Predictors of Functional Decline in Activities of Daily Living at Discharge in Patients After Cardiovascular Surgery

Abstract

Background: This study aimed to investigate the trajectory of functional recovery of activities of daily living (ADL) from the time of admission up to hospital discharge, and explored which preoperative and postoperative variables were independently associated with functional decline in ADL at discharge of patients after cardiovascular surgery.

Methods and Results: In this observational study, we evaluated ADL preoperatively and at discharge using the Functional Independence Measure (FIM) in patients after cardiovascular surgery. Functional decline in ADL was defined as scoring 1–5 on any one of the FIM items at discharge. Multiple logistic regression was performed to predict the functional decline in ADL at discharge. We found that 18.8% of elective cardiovascular surgery patients suffered from decreased ADL at discharge. The Mini-Mental State Examination (odds ratio (OR): 0.573, 95% confidence interval (CI): 0.420–0.783), gait speed (OR: 0.032, 95% CI: 0.003–0.304) and initiation of walking around the bed (OR: 1.277, 95% CI: 1.103–1.480) were independently associated with decreased ADL at discharge.

Conclusions: A functional decline in ADL at discharge can be predicted using preoperative measures of cognitive function, preoperative gait speed and postoperative day of initiation of walking. These results show that preoperative cognitive screening and gait speed assessments can be used to identify patients who might require careful postoperative planning, and for whom early postoperative rehabilitation is needed to prevent serious functional ADL deficits.

The goal of acute-phase care after cardiovascular surgery is to address mobilization, ambulation and activities of daily living (ADL) without delay.¹ Cardiovascular surgery is now increasingly routinely performed in elderly patients, so many high-risk older patients with severely deteriorated functional status and multiple comorbidities are increasingly being referred for cardiac surgery, which results in increased numbers of patients requiring a longer hospital stay at the end of the postoperative acute phase before they can safely return home. Accordingly, the number of patients needing longer rehabilitation programs in the inpatient setting continues to rise.^2,3

Patients admitted to hospital for acute problems have an increased risk of a functional decline in ADL following discharge,^4–6 which is associated with increasing dependency, prolonged length of hospital stay and higher mortality risk.⁷ Furthermore, the ability to perform ADL is a strong independent predictor of outcomes for cardiac rehabilitation patients following discharge, including those who undergo cardiovascular surgery.^8,9 Previous studies have shown that 24–30% of patients report ADL impairment at hospital discharge after operations other than cardiac surgery.^10,11 Several studies have focused on the long-term functional recovery of ADL after cardiovascular surgery.^12–14 Although ADL are a strong independent predictor of outcome following discharge, to the best of our knowledge no previous studies have investigated predictors of functional decline in ADL at the time of hospital discharge following cardiovascular surgery.

Several studies have shown that preoperative physical and cognitive functions have strong predictive value for postoperative outcomes.^3,12,15,16 However, the associations between preoperative physical and cognitive functions and ADL at hospital discharge are not clear. In addition, preoperative evaluation of physical and cognitive functions is not currently standardized. Postoperative complications, such as delirium and prolonged immobility, have been also proposed as risk factors after cardiac surgery.^17,18 It remains unclear whether there is an association between the postoperative course, including rehabilitation programs, and functional decline in ADL at the time of hospital discharge. To this end, we aimed to explore which preoperative and postoperative variables were independently associated with functional decline in ADL at discharge of patients after cardiovascular surgery.

Methods

Study Design

In this prospective observational study, ADL assessment was performed preoperatively and at discharge whereas evaluation of cognitive and physical functions was performed only preoperatively. Preoperative and postoperative data from patients’ records were collated. Multivariate analysis was used to predict functional decline in ADL at discharge and performed using variables with a P value <0.05 by univariate analysis. Thus, receiver operating characteristic (ROC) curve analysis was performed to determine the area under the curve (AUC) and cutoff values of variables extracted by the multivariate analysis.

