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Drug utilization research is an essential part of Pharmaco-epidemiology.
Without a knowledge of how drugs are being prescribed and used, it is difficult to initiate a discussion on rational drug use or to suggest measures to improve prescribing habits.
To assess whether interventions undertaken to improve drug use have had desired impact or not
Last point eg - Relative use of drug groups in the treatment of hypertension- ACEI, diuretics, CCBs Relative use of different beta blockers in hypertension
E.g. Hypertension, URTI, gastric ulcer
Age- NSAID causing more gastric damage & Sulphonylureas causing more hypoglycemia in elderly Co-morbidity – b-blocker not in asthmatic for HTN, aminoglycosides not in renal compromised pt for any infection Knowledge- pressure on doctors for prescribing drugs
3rd point eg Digoxin
Do these variations indicate a need to target education to particular sectors ?
Difficult to obtain especially in environments with weak drug regulation and poor record keeping.
Most internet prescriptions are for nutritional supplements and herbal preparations.
Dispensing data and utilization data may not be equivalent.
E.g. Amoxicillin – 500mg TDS usual dose, but DDD is 1 gm.
Azithromycin for uncomplicated urti -500mg od*3days, for gonococcal urethritis 1gm stat, for typhoid-500mg bd*1day-500mg od*4days Metronidazole for Invasive Amoebiasis and for Moniliasis PDDs are often lower in Asian than in Caucasian populations.
Increase in du90 reflects better quality drug use & policy adherence
E.g. blood glucose levels in males and females, drug use in males and females
DUS_Dr. Mansij Biswas
Drug Utilization Studies
Dr. Mansij Biswas, SYR
Department of Pharmacology & Therapeutics
Seth G S Medical College & KEM Hospital
Introduction & Definition:
Pharmaco-epidemiology is the study of use and effects
or side-effects of drugs in large number of people with
the purpose of supporting the rational and cost effective
use of drugs in population, thereby improving health
WHO defines drug utilization research as, “the
marketing, distribution, prescription and the use of
drugs in a society with special emphasis on the resulting
medical, social and economic consequences.”(WHO,
June 7th, 2014
INTRODUCTION TO DRUG UTILIZATION RESEARCH, WHO International Working Group For
Drug Statistics Methodology, WHO Collaborating Centre For Drug Statistics Methodology, WHO, 2003.
Initiated in Northern Europe and The UK in the mid
Arthur Engel in Sweden and Pieter Siderius in Holland
described importance of comparing drug use between
different countries and regions
Differences in sales of antibiotics in six European
countries between 1966 and 1967 inspired WHO to
organize first meeting on drug consumption in Oslo,
June 7th, 2014 3
Constitution of WHO European Drug Utilization
Research Group (DURG)
Development of a new unit of measurement, initially
called the agreed daily dose and later the Defined Daily
Dose (DDD), by researchers from Ireland, Norway &
The first study used anti-diabetic drugs as an example
Among the first countries to adopt the DDD
methodology was the former Czechoslovakia
First comprehensive national list of DDD was published
in Norway in 1975
June 7th, 2014 4
Why drug utilization research?
The principal aim is to facilitate the rational use of
drugs in populations.
Rational use of medicines (RUM) is defined as
“Patients receive medications appropriate to their
clinical needs, in doses that meet their own individual
requirements, for an adequate period of time, and at the
lowest cost to them and their community” (WHO, 1985)
June 7th, 2014
Promoting Rational Use of Medicines: Core Components - WHO Policy Perspectives on
Medicines, No. 005, September 2002 5
Description of drug use pattern
Early signals of irrational use of drugs
Interventions to improve drug use – follow up &
assessing the impact
Quality control of drug use
June 7th, 2014 6
Description of drug use pattern : -
Drug utilization research will increase our understanding of
how drugs are being used by-
Estimating the numbers of patients exposed to specified
drugs within a given time period.
