicators of drug utilisation. The indicator
425:{\displaystyle Drug\ usage\ (in\ DDDs)={\frac {Items\ issued\times Amount\ of\ drug\ per\ item}{DDD}}}
161:
can suggest what portion of a population are regularly using a drug or class of drugs. The indicator
131:
119:
46:(WHO) Collaborating Centre for Drug Statistics Methodology. It is defined in combination with the
39:
185:
For example, an analysis of statin use in the
Ontario Drug Benefit Program, 2006-07. The average
686:"Introduction to Drug Utilization Research: Preface: Drug utilization research - the early work"
165:
estimates on average how many inpatients are given a drug every day in hospital. The indicator
802:
609:{\displaystyle Drug\ usage\ (in\ DDDs)={\frac {24\ (items)\times 500\ (mg/item)}{3000\ mg}}=4}
718:
673:
63:
52:
123:
693:
90:
If there is a single recommended maintenance dose in the literature, this is preferred.
796:
194:
190:
80:
17:
741:
439:
139:
127:
102:
If there is no guidance then pick the mid point between the dose range extremes.
435:
170:
prescribed dose in that country or setting and at that point in history.
772:
634:
143:
771:
WHO Collaborating Centre for Drug
Statistics Methodology (WHOCC):
717:
WHO Collaborating Centre for Drug
Statistics Methodology (WHOCC):
672:
WHO Collaborating Centre for Drug
Statistics Methodology (WHOCC):
443:
certain span of time, this equals a consumption of four DDDs.
642: – Usual dose of a medication for a specific condition
146:
were updated, with simvastatin changing from 15mg to 30mg.
93:
If there are a range of recommended maintenance doses then
62:
The WHO's definition is: "The DDD is the assumed average
787:
625:
Anatomical Therapeutic Chemical Classification System
451:
233:
608:
424:
83:take the number of doses per day into account.
788:World Health Organisation Collaborating Centre
8:
767:
765:
763:
713:
711:
674:DDD Definition and general considerations
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86:The formula for determining the dose is:
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27:Statistical measure of drug consumption
214:Patented Medicine Prices Review Board
7:
627: – Drug classification system
25:
159:DDD per 1000 inhabitants per day
719:Application for DDD alterations
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554:
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509:
485:
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267:
38:) is a statistical measure of
1:
193:was 21% more expensive than
167:DDDs per inhabitant per year
42:consumption, defined by the
122:, or due to differences in
819:
633:(ADQ), an alternative in
44:World Health Organization
126:between individuals or
631:Average daily quantity
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426:
640:Prescribed daily dose
611:
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57:prescribed daily dose
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231:
163:DDD per 100 bed days
132:genetic polymorphism
120:combination therapy
81:high blood pressure
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32:defined daily dose
18:Defined Daily Dose
746:pmprb-cepmb.gc.ca
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434:For example, the
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16:(Redirected from
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775:
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692:. Archived from
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438:(pain reliever)
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64:maintenance dose
53:therapeutic dose
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696:on May 28, 2010
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124:drug metabolism
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28:
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11:
5:
816:
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782:External links
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773:Use of ATC/DDD
759:
748:. 19 June 2014
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153:Use and misuse
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212:The Canadian
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199:cost per unit
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750:. Retrieved
745:
698:. Retrieved
694:the original
690:apps.who.int
689:
680:
445:
433:
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211:
207:cost per DDD
206:
203:cost per RDD
202:
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195:atorvastatin
191:rosuvastatin
187:cost per DDD
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176:cost per DDD
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85:
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29:
440:paracetamol
140:simvastatin
128:ethnicities
113:Limitations
752:10 January
700:10 January
647:References
70:Assignment
546:×
436:analgesic
337:×
803:Pharmacy
797:Category
619:See also
76:ATC Code
48:ATC Code
635:England
221:Example
144:statins
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754:2020
702:2020
586:3000
40:drug
30:The
549:500
189:of
134:).
55:or
36:DDD
799::
762:^
744:.
725:^
710:^
688:.
655:^
519:24
756:.
704:.
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601:=
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581:)
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572:t
569:i
565:/
561:g
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555:(
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525:(
513:=
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486:(
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20:)
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