For postoperative cardiac rehabilitation, the functional recovery program and criteria for the intensity of exercise were based on the guidelines of the Japanese Circulation Society (JCS).¹ Patients participated in postoperative cardiac rehabilitation consisting of active or passive extremity exercise in bed, sitting on the edge of the bed, standing at the bedside and walking around the bed on the ward. Patients continued walking for up to 300 m and performed endurance training using a stationary bike or treadmill in the rehabilitation center until they were discharged from hospital. Progress in postoperative cardiac rehabilitation was evaluated according to criteria for evaluating the results of exercise stress tests.¹

Subjects

Patients undergoing elective cardiovascular surgery, coronary artery bypass grafting, valve replacement and/or arterial vascular surgery were eligible for this study. Exclusion criteria were preoperative impairment of ADL expected for bathing and stair climbing; preoperative Mini-Mental State Examination (MMSE) score <23 points; and severe postoperative complications or death in hospital. Patients were recruited from Hyogo College of Medicine College Hospital between April 2017 and March 2019. This study was approved by the Research Ethics Committee of Hyogo College of Medicine under protocol number 201704-063 and was conducted according to the Declaration of Helsinki.

ADL Assessment

ADL performance was assessed preoperatively and at discharge using the FIM^19,20 by a physiotherapist. The FIM assesses the degree of independence or assistance required by a person to perform a range of motor and cognitive tasks of daily living. The FIM comprises 18 items, including 13 motor items as follows: eating, grooming, bathing, dressing the upper body, dressing the lower body, toileting, bowel management, bladder management, transfer to bed/chair/wheelchair, transfer to toilet, transfer to tub/shower, walking or wheelchair propulsion, and climbing stairs. The remaining 5 items assess cognitive state: comprehension, expression, social interaction, problem solving, and memory. Each of the 18 items is scored as 1 for completely dependent on assistance; 2, a high degree of assistance required; 3, moderate assistance required; 4, minimal assistance; 5, only supervision required; 6, high level of independence and 7, complete independence.

Preoperative Cognitive Function Assessment

The Japanese version of the MMSE was used to assess preoperative cognitive function.²¹ The MMSE scale ranges from 0 to 30 points, where higher scores indicate better cognitive function. MMSE scores <23 are classified as cognitive impairment.²²

Preoperative Physical Functional Assessment

A physiotherapist preoperatively assessed handgrip strength, knee extension strength and gait speed. Handgrip strength was measured using a digital handgrip meter. Knee extension strength was assessed using a hand-held dynamometer for isometric quadriceps contraction at 90° of knee flexion when seated and was divided by the weight. The highest value of 2 attempts of either handgrip strength or knee extension strength was noted. Gait speed was assessed as walking speed over 10 m.

Frailty Assessment

We evaluated frailty using the Japanese version of the Cardiovascular Health Study (J-CHS) frailty index,²³ which assesses 5 domains of frailty, namely, weight loss, weakness, exhaustion, slowness and low physical activity. Frailty is defined as having 3–5 of the following components: (1) weight loss of 2–3 kg in the past 6 months; (2) weakness: handgrip strength <26 kg for men or <18 kg for women; (3) exhaustion: answering yes to the question “Have you felt tired without a reason in the last 2 weeks?”; (4) slowness: gait speed <1.0 m/s; (5) low physical activity: answering no to both of the questions “Do you engage in moderate levels of physical exercise or sports aimed at health?” and “Do you engage in low levels of physical exercise aimed at health?”

Preoperative Data Collection

Subjects’ preoperative characteristics were extracted from the medical records. We noted age, sex, body mass index (BMI), left ventricular ejection fraction (LVEF), percent vital capacity (%VC), forced expiratory volume 1.0 s percent (FEV1%), and the comorbidities frailty, hypertension (HT), diabetes mellitus (DM), chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), old myocardial infarction (OMI), peripheral vascular disease (PVD), orthopedic disease (OD), and cerebrovascular disease (CVD).