Getting extent of use at certain moment or area.
Estimating to what extent drugs are properly used,
overused or underused.
June 7th, 2014 7
Determining pattern or profile of drug use and the
extent to which alternative drugs are being used to
treat particular conditions.
Comparing the observed patterns of drug use for the
treatment of certain disease with current guidelines.
Giving feedback of the drug utilization data to
Assessing the potential magnitude of the problem
June 7th, 2014 8
Early signals of irrational use of drugs:
Comparing drug utilization patterns and cost
between different regions or time period
Comparing observed patterns of drug use with
current recommendation or guidelines for the
treatment of certain disease
June 7th, 2014 9
Interventions to improve drug use-follow
Monitoring and evaluating the effects of measures
taken to improve undesirable patterns of drug use
Following the impact of regulatory changes or
changes in the insurance or reimbursement schemes
To which extent promotional activities of the
pharmaceutical industry and educational activities of
the society impact on the patterns of drug use
June 7th, 2014 10
Quality control of drug use:
Drug use should be controlled according to a quality control
cycle that offers a systematic framework for continuous
Step 1 : PLAN –
Analyze the current
situation to establish
plan for improvement
Step 2 : DO –
Implement the plan on
Step 4 : ACT – Revise
plan or implement plan
Step 3 : CHECK –
Check to see if
expected results are
June 7th, 2014 11
on large scale
Types of drug use information
Drug based information
Problem or encounter based information
Patient based information
Prescriber based information
Cost based information
June 7th, 2014 12
A) Drug based informations
◦ Data on drug use on various levels, and
information on indications, doses and dosage
regimen is usually necessary
◦ Level of drug use aggregation : The level at
which data on drug use are aggregated will
depend on question being asked.
June 7th, 2014 13
◦ For drugs with multiple indications, it will
usually be important to divide data on use
according to indication to allow a correct
interpretation of the overall trends.
◦ antibiotic utilization
◦ Use of beta-blockers
June 7th, 2014 14
B) Problem based informations
◦ Useful to address the question – how a particular
problem is managed.
Questions that might be addressed:
◦ Does the severity of the disease influence the
choice of single or combination therapy ?
◦ Is the management of newly-presenting patients
different to that of patients already receiving
◦ Are there likely to be any drug interactions with
co-prescribed treatments ?
◦ Is the choice of drug influenced by evidence
based outcome data ?
June 7th, 2014 15
C) Patient based informations
Information on demographic factors and other
details about the patient are useful
Age distribution – to assess the likelihood of severe
adverse effects with some drugs
Comorbidities of patient
Knowledge, beliefs and perceptions of patients and
their attitudes to drugs are important
June 7th, 2014 16
D) Prescriber based informations
This information is useful to understand how
and why drugs are prescribed.
◦ Some questions that might be addressed:
Are prescribing profiles influenced by the
prescriber’s medical education?
Do the prescribing profiles of specialists differ from
those of general practitioners ?
Does the age or gender of the prescriber influence
the prescribing profile?
June 7th, 2014 17
Are there differences in prescribing behavior
between urban and rural practices or between
small and large practices ?
Who are those prescribers who rapidly adopt to
recently released drugs ?
Can the factors that determine and change
prescribing behavior be identified ?
June 7th, 2014 18
E) Cost based informations
It will always be important in managing policy
related to drug supply, pricing and use.
E.g. Use of antipsychotic drugs in Australia
June 7th, 2014 19
The DUS cycle:
June 7th, 2014 20
Steps involved in
conducting a drug
June 7th, 2014 21
Step 1:- Identify drugs or therapeutic
areas of practice for inclusion in the
a) The systems and structures surrounding drug use
e.g. how drugs are ordered, delivered and administered in
a hospital or health care facility
b) The processes of drug use
e.g. what drugs are used and how they are used and does
their use comply with the relevant criteria, guidelines or
June 7th, 2014 22
c) The outcome of drug use
e.g. efficacy, adverse drug reactions and the use of
resources such as drugs, laboratory tests, hospital
beds or procedures.
