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The development of standard values for the WHO drug use prescribing indicators

Isah AO*, Ross-Degnan D, Quick J, Laing R, Mabadeje AFB,

INRUD - Nigeria1, Support Group2; DAP - WHO3.

*Department of Medicine, University of Benin Teaching Hospital, Benin City, Nigeria

 

 

The introduction of the drug use indicators by the WHO offers a useful tool for assessing drug use practices in various settings. One major set back in this effort is the lack of reference standard values.

This study outlines a method for developing standard values for the core drug use prescribing indicators using survey - derived morbidity mix and treatment guidelines developed by a panel of health care providers.

10 health care facilities (HCF) were selected randomly from two states in Nigeria (Edo and Delta). A minimum of 100 records of patient encounters were obtained from each HCF by systematic sampling. The morbidity profile - proportion and severity of the major clinical entities - were determined after a detailed review of the clinical presentation by a consensus panel. The most appropriate treatment for the identified clinical entities were provided and values assigned to the indicator variables following exhaustive discussion by an experienced team of health care providers (each with more than 10 years experience in their respective discipline).

The standard indicator values were then derived by summing the products of the proportion of cases and the value assigned to the indicator variable of each clinical entity.

1109 encounters were evaluable. The predominant diseases were malaria (24.9%), ARI (11 .9%), skin disorders (7.0%), trauma (6.8%), non specific fevers (4.5%), diarrhoea (4.0%), miscellaneous disorders (23.0%) and encounters with multiple diagnosis (17.9%). The derived standards were as follows: Average no. of drugs per encounter (1.6 - 1.8); percentage encounters with injections (13.4 - 24.1) and antibiotics (20.0 - 26.8). The maximum value of 100.0% each were assigned to the percentages of drugs prescribed in generic name and those on the essential drug list.

The effective use of these standards as a tool for intervention is likely to further promote rational use of drugs amongst health care providers.

The support of DAP-WHO is gratefully acknowledged.

 

 

Introduction

The introduction of the Drug Use Prescribing Indicators following the collaborative work by the members of the International Network for Rational Use of Drugs (INRUD) and the DAP-WHO1 may be regarded as one of the most notable achievements in the orchestrated effort at promoting rational use of drugs since the 1985 WHO-sponsored Nairobi meeting2 . The indicators provided objective and reproducible measures of the effectiveness and efficiency of drug use and enabled comparison of drug use practices at facility, regional and inter-country levels. Furthermore, it possessed a potential to serve as a strong tool for supervision and monitoring of drug use practices. It could also be used for peer group or self audit of prescribing performance and enable identification of non-compliant prescribers by analysis of prescriber coded data.

A major limitation in realising some of these potentials is the absence of reference values3 which would serve as a yardstick to assess the prescribing practices as well as evaluate interventional and supervisory efforts. Furthermore, the absence of an acceptable reference value for these indices makes arguments for rational use of drugs abstract and difficult to appreciate. The setting of target values will be geared to improving therapeutic performance of prescribers, thus the quality of care.

The core prescribing indicators include: (1) average number of drugs per encounter; (2) percentage encounter prescribed injections; (3) percentage encounter prescribed antibiotics; (4) percentage of drugs prescribed with generic name;(5) percentage of drugs prescribed in the essential drugs list or formulary.

The latter two have a desirable optimal value of 100% which could be regarded as the reference values. However the other indicators will depend on the clinical case mix, since this will determine the volume and mix of the prescribed drugs4. A logical step therefore is to ascertain the morbidity pattern in the setting for which the standard is being developed. Subsequently, the therapeutic guidelines for treatment of the various disease entities could be used to infer the acceptable drug treatment hence the standard indices.

This study presents an approach to developing reference standard values using a survey-derived morbidity mix and standard treatments of the diseases.

 

 

Objectives

The objective of this study is to develop standard values for the drug use indicators using:

(1) the morbidity profile (clinical case mix) of the locally occurring cases obtained from medical records; and

(2) standard treatment guidelines from which values for the indicator variables will be assigned.

 

 

Methods

The procedure used for the development of standard values for prescribing indicators will be presented under the following three headings:

1. Establishment of morbidity profile

2. Formulation of drug treatment guidelines for highly prevalent diseases identified in (1).

3. Development of standard values for the drug use prescribing indicators using (1) & (2).

Establishment of the morbidity profile

The study was carried out in two Nigerian States - Edo and Delta, located in the Southwestern region (Fig 1). The study was carried out after consultations with and approval from the States' Ministries of Health.

Data collectors were trained over a three day period in the week preceding the study. Ten health care facilities were selected by stratified random sampling using the health zones as strata from the two study states (Fig. 1).

In each facility an initial assessment of the medical record system was carried out during the pre-study visits to ensure a true representation of the cases seen. This was followed by the selection of a minimum of 100 outpatient case records per facility by systematic random sampling. Antenatal, postnatal or well baby attendance where illness was not recorded were excluded. Facilities without a proper recording system were also excluded.

Information relating to presenting clinical symptoms and signs, all recorded diagnosis (ICD-9) including features suggesting their severity, results of laboratory investigations and drugs prescribed were obtained using a standard form.

A review panel of four clinicians was set up to adjudicate on these features and present a consensual diagnosis. Guidelines were established and used to determine the severity of the illness.