Postoperative Data Collection

We recorded the type and duration of surgery, volume of blood loss, total fluid balance, postoperative days on ventilation, length of ICU stay, the day of initiation of postoperative mobilization exercises, including standing at the bedside and walking around the bed, and finally, the incidence of postoperative complications of heart failure, re-operation for major bleeding, new onset of arrhythmia, renal failure and delirium.²⁴

We also recorded the length of hospital stay after cardiovascular surgery.

Statistical Analysis

Subjects were divided into 2 categories according to ADL at discharge, designated as “independent ADL” scoring 6 or 7 on all of the FIM items or “decreased ADL” scoring 1–5 on at least 1 of the FIM items.

Results of parametric data are presented as mean and standard deviation. Median and interquartile range (IQR) were used for nonparametric data. Proportion was used for categorical variables.

In the univariate analysis, Student’s t-test was used to compare age, BMI, LVEF, %VC, FEV1%, handgrip strength, knee extension strength, gait speed, duration of surgery, blood loss volume and total fluid balance. The Mann-Whitney U test was used to compare the preoperative FIM score with the score at discharge, MMSE, postoperative ventilation days, length of ICU stay, the day of initiation of postoperative standing at the bedside and walking around the bed, and length of hospital stay. The Chi-square test was used to compare sex, frailty, comorbidities, type of surgery, and postoperative complications.

The magnitude of index responsiveness was evaluated according to standardized effect size. Cohen’s d was defined whereby 0.2, 0.5 and 0.8 indicated small, moderate and large degrees of responsiveness, respectively.^25,26 Phi coefficient and Pearson’s correlation coefficient were defined whereby 0.2, 0.3 and 0.5 indicated small, moderate and large degrees of responsiveness, respectively.^25,26

In the multivariate analysis, multiple logistic regression was used to predict functional decline in ADL at discharge (coded as 0=independent ADL, 1=decreased ADL). Those variables with a P value <0.05 by univariate analysis were included and the variables considered to be multicollinear were excluded in the multiple logistic regression.

ROC curve analysis was performed to determine the AUC of variables extracted by multiple logistic regression. Youden-index quantification was used to identify the optimal cutoff values for predicting decreased ADL at discharge. A P value <0.05 was considered statistically significant throughout.

All statistical analyses were performed using Statistical Package for Social Sciences (SPSS) version 21.0.

Results

As shown in Figure 1, 220 patients undergoing cardiovascular surgery were selected for the study, but 54 had to be excluded because of missing data (n=22), not having preoperative independent ADL (n=16), having preoperative cognitive impairment (n=9), severe postoperative complications (n=5) and death in hospital (n=2). Of the remaining 166 patients, 136 (81.9%) were classified as independent ADL and 30 (18.1%) as decreased ADL at discharge.

Figure 1.

Flow chart of study enrollment. ADL, activities of daily living.

The length of hospital stay was significantly longer for the group with decreased ADL (P<0.001) than for the independent ADL group (18.0, IQR; 14.0–24.0 vs. 29.5, IQR; 20.25–36.75, P<0.001).

The FIM scores preoperatively and at discharge were significantly lower for the decreased ADL group than for the independent ADL group (126, IQR; 123.5–126 vs. 123, IQR; 119–125.75, P=0.001 and 126, IQR; 125–126 vs. 113, IQR; 111–116, P<0.001). The proportions of patients with functional decline at discharge for each of the FIM items are shown in Table 1.

