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Preoperative physical activity in relation to postoperative delirium in elective cardiac surgery patients
International Journal of Cardiology 201 (2015) 154–156
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Preoperative physical activity in relation to postoperative delirium in elective cardiac surgery patients Masato Ogawa a,b, Kazuhiro P. Izawa b,⁎, Aki Kitamura c, Rei Ono b, Seimi Satomi-Kobayashi d, Yoshitada Sakai e, Yutaka Okita c a
Division of Rehabilitation Medicine, Kobe University Hospital, Kobe, Japan Kobe University Graduate School of Health Sciences, Kobe, Japan c Division of Cardiovascular Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan d Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan e Division of Rehabilitation Medicine, Kobe University Graduate School of Medicine, Kobe, Japan b
a r t i c l e
i n f o
Article history: Received 25 June 2015 Accepted 27 June 2015 Available online 2 July 2015 Keywords: Physical activity Postoperative Delirium Elective cardiac surgery
Postoperative delirium is a common and critical complication [1]. Previous studies have demonstrated that postoperative delirium occurs in as many as 20–25% of cardiac surgery patients [2,3]. Not only does postoperative delirium frequently affect cardiac patients, but it is also associated with poor outcomes such as persistent functional decline, extended hospital stay, high cost, cognitive impairment, mortality and major morbidities [4,5]. The first crucial step in postoperative delirium prevention is the identification of patients who are at risk. Several studies have shown that the inability to complete one or more ADLs increases the risk of postoperative delirium [6,7]. The interaction between specific physical activities and postoperative delirium has not been satisfactorily explored. Thus, we hypothesized that poor preoperative physical activity is correlated with the incidence of postoperative delirium. The purpose of this study is to determine whether preoperative physical activities have a positive predictive value for postoperative delirium. This study included 144 consecutive patients who were from 21–89 years of age, who were admitted to the ICU after elective cardiac surgery at Kobe University Hospital from September 2013 to April 2015. Patients who underwent emergency cardiac surgery, had a history of neurological or orthopedic disease, or who were diagnosed with de⁎ Corresponding author at: Graduate School of Health Sciences, Kobe University, 10-2 Tomogaoka 7-chomo Suma, Kobe 654-0142, Japan. E-mail address: [email protected] (K.P. Izawa).
http://dx.doi.org/10.1016/j.ijcard.2015.06.154 0167-5273/© 2015 Elsevier Ireland Ltd. All rights reserved.
mentia before surgery were excluded from the study. Patient characteristics including age, sex, BMI, left ventricular ejection fraction (EF), plasma brain natriuretic peptide (BNP) concentration, estimated GFR (eGFR), comorbidities, intra-operative course, postoperative length of stay in the ICU, postoperative arrhythmia, and postoperative complications were evaluated by a review of the patients' medical records. We measured physical activity by Life Space Assessment (LSA), which is a validated questionnaire assessing global mobility from the patient's perspective, with respect to activities in the home environment and in the community over the previous four weeks [8]. The LSA was performed four weeks before surgery. Delirium assessments were conducted every 8 h by trained nurses from the day of surgery to 5 days after surgery using the ICDSC [9]. The ICDSC is a delirium assessment tool that was created for medical professionals other than psychiatrists. The present study was approved by the Kobe University Institutional Committee on Human Research. Written, informed consent was obtained from each patient. Results are expressed as the mean ± standard deviation (SD). Differences between variables that were possibly related to the development of delirium were analyzed by unpaired t-test or χ2test. A logistic regression analysis was used to examine the association between the incidence of delirium and each variable. In this analysis, the incidence of delirium was used as the dependent variable. The clinical characteristics and physical activities were independent variables. Confounding factors were those that were significantly different (P b 0.05) in the bivariate analyses. The final logistic regression model was developed by forward stepwise selection from all variables that were significantly associated with postoperative delirium in the bivariate analyses (P b 0.05). Receiver operating characteristic (ROC) curves were constructed by plotting true-positive rates (sensitivity) against false-positive rates (1-specificity) to determine the best cut-off LSA values. The area under the curve (AUC) and 95% confidence interval (CI) were also calculated. AUC values of N0.9 show high accuracy, 0.7–0.9 show moderate accuracy and b 0.7 show low accuracy [10]. The overall statistical significance level was set at 0.05. All statistical analyses were performed using the JMP 11.0J software program (SAS Institute Japan, Tokyo, Japan). Eighty of the 144 (55.6%) patients were male. The mean age was 64.8 ± 16.4 years. The types of surgery were as follows: valve surgery (n = 110, 76.3%), valve and CABG surgery (n = 34, 23.6%). Among the 144 patients, 14
Letter to the Editor
155
Table 1 Comparison of the preoperative, intraoperative and postoperative risk factors for delirium.
