1 Pharmacy Department, Queen's Hospital, Burton DE13 0RB; 2 Pharmacy Department, Aston University, Aston Triangle, Birmingham B4 7ET, UK
Received 19 January 2004; returned 18 April 2004; revised 29 April 2004; accepted 13 June 2004
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Abstract |
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Methods: Twelve hospitals were used in the study. Nine hospitals were selected and split into three cohorts (three high-scoring, three medium-scoring and three low-scoring) by their 2001 medicines management self-assessment scores (MMAS). An additional cohort of three electronic prescribing hospitals was included for comparison. MMAS were compared to antibiotic management scores (AMS) developed from a questionnaire relating specifically to control of antibiotics. FCEs and occupied bed-days were obtained from published statistics and statistical analyses of the DDD/100 bed-days and DDD/FCE were carried out using SPSS.
Results: The DDD/100 bed-days varied from 81.33 to 189.37 whilst the DDD/FCE varied from 2.88 to 7.43. The two indicators showed a high degree of correlation with r=0.74. MMAS were from 9 to 22 (possible range 023) and the AMS from 2 to 13 (possible range 022). The two scores showed a high degree of correlation with r=0.74. No correlation was established between either indicator and either score.
Conclusions: The WHO indicator for medicines utilization, DDD/100 bed-days, exhibited the same level of conformity as that exhibited from the use of the DDD/FCE indicating that the DDD/FCE is a useful additional indicator for identifying hospitals which require further study. The MMAS can be assumed to be an accurate guide to antibiotic medicines management controls. No relationship has been found between a high degree of medicines management control and the quantity of antibiotic prescribed.
Keywords: antibiotic use , defined daily doses , medicines management , electronic prescribing
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Introduction |
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The emergence of evidence based practice during the NHS policy reforms of the 1990s was part of the change to create a culture in which clinical governance drives individual hospital practitioners to examine their practice and compare it with their peers. Pharmaceutical care, the responsible provision of drug therapy for the purpose of achieving definite outcomes that improve a patient's quality of life3 defines the scope of pharmaceutical responsibility in the use of medicines. This was supplemented by the medicines management concept,4 which developed the theme of systems to control medicines usage from procurement, managed entry onto a hospital formulary through to prescribing review and use of clinical guidelines. In order to optimize the use of medicines, it is vital that therapeutic categories of medicines where there is high-volume and high-cost are reviewed. It has been established that antibiotics are often both high-volume and high-cost. In addition, it has been demonstrated5 that a large percentage of antibiotic use in hospitals is inappropriate.
Clearly, there is a requirement for multicentre clinical audit of antibiotic usage. However, in order to benchmark the use of antibiotics across the full spectrum of secondary care settings, a robust measure is needed which is independent of workload, in order that comparisons can be made. The UK Department of Health has recently allocated funding for each English hospital to use for promoting prudent use of antibiotics.6 This initiative will enable work to commence to improve targeted clinical pharmacy initiatives related to antibiotic use and also to begin to address collection of data from hospitals.
A large amount of therapeutic guidance712 has been published, which focuses on antibiotic resistance and the use of antibiotics in medicine. Issues examined include the use of formularies within hospitals, the process by which antibiotics are prescribed by junior doctors, susceptibility testing and the surveillance of resistant organisms. One report13 concluded that there was a lack of data on antimicrobial use in hospitals and that hospitals should install computerized systems for patient specific prescribing.
The European Society for Clinical Microbiology and Infectious Disease (ESCMID) established a study group on antibiotic policies (ESGAP) which in turn created a number of sub-groups to develop strategy related to the stewardship of antibiotics within European hospitals. This group produced a number of recommendations14 which include a commendation that measurement of antibiotic consumption should be carried out with regular benchmarking of figures and discussion between prescribers, pharmacists and infection specialists.
The purpose of any indicator of prescribing is to enable comparisons to be made over time. The comparison may be between individual prescribers, wards, specialties, hospitals or geographical groups of hospitals. Measures are not definitive but act as a focus for the commencement of review and should act as a stimulus for change.
The need for an international classification system for drugs has been recognized for many years.15 The Anatomical Therapeutic Chemical System (ATC), was developed by the Norwegian Medicinal Depot, in Oslo, by modification of an existing system that had been used by pharmaceutical market researchers in Europe. In addition to a robust classification system, it was necessary to develop a unit of measurement. The defined daily dose (DDD) was developed, also by the Norwegian Medicinal Depot as a unit of measurement for use in drug utilization studies. The ATC/DDD system, was recommended for international drug utilization studies by the World Health Organization (WHO) in 1981. The purpose of the ATC/DDD system is to act as a tool for drug utilization research so that the quality of drug usage will improve.
The DDD is defined16 as the assumed average maintenance dose per day for a drug used for its main indication in adults. A DDD is only assigned when a compound has been given an ATC code. All of the ATC codes and DDD data are published in the ATC Index.17 The DDD is not a reflection of a prescribed or recommended daily dose. It represents a unit of measurement to enable researchers to identify trends in consumption of medicines and to compare the exposure to specific medicines of population groups. The DDD is a compromise in that it is based on a review of doses used in a variety of countries. The DDD will normally be associated with a denominator to correct for workload variations. For hospital inpatients, the number of DDDs per 100 bed-days is normally used.