Table 1. Proportion of Patients With Decline in Each FIM Item

Item	No. showing decline
Eating	1 (3%)
Grooming	6 (20%)
Bathing	10 (3%)
Upper body dressing	3 (10%)
Lower body dressing	3 (10%)
Toileting	3 (10%)
Bladder management	1 (3%)
Bowel management	1 (3%)
Bed to chair transfer	4 (13%)
Toilet transfer	4 (13%)
Tub/shower transfer	23 (76%)
Walking	5 (16%)
Stairs	16 (53%)
Comprehension	1 (3%)
Expression	1 (3%)
Social interaction	1 (3%)
Problem solving	2 (6%)
Memory	2 (6%)

FIM, Functional Independence Measure.

The patients’ preoperative characteristics are shown in Table 2. Patients in the decreased ADL group were significantly older than in the independent ADL group (P=0.001, d=0.68). The percentage of women (P=0.029, φ=0.16), frail persons (P=0.002, φ=0.24) and those with comorbidities, including CKD (P=0.015, φ=0.18) and OD (P=0.036, φ=0.16), were significantly higher in the group with decreased ADL. Preoperative MMSE (P<0.001, d=1.08) and physical function, including handgrip strength (P=0.001, d=0.66), knee extension strength (P=0.021, d=0.54) and gait speed (P<0.001, d=1.08), were all significantly lower in the decreased ADL group.

Table 2. Preoperative Characteristics of the Study Patients

	Independent ADL (n=136)	Decreased ADL (n=30)	P value	Effect size
Age	67.8±9.2	73.7±6.2	0.001	d=0.68
Sex (female, %)	36 (27%)	14 (47%)	0.029	φ=0.16
BMI (kg/m2)	23.3±3.3	23.9±4.4	0.441	d=0.17
Frailty	27 (20%)	14 (47%)	0.002	φ=0.24
MMSE (points)	29.0±1.4	27.4±1.8	<0.001	d=1.08
LVEF (%)	61.0±12.9	59.1±14.2	0.457	d=0.14
%VC (%)	99.0±18.7	91.8±15.1	0.051	d=0.40
FEV1% (%)	77.6±11.6	77.2±18.0	0.86	d=0.03
HT	62 (47%)	14 (47%)	0.915	φ=0.01
DM	50 (38%)	11 (37%)	0.992	φ=0.01
CKD	23 (17%)	11 (37%)	0.015	φ=0.18
COPD	9 (6%)	2 (7%)	0.992	φ=0.01
OMI	21 (16%)	5 (17%)	0.867	φ=0.01
PVD	6 (4%)	1 (3%)	0.79	φ=0.02
OD	16 (12%)	8 (27%)	0.036	φ=0.16
CVD	10 (7%)	5 (17%)	0.107	φ=0.12
Handgrip strength (kg)	27.9±7.9	22.8±7.1	0.001	d=0.66
Knee extension strength (kgf/kg)	0.45±0.11	0.39±0.12	0.021	d=0.54
Gait speed (m/s)	1.20±0.20	0.95±0.34	<0.001	d=1.08

ADL, activities of daily living; BMI, body mass index; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVD, cerebrovascular disease; DM, diabetes mellitus; FEV1%, forced expiratory volume 1.0 s percent; HT, hypertension; LVEF, left ventricular election fraction; MMSE, Mini-Mental State Examination; OD, orthopedic disease; OMI, old myocardial infarction; PVD, peripheral vascular disease; %VC, percent vital capacity.

The postoperative data are shown in Table 3. The 2 ADL groups differed significantly in the type of surgery, including combined valve replacement and aorta replacement, which was more frequent in the decreased ADL group than in the independent ADL group. There were no significant differences in duration of surgery, blood loss volume and total fluid balance. However, length of time on ventilation (P=0.001, r=0.25) and ICU stay (P=0.001, r=0.27) were significantly longer, and initiation of postoperative standing at the bedside (P<0.001, r=0.31) and walking around the bed (P<0.001, r=0.34) were significantly delayed in the decreased ADL group relative to the independent ADL group. The occurrence of renal failure (P=0.014, φ=0.19) and postoperative delirium (POD) (P=0.003, φ=0.23) were also increased significantly in the decreased ADL group.

