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\begin{document}

\title{Associations between potentially inappropriate prescribing and increased
number of medications with post-discharge health outcomes among
geriatric rehabilitation inpatients: RESORT study}



\author[1]{Alemayehu Mekonnen}%
\author[2]{Esmee Reijnierse}%
\author[2]{Cheng Soh}%
\author[2]{Kwang  Lim}%
\author[2]{Andrea Maier}%
\author[3]{Elizabeth Manias}%
\affil[1]{Deakin University Faculty of Health}%
\affil[2]{The University of Melbourne}%
\affil[3]{Deakin University}%


\vspace{-1em}



  
  \date{May 29, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Aims: Older adults are vulnerable to medication-related harm mainly due
to high use of medications and inappropriate prescribing. This study
aimed to investigate the associations between inappropriate prescribing
and number of medications identified at discharge from geriatric
rehabilitation with subsequent post-discharge health outcomes. Method:
REStORing health of acutely unwell adulTs (RESORT) is an observational,
longitudinal cohort study of geriatric rehabilitation inpatients.
Potentially inappropriate medications (PIMs) and potential prescribing
omissions (PPOs) were measured at acute admission, and at admission and
discharge from geriatric rehabilitation, using version 2 of the
STOPP/START criteria. Results: 1890 patients (mean age 82.6 \selectlanguage{ngerman}± 8.1 years,
56.3 \% females) were included. The use of at least 1 PIMs, or PPOs at
geriatric rehabilitation discharge were not associated with 30-day and
90-day readmission and 3-month and 12-month mortality. Central nervous
system (CNS)/psychotropics and fall risk PIMs were significantly
associated with 30-day hospital readmission (adjusted odds ratio (AOR)
1.53; 95\%CI 1.09\selectlanguage{english}-2.15), and cardiovascular PPOs with 12-month mortality
(AOR 1.34; 95\%CI 1.00\selectlanguage{english}-1.78). Increased number of discharge medications
was significantly associated with 30-day (AOR 1.03; 95\%CI 1.00\selectlanguage{english}-1.07)
and 90-day (AOR 1.06; 95\%CI 1.03\selectlanguage{english}-1.09) hospital readmissions. The use
and number of PPOs (including vaccine omissions) were associated with
reduced independence in instrumental activities of daily living scores
at 90-days post geriatric rehabilitation discharge. Conclusion: The
number of discharge medications, CNS/psychotropics and fall risk PIMs
were significantly associated with readmission, and cardiovascular PPOs
with mortality. Interventions are needed to improve appropriate
prescribing in geriatric rehabilitation patients to prevent hospital
readmission and mortality.%
\end{abstract}\selectlanguage{ngerman}%



\sloppy


\textbf{Introduction}

Medication-related harm is an underdiagnosed problem in
Australia,\textsuperscript{1} costing the Australian healthcare system
about A\$1.4 billion per annum.\textsuperscript{2} The older population
(aged [?]65 years) is particularly vulnerable to medication-related harm
due to their advanced age, multimorbidity and increased use of
medications (polypharmacy).\textsuperscript{3} Increased medication use
is, in turn, linked to potentially inappropriate prescribing
(PIP).\textsuperscript{4,5} Potentially inappropriate prescribing
comprises the use of potentially inappropriate medications (PIMs) where
the risks outweigh clinical benefits and potential prescribing omissions
(PPOs), which is the failure to prescribe medications that provide
benefits.\textsuperscript{6}Recent reviews have shown that PIPs are
common among older adults in diverse healthcare settings, and are
associated with medication-related hospitalisation, adverse drug
reactions, adverse drug events, and functional
decline.\textsuperscript{7,8} A systematic review and meta-analysis of
63 included studies has shown that patients using at least 1 PIM in the
inpatient setting (compared with non-users) were associated with a 91\%
increased odds of medication-related hospital admission, and 60\%
increased odds of dependency in at least 1 activity of daily
living.\textsuperscript{7}