No. (%) Age, years Male, n (%) Body mass index, kg/m2 Ejection fraction, % Laboratory data Brain natriuretic peptide, pg/ml eGFR, ml/min/1.73 m Hemoglobin, g/dl Albumin, g/dl Comorbidities Atrial fibrillation Hypertension Hyperlipidemia Diabetes Euroscore II LSA Duration of anesthesia, min Duration of surgery, min Duration of CPB, min Aortic cross clamp time, min Fluid balance, ml New onset postoperative atrial fibrillation, n (%) Length of ICU stay, day Postoperative complication, n (%)
Total
Delirium present
Delirium absent
P value
144 64.8 ± 16.4 80 (55.6) 22.9 ± 3.8 59.0 ± 11.9
14 (9.7) 70.5 ± 15.2 6 (42.9) 23.2 ± 3.3 57.2 ± 16.7
130 (90.3) 64.9 ± 16.1 74 (56.5) 22.8 ± 3.9 59.8 ± 11.5
0.21 0.33 0.7 0.51
368.9 ± 160.2 62.0 ± 21.2 12.3 ± 2.0 4.0 ± 0.5
356.9 ± 120.5 53.2 ± 23.2 11.3 ± 1.5 3.9 ± 0.5
374.8 ± 121.4 63.8 ± 20.8 12.7 ± 2.0 4.0 ± 0.5
0.5 0.04⁎ 0.02⁎ 0.58
25 (17.4) 80 (55.6) 40 (27.8) 29 (20.1) 6.4 ± 2.3 81.8 ± 33.3 451.3 ± 147.4 371.0 ± 131.4 180.0 ± 87.4 112.1 ± 79.3 2439.9 ± 3810.0 50 (34.7) 3.6 ± 2.0 24 (16.7)
3 (23.1) 8 (61.5) 1 (7.7) 2 (15.4) 6.9 ± 2.6 55.9 ± 21.6 462.6 ± 220.5 403.2 ± 158.1 165.7 ± 110.3 89.3 ± 60.5 4132.7 ± 3917.3 7 (50) 4.8 ± 2.8 7 (50.0)
22 (16.8) 72 (55.0) 39 (30.0) 27 (20.3) 6.3 ± 2.6 81.9 ± 35.0 446.4 ± 140.0 367.4 ± 122.2 117.0 ± 78.5 117.2 ± 83.0 2228.1 ± 4124.6 43 (35.6) 3.4 ± 2.8 17 (14.0)
0.58 0.64 0.06 0.64 0.33 0.01⁎ 0.70 0.33 0.64 0.24 0.12 0.30 0.01⁎
0.003⁎
eGFR, estimated glomerular filtration rate; LSA, life-space assessment. ⁎ Statistically significant difference.
patients (9.7%) experienced postoperative delirium. The patients were divided into two groups based on the presence or absence of postoperative delirium. With the exception of serum hemoglobin, eGFR and LSA, the patient characteristics of the two groups were similar (Table 1); regarding the intraoperative and postoperative factors, the postoperative length of stay in the ICU and postoperative complications differed significantly between the two groups (Table 1). LSA remained a statistically significant factor in a multivariate analysis that adjusted for serum hemoglobin, eGFR, LSA and postoperative length of stay in ICU as confounding factors (Table 2). The cut-off values for LSA determined by the ROC curve analysis were LSA: 84 (sensitivity, 0.90; specificity, 0.63; AUC = 0.77; 95% CI, 1.01–1.04; P = 0.02) (Fig. 1) To our knowledge, this is the first report to identify physical activity measured by LSA as an independent risk factor of delirium after cardiac surgery. After adjustment for patients' characteristics, including serum hemoglobin and eGFR, low preoperative LSA scores were strongly associated with the incidence of postoperative delirium. LSA was validated to assess mobility and participation in society with respect to activity in the home environment and the surrounding community. LSA assessment in the perioperative setting shows higher sensitivity than the ADLs in identifying elderly adults who are at risk for further decline in functional capacity and mobility after elective surgery [11].
