Post on 12-Jan-2016
description
The Use of the World Health Organization’sDefined Daily Dose in Drug Cost & Utilization Analyses
Elena LunguSenior Economist
2008 CADTH Symposium Edmonton, AlbertaApril 29th, 2008
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Established in September 2001 by F/P/T Ministers of Health
Responsibilities of PMPRB established by the Minister of Health, pursuant to Section 90 of the Patent Act
Purpose: to facilitate informed administration of public drug plans in
Canada by providing:
Timely, standardized and comparative prescription drug information from participating public drug plans in response the priorities identified by the F/P/T Steering Committee
Critical analyses of price, utilization and cost trends Collaborative initiative between CIHI and the PMPRB
National Prescription Drug Utilization Information SystemNPDUIS
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Purpose of the Study
Reliable quantity measures are the foundation of drug utilization studies
There is a need to transform the physical units into treatment units
The Defined Daily Dose (DDD) widely utilized by researchers
As it converts the physical quantities into a standards unit of measure: ‘day’
NPDUIS has applied the DDD methodology to drug utilization studies &
gained a strong understanding of the advantages & limitations to applying
DDD in the context of Canadian administrative databases, & identified:
Concerns regarding results interpretation that limit the applicability of DDD
methodology
The need to consider other quantity measures (e.g. the reported Day Supply)
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DDD Definition
Units Total DDDs58M 58M45M 90M18M 73M
2M 18M123M 240M
Assumed average maintenance dose per day
for a drug used for its main indication in adults
Initial dose not captured (if different than maintenance)
Average of two or more commonly used dose sizes
Average of two or more commonly used dose sizes
+ 95%
Based on a review of the available information including doses used in various countries when this information is available
Other indications not captured
Children dose not captured, except in drugs prescribed only to children
Ingredient & form
Example:
Atorvastatin
DDD = 10mg
Strength DDDs10mg 120mg 240mg 480mg 8ODB, 2005/06
TOTAL
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DDD in Canadian Administrative Databases
Advantages Limitations
Maintained & updated by WHO Integration in Canadian Administrative Databases
Interpretation of Canadian UtilizationReadily available, inexpensive &
easy to use
Allows integrationwith other databases
Valuable comparative measureof drug exposure
Applicability in Cost Analyses
Applicability in Policy Decisions
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DDD – Integration in Canadian Admin. Databases
Overwhelming majority of drug utilization is for drugs with ATC assigned Significant utilization for drugs without DDD:
10% of Cost, 12 % of Rx in NPDUIS Selected Public Plans: NS, NB, MB & SK
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DDD methodology relies on reported units: Canadian data may be reported in unit measure different than the ATC/DDD
system – Unit conversion required Even for the same DIN, the reported unit of measure may differ – Unit
standardization required Inaccurate unit reporting may occur
linkAdmR ATC/DDD system
Form Canadian Admin. Databases
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DDD – Interpretation of Canadian Utilization
Apply ATC/DDD methodology & interpret with caution
Technical Drug Use Metric – “rarely if ever prescribed” WHO
May not be reflective of the avg. daily dose in Canada, due to differences in:
May not mirror the drug utilization of selected segments of population (demographic or therapeutic skewing)
Purely a comparative measure of drug exposure DDD not appropriate in making assumptions on treatment lengths
• Demographics• Approved indications• Disease prevalence
• Reimbursement policies• Prescribing practices• Etc.