Multiple screening tools are available to detect and reduce PIPs among
older adults, such as the Screening Tool of Older Person's Prescriptions
and the Screening Tool to Alert doctors to Right Treatment (STOPP/START)
criteria, and the Beers criteria.\textsuperscript{9} These are also the
tools commonly used in research in Australian healthcare
setting.\textsuperscript{10-14} PIP, according to STOPP/START criteria,
have been investigated mainly through retrospective analysis in acute
care settings,\textsuperscript{11-13} with high variability in
prevalence estimates between care transition points. A clinical audit of
electronic medical records of 249 older people from an Australian
teaching hospital found 51\% were exposed to at least 1 PIM at hospital
admission and, this prevalence was reduced to 37\% at
discharge.\textsuperscript{12} In contrast, another Australian study
found an increase in the prevalence of PIM use from hospital admission
to discharge (54.8\% vs 60.8\%).\textsuperscript{13} In addition,
results from previous international studies on the influence of
inappropriate prescribing on post-discharge health outcomes are mixed.
While some studies highlighted the presence of PIMs/PPOs was
significantly associated with potentially preventable medication-related
hospital admissions,\textsuperscript{15}repeated hospital admissions and
mortality,\textsuperscript{16} other investigations did not confirm
these findings with respect to post-discharge health outcomes, including
rehospitalization and mortality either in acute
care\textsuperscript{17-19} or geriatric rehabilitation
settings.\textsuperscript{20} Moreover, evidence is limited on PIM/PPO
prevalence as well as their associations with post-discharge health
outcomes in patients admitted to and discharged from geriatric
rehabilitation settings.

The purpose of this study was to assess the prevalence of PIM and PPO
use at transitions of geriatric rehabilitation care (acute admission,
admission to and discharge from geriatric rehabilitation) and to
investigate the associations between PIMs, PPOs, and number of
medications identified at discharge from geriatric rehabilitation with
subsequent post-discharge health outcomes, including hospital
readmissions and mortality.

\textbf{Methods}

Study design and setting: RESORT (REStOring health of acutely unwell
adulTs) is an observational longitudinal study cohort of patients
admitted to the Royal Melbourne Hospital (Victoria, Australia) for
geriatric rehabilitation (recruitment commenced October 16, 2017, and
ended March 18, 2020), comprising a total of 1890 older adults. A
description of the cohort, methods, and design in the RESORT study is
available elsewhere.\textsuperscript{21,22} Briefly, patients on the
geriatric rehabilitation wards of the Royal Melbourne Hospital,
Melbourne, Australia, completed a standardized comprehensive geriatric
assessment at both admission and discharge by a multidisciplinary team
inclusive of physicians, nurses, physiotherapists, and occupational
therapists, and followed up at 3 months post-discharge via phone
interviews. Written informed consent was obtained by all patients or a
nominated proxy. Patients were excluded if they were receiving
palliative care at admission, were transferred to acute care prior to
consenting to the study or lacked both the capacity to provide informed
consent and a nominated proxy. The study was approved by the Melbourne
Health Human Research Ethics Committee (HREC/17/MH/103).

Data sources and collection: Age, sex, and length of stay were obtained
from medical records. Other demographic characteristics (e.g., current
living situation, living status, primary language, walking ability) were
obtained from a survey completed by the patient and/or carer. The
primary reason for hospital admission was extracted from medical records
and grouped into musculoskeletal, neurological, cardiorespiratory,
infection and other (including gastrological, urology, hematology,
ophthalmology, vascular, psychiatry related conditions, cancer, and
metabolic disorders) by trained researchers. Physicians assessed
morbidity using the Charlson Comorbidity Index (CCI)\textsuperscript{23}
and the Cumulative Illness Rating Scale (CIRS).\textsuperscript{24} CCI
and CIRS scores ranged from 0-37 and 0-56, respectively. Frailty was
assessed by physicians using the Clinical Frailty Scale
(CFS),\textsuperscript{25} ranging from 1-9, with greater scores
indicating a higher level of frailty. Cognitive impairment assessment
was completed by physicians and was defined as a dementia diagnosis
captured by the CCI, CIRS, or medical records, or a score on the
Standardized Mini-Mental State Examination of \textless{} 24
points,\textsuperscript{26} Montreal Cognitive Assessment score
\textless{} 26 points,\textsuperscript{27} or the Rowland Universal
Dementia Scale \textless{} 23 points.\textsuperscript{28} Functional
independence status was examined by occupational therapists using the
Katz Activities of Daily Living (ADL) \textsuperscript{29} and Lawton
and Brody Instrumental Activities of Daily Living
(IADL)\textsuperscript{30} on admission and at discharge from geriatric
rehabilitation. Scores of ADLs and IADL ranged between 0--6 and 0--8
points, respectively, with higher scores indicating higher level of
independence. ADL and IADL scores at three months post-discharge were
assessed by trained researchers via telephone interview with the patient
and/or carer. All types of medications (chronic, acute, over the
counter) that patients were taking across the care transitions (acute
admission, admission to and discharge from geriatric rehabilitation
wards) were extracted from medical records.