Furthermore, previous studies reported that life-space is larger in patients with better physical performance, cognitive function, mental health, and environmental/psychosocial status [12]. Therefore, in addition to assessing physical functions and daily activities, LSA might also reflect social interaction and psychosocial background. Preoperative cognitive impairment and physical frailty are reported to be important risk factors for postoperative delirium [13]. LSA might be a useful and sensitive indicator that allows physicians to see through the initial physical/psychological decline. The cut-off value for the LSA (84 points) is lower than the values of elderly Japanese individuals (95.5 ± 17.6) [14]. The AUC of the ROC curve was 0.77, which indicates moderate accuracy. Xue et al. [15] demonstrated that compared to women who left
LSA: 84 points
Sensitivity Table 2 The multivariate analysis of the risk factors for the development of postoperative delirium. Variables
Hemoglobin LSA eGFR ICU stay
Model 1
Model 2
OR (95%CI)
P value
OR (95% CI)
P value
0.74 (0.18–0.97) 0.97 (0.95–0.99) 0.97 (0.96–1.02) 1.3 (1.2–2.2)
0.04⁎ 0.01⁎ 0.12 0.03⁎
0.98 (0.97–0.99)
0.04⁎
1.2 (0.99–1.53)
0.08
The logistic regression analyses were conducted with delirium present/delirium absent as the dependent variable. The clinical characteristics, pre-, intra-, post-operative risk factors and, physical activity scores were included as independent variables. Model 1 shows the crude odds ratios obtained in the bivariate analyses for each independent variable. Model 2 was developed by stepwise variable selection. eGFR, estimated glomerular filtration rate; OR, odds ratio; CI, confidence interval. ⁎ Statistically significant difference.
1-Specificity Fig. 1. The ROC curve of the LSA to predict the incidence of postoperative delirium. The AUC is 0.77 with the LSA set at 84, which is indicative of an increased risk for postoperative delirium (sensitivity 90%, specificity 63%). P = 0.002, 95% CI; 1.01–1.04. ROC, receiver operating characteristic; LSA, life space assessment; AUC, area under the curve.
156
Letter to the Editor
the neighborhood ≥4 times per week, those who left the neighborhood less frequently were 1.7 times more likely to become frail; those who never left their homes experienced a three-fold increase in frailty-free mortality. Loss or difficulty in social roles resulted in a restriction of life-space, leading to decreased physical activity, and the deterioration of daily life functions. Other than LSA, preoperative anemia and poor kidney function tended to be associated with postoperative delirium. Anemia and poor kidney function were previously reported as predictors of postoperative delirium because they often cause dehydration or the requirement for blood transfusion [13]. The present study was associated with several limitations. The study population was relatively small. Consequently, we could not analyze sex- or age-related differences. Furthermore, we did not assess postoperative risk factors such as adverse drug reactions, pain control, and the use of restraints. Although there are routine protocols for postoperative pain control and sedation in our ICU, it is difficult to know whether such medications are a cause or effect of delirium. In conclusion, preoperative functional status and life-space mobility assessed by LSA were strongly associated with the incidence of postoperative delirium in elective cardiac surgery and might be useful as minimum target goals for preoperative rehabilitation. Conflict of interest The authors declare that there are no conflicts of interest. References [1] J.L. Rudolph, S.K. Inouye, R.N. Jones, F.M. Yang, T.G. Fong, S.E. Levkoff, E.R. Marcantonio, Delirium: an independent predictor of functional decline after cardiac surgery, J. Am. Geriatr. Soc. 58 (2010) 643–649.