Development of Standard Treatment Guidelines

Following the outlining of the morbidity profile, a panel of experts comprised of clinicians/prescribers with not less than 10 years of post qualification experience assembled to discuss the preferred treatment for the identified major diseases. Reference was made to specific national treatment protocols, WHO manuals and other national treatment guidelines.

The panel addressed the most prevalent cases found during the morbidity survey and reached a consensus on the most appropriate treatment. From this, the appropriate indicator values for the disease category was assigned.

Analysis of data

A frequency distribution was constructed from cases by type and apparent severity. Diseases with a frequency of greater or equal to 4.0 % were identified and handled as 'single disease' entities. Those conditions with lower frequency values were grouped into a 'miscellaneous' category for ease of handling. Cases where more than one diagnosis were made were grouped into a 'multiple disease' category.

Particular note was also taken of bacterial diseases requiring antibiotic therapy. Thus, diarrhoeal and skin diseases and those in the miscellaneous and multiple categories were subclassified where appropriate to accommodate the need for antibiotics.

Derivation of standard values for the prescribing indicators

The standards were then derived by obtaining the sum total of the product of the proportion of cases and the indicator values assigned to the treatment of the disease category i.e.

Standard Value for a prescribing indicator = sum of (proportion of case * indicator value assigned).

 

 

Results

A total of 1,140 cases (530 Males, 610 Females 610 aged 1 week 80 years) were studied in the ten study centres.

Table 1 shows the morbidity pattern - types and case severity - with the identified main clinical problems (4.0%). Malaria was the most prevalent disease identified in outpatient consultations accounting for 24.9 % of single cases diagnosis. Co-morbidity with malaria and ARI accounted for 9.4 and 2.8% respectively. This was taken into consideration in the subclassification of the multiple disease category.

Table 1: Morbidity profile an d severity assessment (%)

Diseases % Frequency Severity assessment
Mild Mod - Severe
MALARIA 24.9 22.8 2.1
ARI 11.9 9.5 2.4
SKIN 7.0 4.3 2.7
TRAUMA 6.8 5.4 1.4
FEVER (NOS) 4.5 4.1 0.4
DIARRHOEA 4.0 1.5 2.5
MISCELLANEOUS 23.0 10.0 13.0
MULTIPLE 17.9 12.2 5.7
TOTAL 100.0 69.8 30.2

 

Table 2: Standard values for the who prescribing indicators single diagnosis category

Diagnosis/ clinical problems

Case severity

Panel recommended values

total no. of drugs

no. of injections

no. of antibiotics

MALARIA

A

2

0

0

B

2*

1*

0

ARI

A

1

0

0

B

2*

1

1

FEVER (Nos)

A

1

0

0*

B

2

0*

1

DIARRHOEA

A

1

0

0*

INFECTIVE

B

2

1*

1

NON-INFECTIVE

A

1

0

0

B

1

1

0

SKIN

A

1

0

1

BACTERIAL

B

1*

0*

1

SKIN

A

1

0

0

NON-BACTERIAL

B

1*

0*

0

TRAUMA

A

1

0

0

OPEN

B

2*

2

1

TRAUMA

A

1

0

0

CLOSED

B

1*

1

0

A = MILD

B = MODERATE T0 SEVERE

* = ADDITIONAL DRUG MAY BE REQUIRED

The proportion of cases and the assigned values for the single diagnosis category and the sum of their product are shown in Table 3. The miscellaneous single and multiple diagnosis were handled in similar manner taking into consideration the sub-groups requiring antibiotics. The derived standards are shown in Table 4.

 

Table 3: Summary of indicator values

Category

No. of drugs prescribed

Injections

Antibiotics

min

max

min

max

min

max

Single diagnosis
- six top diseases 0.887 0.954 0.082 0.119 0.090 0.141
- miscellaneous 0.254 0.348 0.011 0.053 0.036 0.047
multiple diagnosis 0.450 0.487 0.041 0.069 0.074 0.080
indicator standards 1.591 1.789 0.134 0.241 0.200 0.268

 

Table 4: Derived standard values for the WHO prescribing indicators

Indicators Standard values
1. Average number of drugs per encounter 1.6 - 1.8
2.Percentage of encounters with an antibiotic prescribed 20.0 - 26.8
3.Percentage of encounters with an injection prescribed 13.4 - 24.1
4.Percentage of drugs prescribed by generic name 100.0
5.Percentage of drugs prescribed from the essential drug list or formulary 100.0

 

 

 

Conclusion

This study highlights a reproducible method for developing standard values for the WHO prescribing indicators. Its use is likely to enable a more focused approach in efforts to promote rational use of drugs.

However, standards for the indicators may not be globally generalized since the clinical case mix, which is the main determinant of the indices, may be influenced to varying degrees by other local factors.


 

References

1. WHO: How to investigate drug use in health facilities. Selected drug use indicators WHO/DAP/93 .1 World Health Organisation Geneva 1993.

2. WHO: The rational use of drugs. Report of the Conference of Experts, Nairobi, 25--29 November 1985. Geneva, World health Organisation,1987.

3. Hogerzeil HV Promoting rational prescribing: an international perspective. Br J Clin Pharmac 1995;39:1 - 6.

4. Col NF and O'Connor RW Estimating worldwide current antibiotic usage: report of Task force 1. Review of infectious diseases 1 987;9(Suppl.3):S232-43.