Table 3. Postoperative Data of the Study Patients

	Independent ADL (n=136)	Decreased ADL (n=30)	P value	Effect size
Type of surgery
CABG	35 (26%)	5 (17%)	0.293	φ=0.08
Valve replacement	37 (28%)	12 (40%)	0.164	φ=0.10
Aorta replacement	37 (28%)	7 (23%)	0.664	φ=0.03
Combined CABG and valve replacement	12 (9%)	0 (0%)	0.091	φ=0.13
Combined valve replacement	6 (5%)	2 (7%)	0.602	φ=0.04
Combined valve replacement and aorta replacement	4 (3%)	4 (13%)	0.016	φ=0.18
Combined CABG and aorta replacement	1 (1%)	0 (0%)	0.638	φ=0.03
Other	4 (3%)	0 (0%)	0.342	φ=0.07
Duration of surgery (min)	315.0±96.1	337.1±167.5	0.33	d=0.20
Blood loss volume (mL)	625.1±892.2	809.0±926.8	0.312	d=0.20
Total fluid balance (mL)	4,077.9±2,367.8	5,150.3±4,221.1	0.058	d=0.38
Heart failure	7 (5%)	2 (7%)	0.747	φ=0.02
Arrhythmia	27 (20%)	11 (37%)	0.054	φ=0.15
Major bleeding	7 (5%)	4 (13%)	0.106	φ=0.12
Renal failure	2 (1%)	3 (10%)	0.014	φ=0.19
Delirium	4 (3%)	5 (17%)	0.003	φ=0.23
Ventilation days	0 [0–1]	1.5 [0–5]	0.001	r=0.25
Length of ICU stay	4 [2–5.25]	5.5 [4–8.5]	0.001	r=0.27
Initiation of standing	2 [1–3]	4 [2–5]	<0.001	r=0.31
Initiation of walking	3 [2–4]	5.5 [4–7.75]	<0.001	r=0.34

ADL, activities of daily living; CABG, coronary artery bypass grafting; ICU, intensive care unit.

Of the patients’ preoperative and postoperative characteristics, the variables with a P value <0.05 by univariate analysis were age, sex, frailty, MMSE, CKD, OD, handgrip strength, knee extension strength, gait speed, type of surgery, renal failure, POD, ventilation days, length of ICU stay, and initiation of postoperative standing at the bedsides and walking around the bed. Initiation of postoperative standing at the bedside was excluded from the multivariate analysis because of predicted multicollinearity with initiation of postoperative walking around the bed. Therefore, age, sex, frailty, MMSE, CKD, OD, handgrip strength, knee extension strength, gait speed, type of surgery, renal failure, POD, ventilation days, length of ICU stay and initiation of postoperative walking around the bed were included in the multivariate analysis. Table 4 shows the multiple logistic regression results for decline in ADL of patients at discharge. Thus, MMSE (odds ratio (OR): 0.573, 95% confidence interval (CI): 0.420–0.783), gait speed (OR: 0.032, 95% CI: 0.003–0.304) and day of initiation of walking around the bed (OR: 1.277, 95% CI: 1.103–1.480) were independently associated with decreased ADL at discharge.

Table 4. Multiple Logistic Regression Results for Decline in ADL at Discharge

Variable	OR	95% CI	P value
Gait speed	0.032	0.003–0.304	0.003
MMSE	0.573	0.420–0.783	<0.001
Initiation of walking	1.277	1.103–1.480	0.001

ADL, activities of daily living; CI, confidence interval; MMSE, Mini-Mental State Examination; OR, odds ratio.

