E-drug: Antimicrobial consumption measures (cont)
---------------------------------------------
Dear Faustine,
Your question concerning looking at antimicrobial consumption and
relating it to antimicrobial resistance in a referral hospital is a
very interesting question but a difficult one to answer. There is no
standardised methodology and very few studies have actually been done
in this area. What methods you use depend partly upon what the
objective of your study is. For example, is your interest to
demonstrate a relationship between consumption and resistance in
order to use the information to raise awareness of the issue of
antimoicrobial resistance and
irrational use? Alternatively, are you interested to find out about use and
resistance in order to use the information when developing standard
treatment guidelines? Another objective may be to evaluate an
intervention aimed at changing drug use behaviour and relating this
to resistance patterns.
With regard to measuring antimicrobial use, the commonest method used
(in association with measuring resistance also) is to measure defined
daily dose (DDD), as you rightly point out. However, you would need
also to define the denominator e.g. defined daily dose per 100 bed
days. This method is okay if you want just to relate consumption with
resistance (although there are problems in relating the two, as
discussed later). However DDD does not tell you anything about the
appropriateness of use since it does not take diagnosis into account.
In order to inform the process with regard to developing standard
treatment guidelines or evaluating behaviour change with regard to
antimicrobial use, you will need to measure antimicrobial consumption
in terms of the proportion of cases of a specified disease treated
with specific antimicrobials and in what doses. You would also need
to make an assessment of whether the antimicrobial use conformed to
standard guidelines. Drug utilisation review or evaluation (DUR/DUE)
are detailed ways of looking at drug use related to specific
diagnoses.
With regard to measuring antimicrobial resistance, two things that
need careful consideration are what organisms are you going to look
at (dependent upon the disease(s) to be investigated) and what
denominator will you use (cases versus isolates). In order to relate
resistance and use with a view to changing drug use behaviour and
consequent resistance, it is preferable to monitor resistance
according to individual cases and not just isolates. Furthermore, it
is important to distinguish between hospital-acquired infections and
community-acquired infections. Unfortunately, many laboratories
monitor resistance related to:
(1) number of isolates, not cases, and
(2) passively rather than actively (i.e. not distinguishing between
hospital-acquired and community-acquired isolates).
Without such distinctions, it is difficult to relate resistance to use or to
decide, for example, what antimicrobials should be recommended to
treat what infections in standard treatment guidelines.
A final problem with regard to relating resistance and use concerns
the fact that antimicrobial resistance patterns now are likely to be
associated with antimicrobial use patterns of some years ago. When
trying to relate the two data sources, one makes the assumption that
use patterns now are similar to those of some years back. This may
not be the case for nosocomial infections in hospitals, but may well
be so for community acquired infections. Hence the importance of
monitoring resistance in community-acquired infections.
In summary, relating use and resistance in a meaningful way to inform
the policy process is very important and worthwhile, and I would
encourage you in your project. However, there is no standardised
methodology yet, although WHO is at present working on guidelines on
how to do antimicrobial resistance surveillance from an
epidemiological point of view so as to be better able to relate
resistance to drug use patterns. With regard to detailed analysis of
drug use, there is a wealth of information about investigating drug
use. "Managing Drug Supply" published in 1997 by Kumarian press inc.
of 14 Oakwood Avenue, West
Hartford, Connecticut 06119-227, USA, gives a good summary of drug
utilisation review or evaluation.
Regards,
Kathy
Kathy Holloway, Medical Officer,
Dept. Essential Drugs and Medicines Policy,
World Health Organisation, Geneva
Tel: +41 22 791 2336
Fax: +41 22 791 4167
email: hollowayk@who.int
......................................................................
..........
......................................................................
..........
..............................................................
.
Dr. Kathleen Holloway,
Medical Officer,
Policy, Access and Rational Use,
Essential Drugs and Medicines Policy,
World Health Organisation,
20 Avenue Appia, Geneva 27,
Switzerland CH-1211.
Tel: +41 22 791 2336
Fax: +41 22 791 4167
email: hollowayk@who.int
http://www.who.int
--
Send mail for the `E-Drug' conference to `e-drug@usa.healthnet.org'.
Mail administrative requests to `majordomo@usa.healthnet.org'.
For additional assistance, send mail to: `owner-e-drug@usa.healthnet.org'.