Drug utilization studies can be targeted towards any
of the above links in the drug use chain.
June 7th, 2014 23
Generally drugs with a high volume of use, high cost or
high frequency of adverse drug reactions are subjected to
Commonly prescribed drugs e.g. Antibiotics, PPIs, etc.
Drugs with significant drug interactions e.g. Warfarin,
Expensive drugs e.g. LMWH, Cephalosporins
Drugs with a narrow therapeutic index e.g. Digoxin,
Drugs with serious ADRs e.g. aminoglycoside, NSAIDs etc.
Drugs in high risk patients e.g. elderly, pediatric patients
Drugs in the management of common conditions e.g. RTI or
UTI, HTN, T2DM etc
June 7th, 2014 24
Step 2:- Design of study
In designing the DU study, observational research methods
are more commonly used.
Accordingly, DU study can be
June 7th, 2014 25
Used to describe present situation and the trends in the
drug prescription and drug use at various levels of the
health care system.
Assess the appropriateness of drug utilization and link
the prescribing data to reasons for prescribing. It can be
referred as Drug Utilization Review or Drug Utilization
Evaluation. This process is one of the
June 7th, 2014 26
Cross sectional studies-
Provide a snapshot of drug use at a particular time like
over a year, a month or a day
Used for making comparisons with similar data
collected over the same period in a different country,
health facility or a ward
Can be carried out before and after an intervention
Studies can simply measure drug use, or can be utilized
to assess drug use in relation to guidelines
June 7th, 2014 27
Data can be on total drug use or on a statistically valid
samples from pharmacies or medical practices.
Often obtained from repeated cross sectional surveys.
Data collection is continuous but the practitioner surveyed
and therefore patients are continuously changing.
Such data gives information about overall trends but not
about prescribing trends.
Provide information about concordance with treatment
based on the period between prescriptions, duration of
treatment, PDD etc
June 7th, 2014 28
Continuous longitudinal study-
◦ This data can address a range of issues
including reasons for change in therapy,
adverse effects and health outcomes
June 7th, 2014 29
Step 3:- Define criteria and
With an exhaustive literature search, identify the
key literature in the chosen area of interest and
the drug criteria that can be derived from this
evidence based literature.
Must be valid, unambiguous, realistic, easily
measured and outcome oriented.
June 7th, 2014 30
Step 4:- Design the data collection form
It is impossible to address all aspects of use for each
◦ Patient demographics
◦ Prescriber details
◦ Side/adverse effects
◦ Dosing information
◦ Drug or drug class duplication
◦ Drug interactions
◦ Monitoring of drug therapy
◦ Patient education/instructions
◦ Cost of therapy
individual drug BUT
It is important to limit data collection to only the most
important and relevant aspects of drug use
Aspects of drug use commonly surveyed are -
June 7th, 2014 37337
Step 5:- Data collection
Physicians, pharmacists and nurses make
ideal data collectors.
Different types of drug use information
are required depending upon the problem
June 7th, 2014 32
Source of data
◦ Large databases
◦ Data from drug regulatory agency
◦ Supplier (distribution) data
◦ Practice setting data
◦ Community setting data
June 7th, 2014 33
◦ Efficient use of health care resources - Computer
databases or medical record sections
◦ May be international, national or local- comparative
studies can be planned at various levels.
◦ May be diagnosis linked or non-diagnosis linked
◦ Diagnosis linked data enable drug use to be
analyzed according to patients characteristics,
therapeutic groups, diseases or conditions and,
June 7th, 2014 34
Data from drug regulatory agencies:-
Are repositories of data on which drugs have been
registered for use, withdrawn or banned within a
Agencies have the legal responsibility of ensuring the
availability of safe, efficacious and good quality drugs
Possible to obtain data on the number of drugs
registered in a country from such agencies.