\emph{Potentially inappropriate medications}\textbf{:} PIMs and PPOs
were quantified according to version 2 of the Screening Tool of Older
People's Prescription (STOPP) and the Screening Tool to Alert Doctors to
the Right Treatment (START) criteria,
respectively.\textsuperscript{6}These explicit screening tools,
developed using expert opinion using available evidence from literature
and clinical guidelines, consisted of 80 STOPP and 34 START items to
identify unnecessary medications and omitted medications, respectively.
PIMs/PPOs were identified across the three care transitions (acute
admission, on admission to and at discharge from geriatric
rehabilitation ward) during geriatric rehabilitation care. The data were
extracted by a qualified pharmacist, with regular independent checks by
another qualified pharmacist.

\emph{Outcome variables}\textbf{:} The primary outcomes of interest were
hospital readmissions, and mortality after hospital discharge.
Readmission was defined as an unplanned acute readmission after
discharge and was obtained from medical records and at 3-month phone
interviews. Mortality was defined as death of patient at 3- or 12-months
post-discharge and was obtained from the Registry of Births, Deaths and
Marriages Victoria and medical records. The secondary outcome was
functional status at 3-months post discharge from geriatric
rehabilitation.

\emph{Data analysis}\textbf{:} Descriptive statistics was undertaken to
summarize the main characteristics of older patients. Continuous
variables were reported as mean with corresponding standard deviation,
or median with interquartile ranges if not normally distributed.
Categorical variables were reported as absolute frequencies and
percentages. The prevalence of PIPs (PIM/PPO) was calculated as a ratio
between the number of patients exposed to at least 1 PIP (PIM/PPO) and
the total number of patients included. To investigate the associations
between PIPs identified at discharge and subsequent outcomes (e.g.,
hospital readmission, mortality, functional outcomes), PIPs were
measured as a dichotomous variable (yes/no), as well as a continuous
variable (number of PIPs). Only patients discharged alive were
considered in the estimations related to analyses involving associations
between PIPs and post-discharge health outcomes. For comparison between
PIP and outcome variables, Chi-square test were employed for
categorical/dichotomous variables, and the independent t-test was used
for continuous variables. The McNemar and Cochran's Q tests were used to
compare the prevalence of PIM/PPO between two and three care
transitions, respectively. Multivariate logistic regression analyses
were employed to identify the independent associations between discharge
PIMs/PPOs, and number of discharge medications with primary health
outcomes. Multivariate regression analyses were further applied on PIM
categories, and it was undertaken by merging similar PIMs together
(e.g., Groups B and C, Groups D and K), Group A (indication) and fewer
PIMs (E-J, L, M). Similarly, PPOs were categorised as Group A
(cardiovascular medications), Group I (Vaccines) and other groups (B-D,
F-H) and their associations were assessed against the primary outcomes.
Linear regression analyses were used to determine the associations
between discharge PIMs/PPOs and secondary outcomes (i.e., ADL and IADL).
All multivariate analyses were adjusted for age, Charlson comorbidity
index (CCI), cognitive impairment, length of stay during geriatric
rehabilitation and number of discharge medications.