Using the ROC curve analysis method, an MMSE score of 27/28 was identified as the cutoff value for decreased ADL at discharge with a sensitivity of 78.3%, specificity of 60.8%, and an AUC of 0.77 (P<0.001) (Figure 2A). For gait speed, the cutoff value was 1.02 m/s with a sensitivity of 78.5%, specificity of 68.0%, and AUC of 0.76 (P<0.001) (Figure 2B). Finally, the cutoff for initiation of walking around the bed was 4–5 postoperative days, with a sensitivity of 60.8%, specificity of 75.9%, and AUC of 0.72 (P<0.001) (Figure 2C).

Figure 2.

Receiver operating characteristic (ROC) curve analysis. (A) ROC curve shows MMSE cutoff at 27/28 points with sensitivity 78.3%, specificity 60.8%, AUC 0.77. (B) ROC curve shows gait speed cutoff at 1.02 m/s with sensitivity 78.5%, specificity 68.0%, AUC 0.76. (C) ROC curve shows initiation of walking cutoff at 4–5 days with sensitivity 60.8%, specificity 75.9%, AUC 0.72. AUC, area under the curve; MMSE, Mini-Mental State Examination.

Discussion

This prospective observational study sought to identify predictors of functional decline in ADL at discharge of patients after cardiovascular surgery. To the best of our knowledge, this study is the first to report functional changes in ADL and predictors of a decline. The main finding was that preoperative cognitive function, preoperative gait speed and postoperative day of initiation of walking around the bed were independently associated with functional decline in this context.

We found that 18.1% patients undergoing cardiovascular surgery experienced decreased ADL at discharge, which is a lower proportion of patients with functional decline in ADL at discharge than reported in an earlier study.¹² This result might be explained by our inclusion of more patients with preoperative independent ADL.

Preoperative cognitive function was found to be a strong predictor of decline in ADL at discharge. Recently, a new category of cognitive dysfunction has been proposed: mild cognitive impairment (MCI). MCI is defined by the presence of clinically significant memory impairment that does not meet the criteria for dementia, or a subtle decline in other functions not related to memory,²⁷ resulting in an MMSE <27.²⁸ Thus, an MMSE score of 27/28 points was taken as the cutoff in the present study, the same as for MCI. Furthermore, MCI has been identified as an independent predictor of POD. It is known that POD is associated with short- and long-term cognitive dysfunction,²⁹ and can result in a loss of independence, escalating care needs.³⁰ It is thought that patients with preoperative cognitive impairment will have decreased long-term cognitive function and ADL after cardiovascular surgery due to the incidence of POD.

Slow gait speed was found to be an independent predictor of decreased ADL in the present study. Previous studies had already shown that preoperative gait speed is an independent predictor of operative mortality and major morbidity in patients undergoing cardiac surgery.^31,32 Our results suggested that preoperative gait speed is a predictor not only of mortality and major complications, but also of decreased ADL at discharge. Afilalo et al reported that patients with gait speed <0.83 m/s will need to be discharged to a healthcare facility for rehabilitation.³¹ Makizako et al noted that community-dwelling older adults with gait speed <1.00 m/s had a higher risk of disability.³³ Slow gait speed is 1 component of physical frailty.²³ Frail patients with slow gait are predicted to have a higher occurrence of major adverse postoperative events and increased disability. Gait speed is an effective and objective measurement of postoperative disability after cardiovascular surgery and should be incorporated into preoperative risk assessment.

Postoperative initiation of walking after cardiovascular surgery was also associated with functional decline in ADL at discharge in the present study. ROC curve analysis identified a cutoff of <4 days as important for maintaining independent ADL after cardiovascular surgery. The JCS guidelines recommend encouraging patients to start ambulation as soon as possible after cardiac surgery.¹ It is important during acute-phase rehabilitation after cardiovascular surgery that patients should be treated to stabilize hemodynamics and encouraged to begin ambulation and return to their previous level of physical activity.¹ Schweickert et al reported that early mobilization and rehabilitation intervention in intensive care could improve ADL and accelerate home discharge.³⁴ Prolonged immobility is a risk factor for muscle atrophy and ICU-acquired weakness (ICUAW). Muscle atrophic processes begin within 72 h and muscle strength is reduced by 10–30% after 1 week of bed rest.³⁵ Takahashi et al reported that muscle strength is rapidly lost during hospitalization for cardiovascular disease,³⁶ and Fan et al noted that patients with documented ICUAW had worse physical functioning and health-related quality of life.³⁷ Clearly, ICUAW affects long-term physical function and ADL after cardiovascular surgery. We consider that prolonged immobility after cardiovascular surgery could result in poorer long-term functional prognosis and decreased ADL at discharge.