Importation data like product type (i.e. generic or
branded), volume, port of origin, country of
manufacture, batch number and expiry date may be
June 7th, 2014 35
Supplier (distribution) data:-
Drug importation; local manufacture; customs
service, whole salers
In countries where licenses are required from drug
regulatory authorities before importation of drugs
Generally be used to describe total quantities of
specific drug or drug group, origins of supplies
and type (i.e. branded or generic)
Distribution at different levels of supplies can be
June 7th, 2014 36
Practice setting data:-
Generate indicators that provide information on
prescribing habits and aspects of patient care.
Aggregate (facility) data
Over-the-counter and pharmacist-prescribed drugs
Telephone and internet prescribing
June 7th, 2014 37
◦ Usually extracted from outpatient and inpatient
◦ Information that may be obtained from
Drug name, dosage form, strength, dose, frequency of
administration and duration of treatment.
Where diagnoses are noted on prescriptions, is
possible to link drug use to indications.
Trends in utilization for specific drugs and diseases
can also be established.
June 7th, 2014 38
Drug dispensing is a process that ends with a client
leaving a drug outlet with a defined quantity of medication
and instructions for using it.
◦ Information available from dispensers may include
Drug (s) prescribed
Average number of items per prescription
Percentage of items prescribed that were actually supplied
(an indicator of availability)
Percentage of drugs adequately labeled
Quantity of medications dispensed
Cost of each item or prescription.
June 7th, 2014 39
◦ Source include – pharmacy stock and dispensing
records, medication error records, adverse drug reaction
records and patient medical records.
◦ Used to obtain information on
The cost of individual drugs and classes of drug
The most and least expensive drugs
The per capita consumption of specific products.
The prevalence of adverse drug reactions.
The prevalence of medication errors.
The percentage of the budget spent on specific drugs
or classes of drug.
June 7th, 2014 40
Over-the-counter and pharmacist-prescribed
◦ Pharmacists and other drug outlet managers may
prescribe over the counter (OTC) preparations or
pharmacist prepared drugs that do not require
prescription by physician.
◦ When such information is available from stock or
dispensing records, it broadens the understanding of
drug utilization patterns.
June 7th, 2014 41
Telephone and Internet prescribing:
Mostly in developed countries.
Innovative ways need to be devised to collect
information on this type of transaction.
June 7th, 2014 42
Community setting data:-
Drugs available in households have either been
prescribed or dispensed at health facilities,
purchased at pharmacy or are over the counter
The drugs may be for the treatment of current
illness or are left over from previous illness.
Data can be collected by performing household
surveys, counting left over pills etc.
June 7th, 2014 43
Step 6:- Evaluate results
Data evaluation is the most critical step in a DUS
Summarize data into the major categories of results
Check where exactly the data shows deviation from the
guidelines and usage criteria
Check whether true deviation exists
Evaluate reasons for this deviation
May be necessary to redefine the criteria
June 7th, 2014 44
Reasons for deviation may include:
◦ Drug being used for new indication
◦ Outdated procedures
◦ Inadequate resources
◦ Gaps in knowledge or misinformation /
Evaluation is done with the help of:-
Drug Utilization Metrics
Drug Use Indicators
Drug classification systems
June 7th, 2014 45
Drug utilization metrics include:-
Defined daily dose
Prescribed daily dose
Other units for presentation of volume
June 7th, 2014 46
Defined daily dose (DDD):-
The DDD is the assumed average maintenance dose per
day for a drug used for its main indication in adults.
DDD is a unit of measurement and does not necessarily
correspond to the recommended or prescribed daily dose
Doses for individual patients and patient groups will
often differ from the DDD as they must be based on
individual characteristics (e.g. age and weight) and
June 7th, 2014 47
It give a rough estimate of consumption and not an exact
picture of actual use.