\textbf{Results}

\textbf{Patient characteristics}

Table 1 shows the patients' characteristics on admission to geriatric
rehabilitation and outcomes during hospital stay and following discharge
from geriatric rehabilitation. The mean age was 82.6 years and 56.3\%
were female. Approximately, 72\% of patients used a walking aid and the
median frailty and Charlson comorbidity scores were 6 {[}5 -- 7{]}and 2
{[}1 -- 4{]}, respectively. The primary reasons for hospital admissions
were musculoskeletal disorders (47\%), followed by neurological
disorders (15\%). More than 60\% of the patients had cognitive
impairment and the median CIRS score was 12 {[}9 -- 16{]}. Mortality
rate at 3 months was 7.1\% and 19.4\% died at 12 months. The 30- and
90-day all-cause readmissions rates were 14.8\% and 23.7\%,
respectively.

\textbf{PIMs and PPO prevalence}

At discharge from a geriatric rehabilitation ward, a total of 18,704
medications were prescribed. The most frequently prescribed medications
were analgesics (80.9\%), cardiovascular medications (72.2\%), vitamin D
(61.1\%) and psychotropics (50.8\%) (\emph{Appendix I} ).

A total of 1856 PIMs and 1368 PPOs (4482 PPOs including vaccines) were
identified (A\emph{ppendix II} ). The percentage of patients with at
least one PIM was 61.6\% on acute admission, 58.8\% on admission to
geriatric rehabilitation and 54.8\% at discharge from geriatric
rehabilitation. The percentage of patients with at least one PPO was
91.8\% on acute admission, 91.6\% on admission to geriatric
rehabilitation and 90.8\% at discharge from geriatric rehabilitation.
However, on excluding vaccine data, patients with at least 1 PPO reduced
to 51.9\%, 51.4\% and 46.3\%, respectively. There was a significant
change in the prevalence of any PIM use across the care transitions
(acute admission, admission to and discharge from geriatric
rehabilitation), as was with the use of PPOs but without vaccine data.
However, the reduction rate was consistent when the use of any PIMs or
PPOs were compared between acute admission and geriatric rehabilitation
discharge (\emph{Appendix III} ).

Association of inappropriate prescribing with outcome variables

Table 2 reports the associations between the occurrence of at least one
PIM or PPO or PIP identified at geriatric rehabilitation discharge with
patient and disease characteristics, and outcomes. Patients with at
least one PIM or PIP were significantly more likely to be discharged on
higher number of medications, or to have greater than 10 discharge
medications (hyper polypharmacy) and were mainly admitted due to
cardiovascular diseases. Patients with at least 1 PIM, PPO or PIP were
more common in patients with opioid, anti-inflammatory, Immunomodulatory
and analgesic prescriptions, and with a greater burden of
co-morbidities. Patients with at least 1 PPO were most likely admitted
due to musculoskeletal disorders and were using walking aids. PIMs were
less prevalent in older age, in patients with cognitive impairment and
with longer hospitalisation.

Table 3 provides adjusted and crude ORs of the associations between
inappropriate prescribing identified at geriatric rehabilitation
discharge and outcome variables. On a univariate analysis, patients with
at least 1 PIM and PIP were associated with an increased odds of
hospital readmissions at longer follow up (i.e., 3 month), but not at 30
days of follow-up. A similar association was also evident for these
outcomes when considering the numbers of PIMs and PIPs as a continuous
variable. In addition, PIPs and PPOs as continuous variables also
demonstrated a significant association with mortality data collected at
3 month and 12 months of follow-up.