We have identified several predictors of functional decline in ADL at discharge after cardiovascular surgery. Patients with a low gait speed and cognitive impairment were more likely to show a decline in ADL than those who without. Gait speed and MMSE are widely used to screen physical function and cognitive function, including frailty. Both tests preoperatively identified patients at high-risk for functional decline in ADL at discharge after cardiovascular surgery. Impairment of ADL is risk factor for prolonged length of hospital stay and decreasing likelihood of discharge to the home. Timely preoperative identification of patients at high risk for functional decline in ADL at discharge would promote coordination of care between the cardiology medical team, families and continuing care facilities. If it is known preoperatively that the patient is likely to suffer functional decline in ADL postoperatively, coordination of home-based care or decisions on transfer for rehabilitation care can be taken earlier. Recently, exercise-based interventions have been implemented in preoperative care, a process called preoperative rehabilitation. Preoperative rehabilitation seeks to maintain and enhance the physical ability of the individual to endure the stresses associated with a surgical intervention. It is assumed that preoperative rehabilitation in patients with low physical function may play an important role in preventing postoperative functional decline. Early mobilization and rehabilitation are designed to return physical activities to normal and reduce postoperative complications. However, delay in returning physical activities to normal limits the postoperative recovery of ADL during the period of acute care. Patients who are not yet able to return safely to outpatient rehabilitation programs need a longer rehabilitation program as inpatients in a rehabilitation hospital. However, in Japan there is poor cooperation between acute-care hospitals and rehabilitation hospitals.³⁸ Therefore, promoting inter-hospital cooperation on providing cardiac rehabilitation could improve patient outcomes.

Study Limitations

First, our findings were based on data from a single tertiary care center, which may limit generalizability. Second, the sample size was small, with only 166 patients. This and only 30 patients with decreased ADL at discharge were insufficient for evaluating predictors of functional decline by multivariate analysis. Third, patients with preoperative independent ADL were included, and we excluded any patients with preoperative impairments of ADL and cognitive function because we did not want to confound the predictors of functional decline in ADL at discharge after cardiovascular surgery. It is possible that some of these exclusions may have affected the results. Finally, there were differences in the length of hospital stay among the patients. With longer hospital stay, the intervention period for postoperative cardiac rehabilitation was longer. Therefore, differences in length of hospital stay had an effect on recovery of ADL at discharge.

Conclusions

Functional decrease in ADL at discharge can be predicted using preoperative cognitive function, preoperative gait speed and postoperative course of initiation of walking. Our results showed that for patients undergoing elective cardiovascular surgery, evaluation of preoperative cognitive function and gait speed can identify those who might need coordination between multiple services and cannot be immediately discharged to their homes. Furthermore, it is clear that postoperative early mobilization and rehabilitation is needed to prevent functional decline in ADL. Delay in beginning physical activity limits postoperative recovery of ADL during the time spent in the acute-care hospital. Patients with decreased ADL at this time need longer inpatient rehabilitation programs in rehabilitation facilities.

Acknowledgments

This work was supported by JSPS KAKENHI grant no. 19H00466.

Data Availability

The deidentified participant data that underlie the results reported in this article will be shared on a request basis. Please directly contact the corresponding author to request data sharing, beginning 3 months and ending 5 years after article publication.

IRB Information

Research Ethics Committee of Hyogo College of Medicine under protocol no. 201704-063.

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