In-patient step count predicts re-hospitalization after cardiac surgery.
BACKGROUND
Clinical significance of in-patient step count after cardiac surgery remains unknown. The aim of this study was to determine whether the number of steps walked during the in-patient stay after cardiac surgery predicts the risk of cardiac re-hospitalization in the following year.


METHODS
One hundred and thirty-three patients who underwent cardiac surgery were included in this study. The number of steps was assessed using a triaxial accelerometer. One year after surgery, patients completed a postal survey to determine their health condition and occurrence of cardiac re-hospitalization.


RESULTS
The mean number of steps walked during the last three in-patient days was 2460 ± 1549 (mean ± standard deviation). Of the 133 patients, there were 16 cases (12.0%) of cardiac re-hospitalization during the 1-year follow-up period. The average step count before discharge was significantly lower in the 16 patients who were re-hospitalized for cardiac causes (1297 ± 1232 versus 2620 ± 1524, p<0.01). The cut-off value that predicted the occurrence of cardiac re-hospitalization on the receiver operating curve was 1308 steps (area under the curve: 0.783, p<0.001, sensitivity: 0.814, specificity: 0.733). Cox proportional hazards analysis revealed that the strongest predictor of cardiac re-hospitalization was a low step count prior to discharge (≤1308 steps, hazard ratio: 7.58; 95% confidence interval: 2.04-28.22).


CONCLUSIONS
In-patient step count appears to be a risk factor for cardiac re-hospitalization within the first year following cardiac surgery. Further studies are needed to clarify the clinical significance of step count both preoperatively and following discharge.
School of Health Science, Tokyo University of Technology, Tokyo, Japan. Electronic address: ttakahashi@stf.teu.ac.jp.
Tetsuya
T
Takahashi
Department of Rehabilitation Medicine, Gunma Prefectural Cardiovascular Center, Maebashi, Gunma, Japan.
Megumi
M
Kumamaru
Lung Institute of Western Australia, Perth, Australia; Physiotherapy Department, Sir Charles Gairdner Hospital, Perth, Australia; School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia.
Sue
S
Jenkins
Department of Physical Therapy, Sakakibara Heart Institute, Fuchu, Tokyo, Japan.
Masakazu
M
Saitoh
School of Rehabilitation, Hyogo University of Health Sciences, Kobe, Hyogo, Japan.
Tomoyuki
T
Morisawa
School of Rehabilitation, Hyogo University of Health Sciences, Kobe, Hyogo, Japan.
Hikaru
H
Matsuda
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000534:rehabilitation / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D010359:Patient Readmission / Q000706:statistics & numerical data*; D011182:Postoperative Care / Q000379:methods / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D012307:Risk Factors; D016138:Walking / Q000706:statistics & numerical data*
Cardiac surgery; Re-hospitalization; Rehabilitation; Step count