Dysvascular amputation and comorbidity
Table IV. Hierarchical multiple regression (final model) predicting motor Functional Independence Measure (FIM) gain
Unstandardized coefficients
Constant
Days since amputation
Age
Admission Motor FIM
Days on inpatient rehabilitation
White blood cells
Intravenous antibiotics
Creatinine
On haemodialysis at admission
Wound vac at admission
Diabetes
Haemoglobin
Previous amputation
95% confidence interval
B Std. error t Sig. Lower bound Upper bound
19.25
0.08
–0.01
–0.05
0.06
0.23
–4.07
–1.85
0.90
7.04
–1.71
–0.76
5.53 11.38
0.10
0.08
0.12
0.17
0.37
2.55
1.05
4.88
3.62
2.21
0.79
2.94 1.69
0.79
–0.09
–0.43
0.34
0.64
–1.59
–1.76
0.19
1.94
–0.77
–0.96
1.89 0.09
0.43
0.93
0.67
0.73
0.53
0.11
0.08
0.85
0.06
0.44
0.34
0.06 –3.35
–0.12
–0.17
–0.29
–0.28
–0.50
–9.14
–3.94
–8.78
–0.15
–6.10
–2.32
–0.29 41.85
0.29
0.15
0.18
0.40
0.96
1.00
0.24
10.58
14.23
2.68
0.81
11.36
FIM: Functional Independence Measure; SE: standard error.
explained, F (11, 85) = 0.60, p = 0.82. Using the same
model variables and steps (with the addition of days on
inpatient rehabilitation in Step 1), results were similar
for motor FIM gain with no predictor variable having
a significant association with the outcome. In the final
model, shown in Table IV, 14.3% of the variance was
explained, F (11, 96)v1.08, p = 0.38.
Functional gains during inpatient rehabilitation
373
At the time of discharge, 24 (21.2%) patients exceeded
the MDC90 value of 17.84 for FIM motor gain. The
MDC90 value indicates that there is a 90% confidence
that change in motor FIM greater than 17.84 is not due to
measurement error. The effect size was large (1.03), as
was the SRM value (1.39), using Cohen’s criteria (19).
DISCUSSION
This is the first study to evaluate factors potentially
associated with interruptions to rehabilitation. In this
study, 16.2% of dysvascular patients participating
in inpatient rehabilitation due to a lower extremity
amputation required an unplanned transfer from the
rehabilitation unit. This is consistent with the rate of
unplanned transfers found in previous studies of ampu-
tee patients, which ranged from 6.6% to 22.8% (6, 20).
Model testing indicated that renal function, use of IV
antibiotics on admission, history of diabetes, history of
previous contralateral amputation, presence of a wound
vac, and age were not associated with an increased risk
of an unplanned transfer from inpatient rehabilitation.
Together, these factors explained a relatively modest
amount of the variance, suggesting that other factors
may better predict unplanned transfers. The only factor
significantly associated with unplanned transfers was
gender, with an increased incidence of unplanned
transfers in women compared with men, which is also
consistent with the findings of a previous study by
Meikle et al. (6) Other factors, such as a shorter span
of time between amputation and inpatient rehabilitation
admission, and other markers of peripheral vascular
disease were also not statistically significantly as-
sociated with the incidence of unplanned transfers in
our study. Although older age also did not appear to
increase the risk of transfer in our study, other studies
have found evidence that older patients have a higher
rate of transfer from acute rehabilitation to acute care
across all rehabilitation diagnoses (12).
The analysis of our results also found that none of
the factors examined were significantly associated with
functional outcomes in terms of FIM efficiency in this
limited sample. No definitive conclusions can be drawn
from these results due to the limited scope and sample
size of this study; however, our findings would be
consistent with the idea that comorbidities associated
with dysvascular amputations do not increase the risk
of unplanned transfers from inpatient rehabilitation,
nor do they limit functional gains during rehabilita-
tion. This may be influenced by the increased level of
medical supervision during inpatient rehabilitation,
which allows for the prevention of many major medical
complications, and is consistent with previous research
showing the overall benefits of inpatient rehabilitation
over subacute rehabilitation in this population (17,
21). Finally, only approximately one-fifth of patients
exceeded a FIM motor gain of 17.84, or the threshold
of change not due to measurement error. This suggested
modest actual gains in motor function for the sample.
This study has several limitations that should be
considered when interpreting the results. First, the
sample was drawn from a single inpatient rehabilita-
tion facility in a single health system and therefore
the generalizability of these results is limited. Studies
of amputee patients in different health systems and
across different demographics are needed to show
whether these outcomes are consistent for the amputee
population at large, though the non-novel aspects of
J Rehabil Med 51, 2019