How to set up a Drug Utilization Study

Setting up a Drug Utilization Study

When setting up a drug utilization study, the questions to be answered and the study objectives should be defined. It is also important to decide whether the study will be a onetime activity (research project) or an ongoing monitoring program.

Once it has been decided to perform a drug utilization study, it must be decided which data source or sources to use. In many countries, the sources are limited and the question is; Which sources do we have and how can they be used?

It is important to tailor the choice of data source to the question that needs to be answered. Do we need to know:

  • How much is used of certain drugs in a country, region, hospital or in a primary care setting?
  • What is the drug used for (indication)?
  • How is it used (dose and duration of treatment)?
  • Who are using it (age, gender)?

There are still many countries where drug utilization data are not easily available. But in nearly all countries there will be systems and structures that can be used to set up a drug utilization study.

Independent of the data source available, the steps for setting up a drug utilization study, or rather; how to proceed to convert available drug data into drug utilization data is more or less the same. The key issue of applying the ATC/DDD methodology is to transfer a list of medicine packages into a structured list of ATC classified medicines, and the use/sales in a respective number of packages into a number of DDDs.

Check the different steps in setting up a DU study!

An example from a hospital setting

The aim is to compare the use of antibacterials between different departments in different hospitals. Such research questions are often solved by setting up a cross-sectional study. This will give a ‘snapshot’ of drug use at a particular time – over a year, a month or a day for example. Cross-sectional studies might be used for comparison with similar data collected over the same period in a different country, health facility or ward, and could be drug-, problem-, indication-, prescriber- or patient-based. Alternatively, a cross-sectional study can be carried out before and after an educational or other intervention. Studies can just measure drug use, or can be used to assess drug use against guidelines or restrictions.

In this example study, we will monitor the prescribed antibiotics in similar hospital departments in three different hospitals over a month. No computerized records are available, and we have to collect the data manually. This can be done either from the dispensary if available, by using forms specifically designed for the study to be filled in by the nursing staff, or to collect the patient journals available. The following steps should be taken to edit the information from the dispensary, medication forms or patient journals into drug utilization data:

  • Create a total list of the antibiotic products that are used. The list must include information of the particular pharmaceutical form (i.e. tablet, injection solution etc) and strength of the product (i.e. mg per tablet). Go to chapter 8: Start using ATC/DDD
  • The active ingredient/s of each package of the prescribed antibiotics (as defined by pharmaceutical form and strength) must be listed and the correct ATC code added. Go to chapter 8: Start using ATC/DDD
  • Number of defined daily doses must be calculated for each package size of the prescribed antibiotics. Go to chapter 8: Start using ATC/DDD
  • If there are products with no official ATC codes or DDDs assigned, a request should be sent to the WHO Collaborating Centre for Drug Statistics Methodology, see ATC Codes  and DDD Application
  • Number of prescribed packages (or units) in the period per hospital department should be linked to this product list and total number of DDDs can be calculated

Example of edited records of drug utilization data for two packages of antibacterials:

Click here to visualize the example

The yellow part of the list represents the basic elements of the drug list/product registry with ATC and DDD information added at the package level (only two packages included, but multiplied in this list of drug utilization data where each line represents a hospital department). The drug list with correct ATC and DDD information can and should be reused for other studies and the ultimate aim is to have a drug list/product registry available at the national level, Go to chapter 8: Start using ATC/DDD  .

The blue part of the list represents the collected drug utilization data in number of packages used per hospital department. Preparing this list in a suitable spreadsheet, number of DDDs used in each department in the period can be calculated (Number of DDDs per package x Number of packages).

The ATC group levels in the hierarchy can be added, and the data can be aggregated and comparisons can be made on various ATC levels:

Example cefotaxime (See ATC Structure):

J --------------(ATC 1st level) -----------Antiinfectives for systemic use
J01 -----------(ATC 2nd level) -----------Antibacterials for systemic use
J01D ---------(ATC 3rd level)------------Other beta-lactam antibacterials
J01DD -------(ATC 4th level)------------ Third-generation cephalosporins
J01DD01 -----(ATC 5th level)------------Cefotaxime

Drug utilization figures should ideally be presented using a relevant denominator for the health context. In the hospital setting, this would be the number of patients or number of bed days in the setting and period monitored. Description and calculation of the most common indicators such as DDD/patients and DDD/100 bed days, see chapter 4  .

Use of the basic steps in the example above in other settings

Similar lists as described above, with ATC/DDD information added at the package level (yellow part of the table) can be prepared based on e.g. procurement lists, lists from wholesalers, sales data from pharmacies or medical practices. Number of packages sold can then be organized according to ATC groups and the amount can be calculated in DDDs.

 

Further descriptions of monitoring of drug use patterns and quality control of drug use is described in in the guidebook Introduction to Drug Utilization Research.