DDDs provide a fixed unit of measurement independent
of price, currency, package size and strength enabling
the researcher to assess trends in drug consumption and
to perform comparisons between population groups.
Drug utilization figures should ideally be presented as
numbers of DDDs per 1000 inhabitants per day or,
when drug use by inpatients is considered, as DDDs per
June 7th, 2014 48
DDDs per 1000 inhabitants per day:-
◦ Provide a rough estimate of the proportion of the
study population treated daily with a particular drug or
group of drugs.
10 DDDs per 1000 inhabitants per day indicates that 1%
of the population on average might receive a certain
drug or group of drugs daily.
◦ Most useful for chronically used drugs
June 7th, 2014 49
DDDs per inhabitant per year:-
◦ Estimate of the average number of days for which
each inhabitant is treated annually
◦ 5 DDDs per inhabitant per year indicates that the
utilization is equivalent to the treatment of every
inhabitant with a five-day course during a certain year.
June 7th, 2014 50
DDDs are not established for:-
◦ Topical products
◦ Sera, vaccines
◦ Antineoplastic agents
◦ Allergen extracts
◦ General and Local anesthetics
◦ Contrast media
June 7th, 2014 51
Prescribed daily dose (PDD):-
The prescribed daily dose (PDD) is defined as the
average dose prescribed according to a representative
sample of prescriptions.
Can be determined from studies of prescriptions or
medical or pharmacy records
Gives the average daily amount of a drug that is actually
June 7th, 2014 52
The PDD can vary according to both the illness treated
and the national therapeutic traditions.
The PDDs differ:
◦ Between countries and ethnic groups
◦ Between areas or health care facilities within
the same country
◦ For different indications of the same drug
June 7th, 2014 53
PDD does not necessarily reflect actual drug
Specially designed studies including patient
interviews are required to measure actual drug
intake at the patient level (i.e. the consumed
June 7th, 2014 54
Other units for presentation of volume:
These units can be applied only when the use of a single
drug or of well defined combination product is evaluated.
Grams of active ingredient:-
◦ Drugs with low potency will account for a larger
fraction of the total than drugs with high potency
◦ Combined products may also contain different
amounts of active ingredients from plain products
June 7th, 2014 55
Number of tablets:-
◦ Counting numbers of tablets does not reflect the
variations in strengths of tablets, with the result that
low-strength preparations contribute relatively more
than high-strength preparations to the total numbers
Numbers of prescriptions:-
◦ Do not accurately reflect total use, unless total
quantities of drugs per prescription are also considered.
◦ Valuable in measuring the frequency of prescriptions
June 7th, 2014 56
◦ Cost figures are suitable for an overall analysis of
expenditure on drugs.
◦ International comparisons based on cost parameters
can be misleading and have limited value in the
evaluation of drug use.
◦ Difficulties in evaluation may be due to
Price differences between alternative preparations
Fluctuations in currency
Changes in price
June 7th, 2014 57
Drug Use Indicators:-
◦ Average number of drugs per encounter
◦ Percentage of drugs prescribed by generic name
◦ Percentage of encounters with an antibiotic prescribed
◦ Percentage of encounters with an injection prescribed
◦ Percentage of drugs prescribed from essential drugs
list or formulary
June 7th, 2014 58
Patient care indicators
◦ Average consultation time
◦ Average dispensing time
◦ Percentage of drugs actually dispensed
◦ Percentage of drugs adequately labelled
◦ Patients' knowledge of correct dosage
◦ Availability of copy of essential drugs list or formulary
◦ Availability of key drugs
◦ Availability of clinical guidelines
June 7th, 2014 59
Complementary drug use indicators
o Average medicine cost per encounter
o Percentage prescriptions in accordance with clinical
o Percentage of patients treated without drugs
o ** WHO-INRUD (International Network for the
Rational Use of Drugs) –WHO-1993
June 7th, 2014 60
1. Average number of drugs per encounter
total number of different drug products prescribed
Average = --------------------------------------------------------------
