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: β = -0.232, 95%
-0.445 to -0.019; Number of PIPs (including vaccines): β = -0.107, 95%
CI -0.194 to -0.021).