After adjustment for confounding variables, exposure to at least 1 PIM,
PPO and PIP did not show a significant association with post-discharge
health outcomes. However, the number of discharge medications were
significantly associated with hospital readmission at 30-days and
90-days follow-up. The prescription of each additional medication at
discharge from geriatric rehabilitation increased the odds of hospital
readmission by 1.04 (AOR 1.04; 95\% CI 1.01-1.07) and 1.06 (AOR 1.06;
95\% CI 1.03 -1.09) at 30-days and 90-days post-discharge, respectively.
Specifically, patients discharged with at least 1 cardiovascular
medication showed a significant increased odds of hospital readmissions
at 30-days (AOR 1.43; 95\% CI 1.03-1.98) and 90-days of follow-up (AOR
1.45; 95\% CI 1.10-1.89). Conversely, patients whose cardiovascular PPOs
were omitted at discharge from geriatric rehabilitation were associated
with 12-month mortality (AOR 1.34; 95\% CI 1.00-1.78) although this was
not evident for mortality and other outcomes collected at shorter
follow-up (Table 4). PPOs related to CVD medications were mainly due to
failure to prescribe or continue use of beta-blockers in patients with
ischaemic heart disease, angiotensin converting enzyme inhibitors
(ACEIs) in patients with systolic heart failure and/or documented
coronary artery disease and statin therapy in patients with a documented
history of coronary, cerebral or peripheral vascular disease with
substantial life expectancy. On the other hand, PIMs related to
CNS/psychotropics and fall risk increasing medications were
significantly associated with the 30-day hospital readmission (AOR 1.53;
95\% CI 1.09 - 2.15).

Linear regression analyses of the association between discharge PIMs or
PPOs and the longitudinal changes of ADLs/IADs from geriatric
rehabilitation discharge to 90-days post-discharge are shown in Table 5.
There was no significant association between PIMs and gains in
ADLs/IADLs scores but PPO use, and specifically PPOs inclusive of
vaccines negatively affected ADL/IADL gains (PPO [?] 1: \selectlanguage{greek}β \selectlanguage{english}= -0.232, 95\%
-0.445 to -0.019; Number of PIPs (including vaccines): \selectlanguage{greek}β \selectlanguage{english}= -0.107, 95\%
CI -0.194 to -0.021).

\textbf{Discussion}

This is the first study to investigate the impact of PIMs and PPOs at
discharge from geriatric rehabilitation on unplanned readmissions and
mortality among geriatric rehabilitation inpatients in Australia. While
the prevalence of PIM and PPO use at different time points during the
transition into geriatric rehabilitation care was high, the proportion
of patients taking any PIMs/PPOs significantly reduced from acute
admission to geriatric rehabilitation discharge. The use of at least 1
PIMs, PPOs or PIPs at geriatric rehabilitation discharge were not
associated with an increased risk of unplanned readmission and
mortality, be it in the short or long-term. Specific groups of PIMs
(CNS/psychotropics and fall risk increasing medications) were
significantly associated with the 30-day hospital readmission and
cardiovascular PPOs with the 12-month mortality. Furthermore, an
increased number of discharge medications was significantly associated
with 30-day and 90-day hospital readmissions. The use and number of PPOs
that also included vaccine omissions were negatively associated with
gains in IADL scores at 90-days following discharge from geriatric
rehabilitation.

Temporal changes in the prevalence of PIMs and PPOs from acute admission
to geriatric rehabilitation discharge were investigated in this study.
It showed a significant reduction in PIMs and PPOs as patients moved
from acute admission to discharge. While these findings were consistent
with other studies,\textsuperscript{31,32} there were also studies that
did not show a significant difference\textsuperscript{10,33} or have
shown a rather increased PIM prevalence during the transition from
admission to discharge.\textsuperscript{13} The current study has shown
that the longer that patients stayed in geriatric rehabilitation ward,
the fewer patients were likely to be exposed to PIMs. Therefore, it was
not surprising to see a decline in the prevalence of PIM use from acute
admission to discharge in this study.