number of encounters surveyed
2. Percentage (%) of drugs prescribed by generic name
number of drugs prescribed by generic name × 100
% = ---------------------------------------------------------------
total number of drugs prescribed
June 7th, 2014 61
3. Percentage of encounters with an antibiotic prescribed
4. Percentage of encounters with an injection prescribed
Number of patient encounters during which an antibiotic or an
injectable are prescribed x 100
% = -----------------------------------------------
Total number of encounters surveyed
June 7th, 2014 62
5. Percentage of drugs prescribed from essential drugs list
The number of products prescribed which are listed on the
essential drugs list or local formulary x 100
% = --------------------------------------------------
The total number of drugs prescribed
June 7th, 2014 63
Patient care indicators:-
1. Average consultation time
Total time for a series of consultation
Number of consultations
2. Average dispensing time
Total time for dispensing drugs to a series of patients
Number of encounters
June 7th, 2014 64
3. Percentage of drugs actually dispensed
number of drugs actually dispensed
at the health facility × 100
total number of drugs prescribed
4. Percentage of drugs adequately labeled
number of drug packages containing at least
patient name, drug name and when × 100
the drug should be taken
total number of drug packages dispensed
June 7th, 2014 65
5. Patients' knowledge of correct dosage
To reliably evaluate the correctness of patients'
responses about when they are to take the drugs, clear
guidelines should be developed about common dosage
number of patients who can adequately report the dosage
schedule for all the drugs x 100
total number of patients interviewed
June 7th, 2014 66
1. Availability of copy of essential drugs list or formulary
2. Availability of clinical guidelines
◦ A national essential drugs list or a local formulary and a
clinical guideline must exist
◦ Scored as ‘Yes’ or ‘No’, per facility
3. Availability of key drugs
number of specified products actually in stock × 100
% = ----------------------------------------------------------------
total number of drugs on the checklist
June 7th, 2014 67
Model list of Key Drugs for testing drug
Diarrhoea oral rehydration salts
Acute respiratory tract infections cotrimoxazole tablets
procaine penicillin injection
paediatric paracetamol tablets
Malaria chloroquine tablets
Anaemia ferrous salt + folic acid tablets
Worm infestations mebendazole tablets
Conjunctivitis tetracycline eye ointment
Skin disinfection iodine, gentian violet or local alternative
Fungal skin infection benzoic acid + salicylic acid ointment
Pain/fever acetylsalicylic acid or paracetamol tablets
Prophylactic drugs retinol (vitamin A)
ferrous salt + folic acid tablets
June 7th, 2014 77 68
Drug classification system:-
The main purpose of having an
international standard is to be able to
compare data between countries.
Different classification systems : -
◦ Anatomical Therapeutic Chemical (ATC)
classification develop by Norwegian researchers.
serve as a tool for presenting drug utilization statistics
recommended by WHO for international comparisons
June 7th, 2014 69
◦ Anatomical Therapeutic (AT) classification developed by
the European Pharmaceutical Market Research
The EPhMRA classification system is used worldwide
by IMS (International Marketing Services) for
providing market research statistics to the
June 7th, 2014 70
Step 7:- Provide feedback of results
Prepare a scientific interpretation of the results
rather than a value judgment.
Success of any DUS depends on feedback of
results to prescribers, other hospital staffs
involved in the study and to administrative
The results can also be circulated to hospital
staff via newsletters or the hospital’s academic
June 7th, 2014 71
Step 8:- Develop and implement
If a drug use problem is identified the next step is to
consider how the problem can be addressed.
◦ Educational - educational meetings, development of
protocols, letters to individual physicians.
◦ Operational - modification of drug order forms,
development of stringent drug use policy, manual or
computerized reminders, prescribing restrictions,
formulary additions/deletions etc.
