Drug Utilization Evaluation of Analgesics Using Defined Daily Dose (DDD) and Defined Daily Dose/100 Bed-Days in the Surgical Department of a Teaching Hospital

Introduction

Pharmacoepidemiology is defined as, ‘the study of use and effects of drugs and other medical devices in large populations’. One of the applications of Pharmacoepidemiology studies is drug utilization evaluation.¹ Drug Utilization Evaluation (DUE) was defined by the WHO in 1977 as, “The marketing, distribution, prescription, and use of drugs in a society, with special emphasis on the resulting medical, social, and economic consequence.”^2,3

DUE was developed to review prescription patterns and drug usage. Conducting a carefully organized audit of drug prescriptions, as outlined by DUE, offers prospective advantages for patients, as well for the overall improvement of clinical practice, also provides proper feedback on results to the clinicians and helps in developing standard guidelines that define optimal/ideal drug use.⁴ The purpose of drug utilization evaluation is to guarantee the proper, safe, and effective use of medications in order to enhance patient health.⁵

To conduct a drug utilization evaluation, it is essential to have a classification system and a standardized unit of measurement for analysing drug usage. The Anatomical Therapeutic Chemical (ATC) system serves as the classification system and for the unit of measurement, Defined daily dose (DDD) is used. ATC classification system organizes the active components of a drug into a hierarchical structure consisting of five levels. The first level includes the fourteen main anatomical groups. The second level can be categorised as either pharmacological or therapeutic. Third and fourth levels encompass chemical, pharmacological, or therapeutic subgroups. The fifth level is dedicated to the specific chemical substance of the drug. In the ATC classification system, medicinal products containing two or more/ multiple active ingredients are classified as combinations and are assigned a different ATC code than those with a single ingredient (one active ingredient).⁶

An example of ATC classification and code: Morphine - N02AA01

The Defined Daily Dose (DDD) concept is one of the many approaches used for quantifying medication use. WHO defines DDD as ‘the assumed average maintenance dose per day for a drug used for its main indication in adults’, and is expressed in various units, e.g., grams or milligrams, which may differ by the route of administration.

The defined daily dose concept emerged to address the necessity of standardizing and converting readily available pharmacy inventory or sales data into clinically relevant units. Additionally, it serves the purpose of providing rough estimates of the population/number of individuals exposed to a particular drug or the class of drug.¹ DDD is independent of the price, currency, package size, and strength of a medicinal product. Within a particular population, it provides a gauge of exposure or therapeutic strength. DDD’s provide an approximate assessment of consumption rather than a precise measurement of actual drug consumption. DDD unit of measurement does not always correspond to the recommended or prescribed daily dose. The prescribed therapeutic doses for both individual patients and patient groups often deviate from the DDD because of factors like pharmacokinetics, individual traits such as age, ethnic differences, weight, gender, and the specific nature and degree of the medical condition.⁷ Implementing the Defined Daily Dose concept allows for examining the changes/trends in drug utilization over time, enables international-level comparison of drug use, and evaluates the effects of interventions and regulatory effects on prescribing patterns.

There are four different methods to express the Defined daily dose: i.e., DDD per 100-bed days, DDD/Patient, DDD per 1000 inhabitants per day, and DDDs per inhabitant per year. When the drug use by in-patients in a hospital is measured, the DDD per 100-bed days method is applied. DDDs are allocated only to the drugs that have already been assigned with an ATC code.⁸

DDD/100 bed-days can be calculated by using the following formulae -

• DDD = Number of items used × Amount of drug per item (mg) / WHO recommended DDD of drug
• DDD/100-bed days = Number of units administered in the study period (mg) / DDD (mg) × no. of days in the study period × no. of beds × Occupancy index × 100
• Occupancy index = Total inpatient service days for a period / Total inpatient bed count × no. of days in the study period ×100

Where,

The number of items used - is the units of drugs dispensed.

Amount of drug per item - is the dose of the drug.

Total inpatient service days for a period - is the total length of stay of each patient admitted to the ward during the study period.

The use of DDD in analgesics will aid in the detection of consumption and drug usage patterns. It could be used to evaluate and improve analgesic prescription by recommending practice guidelines in consultation with the physicians, to be assessable to them while they make clinical decisions. It can be used to compare the data of DDD in analgesics within the countries, between countries, regions, intra-departments, and other healthcare settings. If there is over or under-usage in comparison to recommended DDDs of the analgesics, the risk factors associated can be taken up for further studies.

Materials and Methods

A prospective observational study was conducted at a teaching hospital in Bengaluru, for a total period of three months from July 2022 to September 2022, after receiving approval from the Institutional Ethics Committee (Ref No. 532/L/11/12/Ethics/ESICMC &PGIMSR/Estt. Vol.-IV). Male and female surgery wards were visited every day during the data collection period and a total of 606 subjects above the age of 18 years, who were prescribed with systemic analgesics during their hospital stay were included in the study after obtaining informed consent from them. Patients prescribed with external dosage forms of analgesics and patients with severe illness and hemodynamically compromised condition were excluded from the study. Demographic data and the prescribed drug data of the subjects were collected using the subject’s case sheets and treatment charts.

The data obtained was entered into the MS Excel sheet and descriptive statistical analysis was performed. The demographics data was analysed and displayed in the form of graphs, the prescription pattern of analgesics was displayed in the form of a table and the DDD/100 bed days of analgesics was calculated by using the formula containing the Defined daily dose and ATC code.

