Appropriate prescribing for older people

192 Pages·2013·5.63 MB·English

Appropriate prescribing
for older people
A.C. Drenth-van Maanen
ISBN
978-94-6191-746-1
Cover design and layout
Promotie In Zicht, Arnhem
Cover illustration
David Sipress
Printed by
Ipskamp Drukkers, Enschede
The work presented in this thesis was commissioned by the Expertisecentre
Pharmacotherapy in Older persons (EPHOR) and performed at the Geriatric
Department of the University Medical Center Utrecht in affiliation with the
Department of Clinical Pharmacy of the University Medical Center Utrecht.
EPHOR is funded by the Netherlands Organisation for Health research and
Development (ZonMw).
Financial support for publication of this thesis was kindly provided by:
Dr. G.J. van Hoytema Stichting
© 2013 A.C. Drenth-van Maanen
For articles published or accepted for publication, the copyright has been transferred to the
respective publisher. No part this thesis may be reproduced or transmitted in any form of by any
means, electronic or mechanical, including photocopy, recording or otherwise without permission
of the author, or when appropriate, the publisher of the manuscript.
Appropriate prescribing
for older people
Optimaliseren van farmacotherapie voor ouderen
(met een samenvatting in het Nederlands)
Proefschrift
ter verkrijging van de graad van doctor aan de Universiteit Utrecht
op gezag van de rector magnificus, prof.dr. G.J. van der Zwaan,
ingevolge het besluit van het college voor promoties
in het openbaar te verdedigen op
donderdag 20 juni 2013 des middags te 2.30 uur
door
Anna Clara Drenth-van Maanen
geboren op 29 april 1980
te Delft
Promotor
Prof.dr. A.C.G. Egberts
Copromotoren
Dr. P.A.F. Jansen
Dr. R.J. van Marum
Contents
Chapter 1 General Introduction 7
Chapter 2 Prescribing for older people receiving polypharmacy 19
2.1 Prescribing Optimization Method for Improving Prescribing 21
for Elderly Patients Receiving Polypharmacy: Results of
Application to Case Histories by General Practitioners
Chapter 3 Transitional pharmaceutical Care 45
3.1 Structured history taking of medication use reveals 47
iatrogenic harm due to discrepancies in medication histories
in hospital and pharmacy records
3.2 Use of a structured medication history to establish medication 63
use at admission to an old age psychiatric clinic: a prospective
observational study
3.3 Effect of a discharge medication intervention on the incidence 77
and nature of medication discrepancies in old patients
3.4 The effect of a transitional pharmaceutical care intervention 93
on the implementation of changes to patients’ medication
regimens into community pharmacists’ and general practitioners’
information systems
Chapter 4 Prescribing for patients with impaired renal function 111
4.1 R enal function assessment in older people 113
4.2 Adherence with dosing guideline in patients with impaired 129
renal function at hospital discharge
Chapter 5 General discussion 149
Chapter 6 From ‘Summary’ to ‘About the author’ 171
6.1 Summary 173
6.1 Samenvatting 177
6.1 Dankwoord 183
6.1 List of publications 189
6.1 About the author 191

1
General introduction
Chapter 1 General Introduction
8
Background
Appropriate prescribing refers to the results of a process of pharmacotherapeutic
1
decision-making that maximises net individual health gains within society’s
available resources.1 This definition implies that patient outcomes determine
whether prescribing has been appropriate or not. This differentiates appropriate
prescribing from rational prescribing which refers to the process of evidence based
prescribing decision making.2 If, for example, a patient develops a gastro-intestinal
bleeding on ibuprofen, prescribed for gout in the big toe, the prescription was
rational but turned out to be inappropriate for this individual patient.
The frequency of inappropriate prescribing, where the benefit-risk ratio results in
negative patient outcomes, increases in cases of irrational prescribing. In 2004,
Pirmohamed et al. showed that in England 6.5% of hospital admissions were
related to an adverse drug reaction.3 In 2008, Leendertse et al. published the results
of a similar study in the Netherlands, the HARM study.4 They found that 5.6% of all
unplanned hospital admissions were medication-related. Almost half (46%) of
these admissions were potentially preventable. The mean age of patients with a
potentially medication related hospital admission was 70 years.
Susceptibility of older people for inappropriate prescribing
Several risk factors for medication-related hospital admissions were identified
from the HARM study: impaired cognition, polymorbidity (≥4 diseases), dependent
living situation, polypharmacy (≥5 medications, chronically used), impaired renal
function, and nonadherence to medication regimen. The prevalence of all these
risk factors is highest among older people (Figure 1). For example, among older
people, the use of polypharmacy occurs frequently. In 2009, 39% of the Dutch
population between 65 and 74 years old, and more than half of all people over 75,
used five or more medications and almost 20% of people aged 75 years or above
were prescribed ten or more different medications.5 Although polypharmacy is
often indicated, it makes it more complex for physicians to balance the benefit-risk
ratio on the individual patient level, since outcomes of prescribing are more
difficult to predict due to increased frailty, polymorbidity, and interactions.
Causality of adverse events is also more difficult to determine in cases of
polypharmacy. Furthermore, in patients receiving polypharmacy, often multiple
prescribers are involved, who are insufficiently familiar with each other’s
prescribed medications.6 Older people are also at increased risk of inappropriate
prescribing because pharmacokinetics, pharmacodynamics, safety, and efficacy
change over time and may vary significantly between individuals of the same age.
For example, impaired renal function, which is present in up to 35.8% of people
aged 64 years or older, compared to 7.2% in people aged 30 or older,7 affects the
9
Chapter 1 General Introduction
pharmacokinetics of many medications significantly. In case of impaired renal
function, dose adjustments are required in medications that are excreted mainly by
the kidneys in order to prevent accumulation of these medications or their active
metabolites. Unfortunately, accurate detection of impaired renal function is
difficult in older people. Serum creatinine measurements are traditionally used to
assess renal function.8 However, since creatinine is a waste product of muscle
mass, it’s reliability declines in people with a deviating muscle mass, as is the case
in older, frail, malnourished or obese people. Furthermore, physicians often have
insufficient knowledge of which medications require dose adjustments in case of
impaired renal function.9-18
Finally, older people frequently transfer between health care settings. Each transition
creates an additional risk for medication errors due to conflicting information
between different sources and/or insufficient communication between health
care providers and patient. Several efforts have been accomplished to implement
transitional pharmaceutical care programs to improve continuity of pharmaceutical
care between health care settings.19-25
Prescription
Side effects of
medication
Benefit of Patient risk
medication factors*
Health care
system risk
factors*
Outcome
Appropriate Inappropriate
prescribing prescribing
Figure 1 Susceptibility of older people for inappropriate prescribing
10