June 7th, 2014 72
Step 9:- Re-evaluate to determine
if drug use has improved
Drug use and prescribing patterns need to be
monitored to determine the success of intervention
Re-evaluation is usually done 3-12 months after the
introduction of the intervention
Collection of data as in original DUS
Should be a continuous process at regular interval
June 7th, 2014 73
Step 10:- Re-assess and revise the
Results of the previous DU studies help to
improve quality, efficacy and effectiveness
of future DU studies.
June 7th, 2014 74
Step 11:- Feedback results
Circulate results of the DUS
Obtain opinions about success of interventions
and improvement of drug use.
Analyze and act accordingly
June 7th, 2014 75
Reflects the number of drugs that account for 90% of
drug prescriptions and adherence to local or national
Can be applied at different levels
◦ Individual prescriber
◦ Group of prescribers
Gives a rough estimate of the quality of prescribing.
June 7th, 2014 76
Drug utilization evaluation
Drug utilization evaluation (DUE) is defined as an
authorized, structured, ongoing review of physician
prescribing, pharmacist dispensing and patient
DUE is ongoing, systematic process designed to
maintain the appropriate and effective use of drugs
Synonymous- Drug Utilization Review (DUR)
Medication use evaluation (MUE) is similar to
DUE but emphasizes on improving patient’s clinical
outcome and individual quality of life.
June 7th, 2014 77
Objectives of DUE:-
To ensure that drug therapy meets current
standards of care
To control drug costs
To prevent problem related to medication, ADRs
To evaluate effectiveness of drug therapy
To identify areas of practice that require further
education of practitioners.
June 7th, 2014 78
Classification of DUE:
A) Prospective DUE:-
◦ Involves evaluating a patient’s planned drug therapy
before a medication is dispensed.
◦ Pharmacists perform prospective reviews by assessing
prescription medication’s dosage and it’s directions
and reviewing patient information for possible drug
interactions or duplication of therapy.
June 7th, 2014 79
Typical criteria reviewed in prospective
studies include the following:-
Dosage form and routes of administration
Duration of therapy
Adverse drug reactions and drug interactions
June 7th, 2014 80
B) Concurrent DUE:-
◦ Performed during the course of treatment and involves
ongoing monitoring of drug therapy to ensure positive
Typical criteria reviewed:-
◦ Drug interactions
◦ High or low dosages
◦ Duplicate therapy
◦ Drug-disease interaction
◦ Over and under utilization
◦ Drug-age precautions
◦ Drug-gender precautions
◦ Drug-pregnancy precautions
June 7th, 2014 81
C) Retrospective DUE :-
◦ Simplest to perform since drug therapy is
reviewed after the patient has received
◦ Patients medical chart or computerized
records are screened to determine whether the
drug therapy met approved criteria.
June 7th, 2014 82
In retrospective studies, the criteria
Evaluation of indications and contra-indications
Monitoring high cost medicines
Comparison of prescribing between physicians
Cost to patient
Over and under utilization
Incorrect drug dosage
Adverse drug reaction
June 7th, 2014 83
Statistical application in Drug
Statistical Package for social science (SPSS) can be
Chi square test can be used to test the difference
between the proportions.
June 7th, 2014 84
The study of drug utilization in an evolving field.
The use of large computerized databases that allow
linkage of drug utilization data to diagnosis, subject to
some inherent limitations, is contributing to expand this
area of study.
Importance of drug utilization studies in
pharmacoepidemiology has been increasing due to their
close association to other areas like- public health,
pharmacovigilance, pharmacoeconomics and
June 7th, 2014 85
Successful research in drug utilization requires
multidisciplinary collaboration between clinicians,
clinical pharmacologists, pharmacists and
Without the support of the prescribers, this research
effort will fail to reach its goal of facilitating the
rational use of drugs.
Only by a combination of regulatory, informative and
educational actions, together with a general
improvement of the quality of in and out-patient
medical care in the National Health System, the use of
drugs can be more rational.
June 7th, 2014 86