Results

Analysis of Demographic Data

A total of 606 subjects were included in the study. The majority of subjects in the Department of General Surgery were males [360 (59.4%)] and the female subjects were 246 (40.6%) (Figure 1). The majority of male subjects were in the age group of 48-57 years (26.14%), with a mean age of 46.88±14.75 years and the majority of the female subjects were in the age group of 38-47 years (36.17%), with a mean age of 44.96±12.16 years (Figure 2).

The minimum and maximum lengths of stay were two days and 31 days, respectively. The average length of stay was observed to be 7.19 ± 4.39 days. The majority subjects’ length of stay was between 2-6 days in both male and female wards (Figure 3).

Prescription Pattern of Analgesics in the General Surgery Department

A total of 606 subjects’ medication details were collected from the Department of General Surgery during the study period. Paracetamol 1g IV was observed to be the most used analgesic in this department with the units consumed being 4811 (48.63%). Aceclofenac 100 mg oral drug was the least used analgesic with units consumed at 29 (0.29%) (Table 1).

Analgesic Drug Consumption Based on DDD and DDD/100 Bed-days

In Table 2, the ATC-DDD classification of the analgesics with ATC/DDD codes is shown. The DDD may not necessarily be the same as the WHO-recommended dose. ATC code is available for Paracetamol, Tramadol, Diclofenac, Aceclofenac, Pregabalin, and the combination analgesics Paracetamol and Tramadol for which WHO recommended DDD is also provided. As the ATC code and WHO recommended DDD of these analgesics were available, the DDD/100 bed-days for these analgesics were computed. The Occupancy index was 0.55 during the study period of 90 days, with 110 as the number of bed count in the surgery department. Using these parameters, along with the number of units administered during the study period and the WHO recommended DDD, the DDD/100 bed-days for each analgesic with ATC code was calculated.

Consumption of analgesics in the Surgery department, measured based on DDD/100 bed days is shown in Table 2. It can be noted that Paracetamol 1g IV was the most consumed analgesic drug (29.43), followed by Paracetamol 500 mg oral (10.61), Diclofenac 50 mg IV (3.315), Diclofenac 75 mg IV (1.198) and Tramadol 50 mg IV (1.007).

Discussion

This observational study was conducted to assess the drug utilization evaluation of analgesics in the Surgical department of a teaching hospital.

The subjects were categorized based on age and gender. Out of 606 subjects who were part of the study, the majority were males [59.4% (n=360)], a contrast to the findings of the study conducted by Chaudhary et al. where female subjects were more predominant compared to males.⁹ The majority of male subjects were from the age group 48-57 years (26.14%), with a mean age of 46.88±14.75 years and the majority of the female subjects were from the age group 38-47 years (36.17%), with a mean age of 44.96±12.16 years, similar to Chaudhary et al. study. The average length of stay for subjects was observed to be 7.19±4.39 days.⁹ The majority of the subjects’ length of stay was between 2-6 days in both male and female wards. The average length of stay observed in our study coincides with the study reported by Patel KM et al.¹⁰

The prescription pattern of analgesics in the General Surgery department was assessed and it was identified that a total of 9892 units of analgesics were consumed by the subjects during their hospital stay. It was measured that Paracetamol [85.37%, (n=8445)] was the most consumed analgesic drug in different dosage forms. This observation was similar to the study conducted by Dawane et al.¹¹ Aceclofenac 100 mg oral drug was the least used analgesic at 0.29% (n=29). Only one analgesic combination drug was prescribed to the subjects during our study period which was Paracetamol with Tramadol [0.33%, (n=33)]. This observation was unlike the Dawane et al. study, which reported four different analgesic combination drugs prescribed to the subjects during their hospital stay.¹¹ In non-opioid analgesics, Paracetamol was observed to be utilized the most in our study, and among the opioid analgesics, Tramadol [3.83%, (n=379)] was the most utilized analgesic; this observation was similar to the study conducted by Patel K M et al.⁹ Diclofenac [5.28% (n=523)] was found to be the most utilized drug among the NSAID group of analgesics which was contrary to the study conducted by Jayakumari et al., where it was observed that Aspirin was the most consumed NSAID analgesic.¹² Consumption of analgesics measured based on DDD/100 bed days reflects larger use of Paracetamol, Tramadol, and Diclofenac in parenteral (IV) form than in oral dosage form. Analgesics like Aceclofenac, Pregabalin, and the combination drug (Paracetamol and Tramadol) were consumed in lesser quantities.

One of the limitation of this study was that the study population did not include pregnant women and children.

Conclusion

This study analysed the prescription pattern of various analgesics in the Surgery department. Drug utilization evaluation of analgesics in the Surgery department of the hospital, based on DDD and DDD/100 bed-days measurement showed that parenteral forms of analgesics like Paracetamol, Tramadol, and Diclofenac were consumed more often than the oral dosage forms of these drugs. The study also revealed that the consumption of drugs like Tramadol and Pregabalin in the oral dosage forms was less in the hospital included in the study, which shows rationality in the use of controlled drugs. Applying DDD, a technical unit of measurement of drugs at regular intervals in a hospital will help in examining the changes in drug utilization. Comparison of usage of drugs between departments in the hospital, and between various hospitals in a region can also be undertaken. Such studies can also document the relative therapy intensity of various groups of drugs and evaluate the regulatory effects and effects of interventions on prescribing patterns.

Conflict of interest

Nil

Acknowledgment

We are grateful to the staff, faculties, and subjects of the Department of General Surgery and the Hospital for their assistance in helping us get the consumption data of analgesic drugs.

Disclaimers: The views and opinions expressed in this article are solely our own and do not necessarily reflect the official position of ABMRCP or any of its funders.