In the present study, neither PIMs, PPOs nor PIPs were shown to have an
association with readmission and mortality, but a higher number of
discharge medications was a major predictor for unplanned hospital
readmission at 30-days following discharge from geriatric
rehabilitation. This finding is not consistent with previous reports
conducted in acute care,\textsuperscript{7,34} in relation to hospital
readmission and mortality. A recent meta-analysis highlighted the burden
of medication-related harm due to potentially inappropriate
prescribing.\textsuperscript{7} For example, patients using at least 1
PIM use in the inpatient setting (compared with non-users) were
associated with a 91\% increased odds of medication-related hospital
admission (AOR 1.91, 95\% CI 1.21-3.01), and 60\% increased odds of
dependency in at least 1 ADL (AOR 1.60; 95\% CI 1.28--2.01). Informed by
this review, a prospective telephone follow-up study with clinical audit
of electronic medical record in general medical wards was also
subsequently conducted to assess the links between inappropriate
medication and clinical and functional outcomes (e.g., unplanned
hospital readmission, dependency in activities of daily
living).\textsuperscript{34} It was found that exposure to at least 1
PIM use was associated with an increased occurrence of unplanned
hospital readmission (AOR 5.09; 95\% CI 2.38-10.85), and there was also
an increased in the likelihood of patients experiencing dependency in at
least 1 ADL after hospital discharge (AOR 2.31; 95\% CI
1.08-4.20).\textsuperscript{34} The reason for this difference may be
that related to the healthcare setting itself, in that patients admitted
to geriatric rehabilitation wards stayed longer (median 19.8 days vs 5
days)\textsuperscript{34} and were likely exposed to fewer PIMs than
patients discharged from general medical wards. In addition, the
previous study\textsuperscript{34} was conducted during the intense lock
down due to COVID-19 and this may have impacted healthcare provision
because of understaffing. The morbidity and mortality pattern were also
different -- for example, 90-days readmission was 36\% in a previous
study\textsuperscript{34} but 21.7\% in the current study, it may be due
to COVID-related restrictions with limited eligibility for hospital
care. The lack of association between hyper polypharmacy (defined as
prescription of 10 or more medications) and clinical outcomes in a
previous study\textsuperscript{34} may be because only regular
medications were counted unlike the current study. Medications
prescribed \emph{pro re nata} , including benzodiazepines for sleep aid
may have been missed in the calculation, which was the main limitation
for the previous study.\textsuperscript{34} It should be noted that the
prescription of psychotropic and fall risk increasing PIMs were
associated with 30-day readmission in the present study.

The present results are consistent with previous
studies,\textsuperscript{35,36} showing that as the number of
medications increase, so does the prevalence of 30-day and 90-day
hospital readmissions. Basnet et al.\textsuperscript{35} found that the
number of discharge medications was significantly associated with
increased hospital readmission within 30-days, with the risk of
rehospitalization increasing by 4\% for every added medication (OR 1.04;
95\% CI 1.03-1.05). Another study\textsuperscript{36} of 647 patients
discharged from geriatric medicine acute care wards showed that taking
eight or more medications was significantly associated with 90-day
hospital readmission.

\textbf{Implications for practice and future research}

It was encouraging to see a reduction in the prevalence of PIMs and PPOs
while geriatric rehabilitation inpatients moved from acute admission to
discharge but still a large proportion of patients received PIMs and
PPOs at discharge from a geriatric rehabilitation. At discharge,
patients may not only continue to use PIMs/PPOs from acute admission,
but it may also be a site where new inappropriate medications may be
introduced.\textsuperscript{37} These newly added inappropriate
medications conferred a higher risk of adverse events compared to
chronic inappropriate medications.\textsuperscript{37} Therefore,
designing strategies to reduce the prescription of medications with high
risk profile and tailoring deprescription practice would be an important
intervention worth considering. The group of PIM medications that may be
benefited from the deprescription intervention included psychotropics,
fall-risk increasing drugs and other CNS acting agents. Equally
important, medications that are beneficial for older people needs to be
started or let them to continue at discharge and beyond. However, there
should be a balance which medications to prescribe or to deprescribe --
for example, in the current study, prescriptions related to CVD
medications overall were associated with short-term hospital
readmissions, similarly their omission has significantly increased
mortality in the long-term. The better approach to optimise CVD
medication use in geriatric rehabilitation inpatients is to reduce CVD
PIMs (e.g., use of centrally active antihypertensives and use of
amiodarone as first-line antiarrhythmic therapy in supraventricular
tachyarrhythmias) and continue to prescribe beneficial CVD medications
(e.g., use of beta-blockers in patients with ischaemic heart disease,
and ACEIs in patients with systolic heart failure and/or documented
coronary artery disease) unless contraindications existed. In fact, (de)
prescription practice is determined by several internal and external
factors, including prescriber's reluctance to stop medications
prescribed by other healthcare providers and a lack of time for
comprehensive evaluation of patients.\textsuperscript{38} Active
involvement of patients and their families in the prescribing
decision-making process is an important strategy to empower patients in
their self-care,\textsuperscript{39} including designing ways to adopt
non-pharmacological approaches or substitute with safer alternatives.