A study of the DDD system18 compared the approach of Europeans to undertaking drug utilization review with that of the North Americans which has focused more on review of individual prescribers and individual drug regimens in order to optimize patient treatments.
This study concluded that the DDD system would serve as a valuable additional tool for drug utilization studies. A further study carried out to evaluate DDD methodology19 concluded that calculation of the DDD was a valuable first step in measuring total drug use in a population, but that for more precise estimates of drug use, other techniques would also be required.
An antibiotic usage measure developed in 1998 within our group20 has been applied previously to the usage of quinolone antibiotics. In order to more fully evaluate the usefulness of this measure as a tool to compare antibiotic utilization, this study compares the recognized DDD/100 bed-days measure with the DDD/finished consultant episode (FCE) in a group of hospitals with a variety of medicines management strategies.
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Materials and methods |
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Antibiotic usage data were collected for systemic antibacterials (ATC category J01).
The number of occupied bed-days and FCEs for each Trust for 2001/2 was recorded from the Department of Health published Hospital Episode Statistics.
The hospitals were selected on the basis of their medicines management self-assessment scores arising from a nationally sponsored self-assessment exercise carried out at the beginning of 2001.22 This self-assessment consisted of six equally weighted domains of activity related to medicines management, with a high score being indicative of a high degree of control of medicines usage. The maximum possible aggregate score was 23. The six domains were as follows:
It was felt that the scores from this exercise would be indicative of the degree of control and influence over the general use of medicines and more specifically, antibiotics, and that high scores in this measure would be linked to low levels of antibiotic usage (divergent validity).
Reviewing the scores for hospitals in the West Midlands, it was possible to select three high-scoring hospitals (score >19), together with three medium-scoring hospitals (score >15 but <19) and a third group with lower scores (score <15).
In addition to these nine hospitals, it was felt that the three English hospitals that have fully implemented electronic prescribing systems would be used as a discrete comparator reflecting the potential importance of electronic prescribing systems in controlling medicines usage. The characteristics of the hospital trusts participating in this study are summarized in Table 1.
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The maximum possible score for this assessment was 22.
Statistical treatment
Data were entered into a flatfield database and analysed using the SPSS version 11 software package.
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Results |
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Figure 1 shows the correlation of the two prescribing indicators (Pearson correlation r=0.74). Figure 2 shows the correlation of the medicines management scores (Pearson correlation r=0.74).
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Discussion |
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The electronic prescribing group had the lowest mean usage of 3.5 DDD/FCE. It is likely that the use of a computerized prescribing system enhances good practice in prescribing by allowing pre-agreed stop dates to be programmed together with reminders about reviewing treatment and by providing a greater degree of formulary control. It would be valuable for a prospective study to be carried out to establish whether this is the case.
The total antibiotic usage figures for the 12 hospitals varied from 81.33 to 189.37 DDD/100 bed-days (mean 114.6). These findings can be compared with data from various European studies which found usage at 37.242.5,23 415124 and 2568.25 It may be that the much higher rates of antibiotic usage found in this study reflect a difference in the categories of patients that are included in secondary care activity data and how the English health care system operates.
The results do not show an association between a high score in either of the medicines management scores and a low value for the two prescribing indicators of antibiotic usage (Table 2). This lack of relationship leads to a conclusion that enhancing medicines management controls may not reduce antibiotic prescribing. These findings may indicate that antibiotic prescribing patterns within the study hospitals are subject to influences not embraced by the indicators employed. Such factors may include the morbidity of the hospital's catchment population, the casemix of patients treated, which in turn will be governed by the service profile offered by each hospital in terms of specialties and number of beds devoted to each specialty.
A morbidity profile for the catchment population of an individual hospital can be created from analysis of the Primary Care Trust of residence of patients treated and linking this to morbidity measures obtained from census data. This work is on-going. The influence of case-mix will influence the WHO measure (DDD/100 bed-days) to a greater degree than the DDD/FCE, since variations in case-mix, e.g. more surgical beds, would decrease the average length of stay within a hospital, whilst conversely a greater proportion of care-of-the-elderly beds will generally increase the average length of stay.
The FCE is more closely linked to individual inpatient exposure rates to antibiotics than bed-day numbers, as it is a measure of episodes of individual care. However, in some cases the episode of care may involve a number of consultants that can lead to it being counted as more than one FCE.
It is apparent that additional data are needed before conclusions about the quality of antibiotic usage in a specific hospital can be drawn. The specific profile of antibiotic use by therapeutic group for each hospital, together with local bacterial resistance data, would provide valuable comparative data. This will need to be linked to morbidity data and the usage data linked to activity will require monitoring over a number of years in order to determine the effects of control systems, be they electronic prescribing systems, utilization of pharmacists with a remit to change antibiotic prescribing habits or the establishment of multidisciplinary review teams. In order to maximize the opportunity for change to occur, pharmacists will need to work closely with microbiologists to influence prescribing habits.
The medicines management self-assessment score (MMAS) and the antibiotic medicines management score (AMS) showed a high degree of correlation (r=0.74), which demonstrates that the MMAS is a valid indicator of antibiotic medicines management arrangements.
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Conclusions |
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This study has highlighted the following points:
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Supplementary data |
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Footnotes |
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References |
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