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.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)23 and the Cumulative Illness
Rating Scale (CIRS).24 CCI and CIRS scores ranged from
0-37 and 0-56, respectively. Frailty was assessed by physicians using
the Clinical Frailty Scale (CFS),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 <
24 points,26 Montreal Cognitive Assessment score
< 26 points,27 or the Rowland Universal
Dementia Scale < 23 points.28 Functional
independence status was examined by occupational therapists using the
Katz Activities of Daily Living (ADL) 29 and Lawton
and Brody Instrumental Activities of Daily Living
(IADL)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.
Potentially inappropriate medications: 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.6These 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.
Outcome variables: 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.
Data analysis: 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.