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DDD – Interpretation of Canadian Utilization
99%
Units Distribution
55%
34%
11%
2%
15%
36%
47%
0%
10%
20%
30%
40%
50%
60%
10mg 20mg 40mg 80mg
2001/02 2005/06
Example: Atorvastatin in ODB – DDD 10mg
2001/02
Strength DDDs Units Total DDDs
10mg 1 34M 34M
20mg 2 21M 42M
40mg 4 7M 28M
80mg 8 - -
TOTAL 62M 104M
2005/06
Strength DDDs Units Total DDDs
10mg 1 58M 58M
20mg 2 45M 90M
40mg 4 18M 73M
80mg 8 2M 18M
TOTAL 123M 240M
Higher Drug Exposure 130%
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DDD – Applicability in Cost Analyses
“It is usually not valid to use this metric to compare costs of different drugs or drug groups”
WHO
DDD Misuses in Cost Analyses: Simple average cost at DDD level across drugs
Comparison of actual or % difference in avg. cost at DDD level not appropriate Cost decomposition
Contribution of individual effects distorted Cost per illness, cost-benefit, cost-effectiveness & cost utility analyses Budget Impact Analyses
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DDD – Applicability in Cost Analyses (Cont’d)
2001/02
Strength DDDs Units Total DDD Avg. Cost/Unit Avg. Cost/DDD
10mg 1 34M 34M $1.60 $1.60
20mg 2 21M 42M $2.00 $1.00
40mg 4 7M 28M $2.15 $0.54
80mg 8 - - - -
TOTAL 62M 104M $1.80 $1.07
2005/06
Strength DDDs Units Total DDD Avg. Cost/Unit Avg. Cost/DDD
10mg 1 58M 58M $1.62 $1.62
20mg 2 45M 90M $2.03 $1.02
40mg 4 18M 73M $2.18 $0.55
80mg 8 2M 18M $2.18 $0.27
TOTAL 123M 240M $1.87 $0.96
4% -10%
Example: Atorvastatin in ODB – DDD 10mg
99% 130%
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DDD – Applicability in Cost Analyses (Cont’d)
DDD in Cost Drivers Analysis
Main ingredients: Price & Quantity
If quantity expressed in DDDs, then:
Price Effect: accurate if calculated at DIN level
As it represents the price differential as opposed to actual price Volume Effect: may be overstated or understated
As it represents the drug exposure as opposed to actual treatment units Therapeutic-Mix: may be inaccurate
As it is based on average cost / DDDExample
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Therapeutic-Mix: Serum Lipid Reducing Agents
Rosuvastatin DDD = 10mg
Strength DDDs Units Total DDDs Avg. Cost/Unit Avg. Cost/DDD
10mg 1 18M 18M $1.36 $1.36
20mg 2 4M 8M $1.70 $0.85
40mg 4 1M 3M $1.99 $0.50
- - - - - -
TOTAL 23M 29M $1.44 $1.14
AtorvastatinDDD = 10mg
Strength DDDs Units Total DDDs Avg. Cost/Unit Avg. Cost/DDD
10mg 1 58M 58M $1.62 $1.62
20mg 2 45M 90M $2.03 $1.02
40mg 4 18M 73M $2.18 $0.55
80mg 8 2M 18M $2.18 $0.27
TOTAL 123M 240M $1.87 $0.96
19% -23%
Example: ODB – 2005/06
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DDD – Applicability in Policy Decision
Misuses of ATC/DDD in Policy Decisions:
Cost analyses based on DDD methodology in support of policy decisions
Determining therapeutic equivalence
Reimbursement decisions
Therapeutic group reference pricing decisions & other pricing decisions
Price comparisons
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Conclusions – DDD Methodology
A valuable comparative measure of drug exposure
Regional (interprovincial, international, etc.) & trend analyses Best applied to specific classes of drugs
Comprehensive studies may not be all that comprehensive DDD may align better with actual daily dose in some classes/drugs than other Integration process may be eased
Best applied at population level, as opposed to specific population segments DDD – generally not appropriate in a broad array of Cost Analyses on
multiple drugs Caution required when applying the DDD methodology in analyses in
support of policy decisions
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Unavailable in some administrative databases
Day Supply Information Fieldin Canadian Administrative Databases
Already integrated in some drug plan administrative databases
Possible misreporting
Difficult to interpret in non-daily treatmentsClaim specific
Actual drug utilization
Advantages Limitations
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Scope:
2005/06 fiscal year, NPDUIS selected drug plans: PEI, NS, NB, ON & NIHB
Methods: Avg. Daily Supply (Units/Days) & Avg. Rx Length (Days/Rx)
Results – for the above scope: Avg. Daily Supply at drug & strength level comparable across plans Avg. Rx Length at plan level comparable across drugs
Day Supply information field quality assurance is a prerequisite
Day Supply Information FieldPreliminary Quality Investigation
• Agents Acting on Renin-Angiotensin System• Serum Lipid Reducing Agents • Drugs for Acid-Related Disorders• Psychoanaleptics
Similar utilization patterns
Oral solids
Conclusion: When available & for specific classes of drugs, Day Supply is a valuable information field & may be used in drug utilization & cost analyses
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Understand the research question & its scope
Know the data availability & quality
Know the advantages & limitations of the available quantity measures
given the context
Decide on the most appropriate quantity measure to report on
Recognize that these quantity measures may capture partial drug
utilization (unavailable DDD, unreliable Day Supply, etc.)
Take away:– It depends…What’s the best quantity measure?
If the actual daily dose were to differ than the DDD,would the findings change?