While the occurrence of PIMs offers an opportunity to improve care
through deprescription, more studies are needed to assess the
feasibility of conducting deprescription intervention to reduce PIMs
among geriatric rehabilitation inpatients. Moreover, future studies are
required to examine the association between the presence of PIMs and
PPOs with medication-related hospital admissions, rather than all-cause
readmission.

\textbf{Strengths and limitations of the study}

This is the largest longitudinal study to report on the association
between potentially inappropriate prescribing and post-discharge health
outcomes in a cohort of geriatric rehabilitation inpatients using
STOPP/START v2 criteria. The data were collected through a highly
standardized comprehensive assessments performed by a trained
multidisciplinary team, providing detailed information, which may
strengthen the clinical robustness of our findings. However, it was a
single-site study in a geriatric rehabilitation inpatient- the
interpretation and generalisability of the findings to other care
settings or patients must be done with caution. The observational study
design limits the ability to establish a causal relationship between
inappropriate medication and clinical outcomes. In addition, whether
patients discharged from geriatric rehabilitation were adhered to their
medication or have made changes to their prescription following
discharge from geriatric rehabilitation were unable to verify.

\textbf{Conclusions}

The proportions of patients taking any PIMs and/or PPOs were
significantly reduced from acute admission to geriatric rehabilitation
discharge. Neither PIM, nor PPO use at geriatric rehabilitation
discharge were consistently associated with an increased risk of
unplanned readmission and mortality. However, the number of discharge
medications were strongly associated with short and long-term
readmission. The use and number of PPOs that included vaccine omissions
were negatively associated with the longitudinal gains in IADL scores at
90-days following geriatric rehabilitation discharge. Interventions
toward patient-tailored appropriate (de) prescribing in geriatric
rehabilitation patients are needed, taking the number of medications,
unnecessary and omitted medications into account.

\textbf{Acknowledgements}

ABM gratefully acknowledges the support provided by Deakin University
through the Alfred Deakin Postdoctoral Research Fellowship. The authors
acknowledge all members of the multidisciplinary team at the Royal
Melbourne Hospital, Royal Park Campus, for their clinical assessments of
the RESORT cohort, the @AgeMelbourne team for their role in the data
collection and Professor Liliana Orellana for her statistical support in
the data analysis.

\textbf{Author contributions}

All authors made substantial contribution to the design and conception
of the study. Data collection was performed by CHS and EMR. ABM (first
author) and EM involved in data analysis and interpretation of data. The
first draft of the manuscript was written by ABM (first author) and all
authors reviewed and revised the manuscript. All authors have read and
approved the final manuscript.

\textbf{Compliance with ethical standards}

\textbf{Funding:} This study was funded by the Medical Research Future
Fund provided by the Melbourne Academic Centre for Health.

\textbf{Conflict of interest} : The authors declare that they have no
competing interests.

\textbf{Ethical approval:} The study was approved by the Melbourne
Health Human Research Ethics Committee (HREC/17/MH/103) and performed in
accordance with the principles of the Declaration of Helsinki.

\textbf{Informed consent:} All participants (or their nominated proxy)
provided their written informed consent to participate in this study.

\textbf{Data availability} : The RESORT data that support the findings
of this study are available from ABM (fifth author) upon reasonable
request.

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