[2] S. Sockalingam, N. Parekh, I.I. Bogoch, J. Sun, R. Mahtani, C. Beach, N. Bollegalla, S. Turzanski, E. Seto, J. Kim, P. Dulay, S. Scarrow, S. Bhalerao, Delirium in the postoperative cardiac patient: a review, J. Card. Surg. 20 (2005) 560–567. [3] S.P. Clarke, M.E. McRae, S. Del Signore, M. Schubert, R. Styra, Delirium in older cardiac surgery patients: directions for practice, J. Gerontol. Nurs. 36 (2010) 34–45. [4] Y. Shehabi, R.R. Riker, P.M. Bokesch, W. Wisemandle, A. Shintani, E.W. Ely, Delirium duration and mortality in lightly sedated, mechanically ventilated intensive care patients, Crit. Care Med. 38 (2010) 2311–2318. [5] K. Franco, D. Litaker, J. Locala, D. Bronson, The cost of delirium in the surgical patient, Psychosomatics 42 (2001) 68–73. [6] P. Galanakis, H. Bickel, R. Gradinger, S. Von Gumppenberg, H. Förstl, Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications, Int. J. Geriatr. Psychiatry 16 (2001) 349–355. [7] D. Litaker, J. Locala, K. Franco, D.L. Bronson, Z. Tannous, Preoperative risk factors for postoperative delirium, Gen. Hosp. Psychiatry 23 (2001) 84–89. [8] P.S. Baker, E.V. Bodner, R.M. Allman, Measuring life-space mobility in communitydwelling older adults, J. Am. Geriatr. Soc. 51 (2003) 1610–1614. [9] N. Bergeron, M.J. Dubois, M. Dumont, S. Dial, Y. Skrobik, Intensive Care Delirium Screening Checklist: evaluation of a new screening tool, Intensive Care Med. 27 (2001) 859–864. [10] A.K. Akobeng, Understanding diagnostic tests 3: receiver operating characteristic curves, Acta Paediatr. 96 (2007) 644–647. [11] C.M. Stewart, T.L. Wheeler II, A.D. Markland, J.M. Straughn Jr., H.E. Richter, Life-space assessment in urogynecology and gynecological oncology surgery patients: a measure of perioperative mobility and function, J. Am. Geriatr. Soc. 57 (2009) 2263–2268. [12] C. Murata, T. Kondo, K. Tamakoshi, H. Yatsuya, H. Toyoshima, Factors associated with life space among community-living rural elders in Japan, Public Health Nurs. 23 (2006) 324–331. [13] I.J. Zaal, J.W. Devlin, L.M. Peelen, A.J. Slooter, A systematic review of risk factors for delirium in the ICU, Crit. Care Med. 43 (2015) 40–47. [14] T. Oya, Y. Uchiyama, H. Shimada, H. Makizako, T. Doi, D. Yoshida, K. Uemura, T. Suzuki, Factors associated with fear of falling among community-dwelling elderly adults without reduced performance in instrumental activities of daily living, Nihon Ronen Igakkai Zasshi 49 (2012) 457–462 (Japanese with English abstract). [15] Q.L. Xue, L.P. Fried, T.A. Glass, A. Laffan, P.H. Chaves, Life-space constriction, development of frailty, and the competing risk of mortality: the Women's Health and Aging Study I, Am. J. Epidemiol. 167 (2007) 240–248.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Preoperative physical activity in relation to postoperative delirium in elective cardiac surgery patients Masato Ogawa a,b, Kazuhiro P. Izawa b,⁎, Aki Kitamura c, Rei Ono b, Seimi Satomi-Kobayashi d, Yoshitada Sakai e, Yutaka Okita c a
Division of Rehabilitation Medicine, Kobe University Hospital, Kobe, Japan Kobe University Graduate School of Health Sciences, Kobe, Japan c Division of Cardiovascular Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan d Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan e Division of Rehabilitation Medicine, Kobe University Graduate School of Medicine, Kobe, Japan b
a r t i c l e
i n f o
Article history: Received 25 June 2015 Accepted 27 June 2015 Available online 2 July 2015 Keywords: Physical activity Postoperative Delirium Elective cardiac surgery
Postoperative delirium is a common and critical complication [1]. Previous studies have demonstrated that postoperative delirium occurs in as many as 20–25% of cardiac surgery patients [2,3]. Not only does postoperative delirium frequently affect cardiac patients, but it is also associated with poor outcomes such as persistent functional decline, extended hospital stay, high cost, cognitive impairment, mortality and major morbidities [4,5]. The first crucial step in postoperative delirium prevention is the identification of patients who are at risk. Several studies have shown that the inability to complete one or more ADLs increases the risk of postoperative delirium [6,7]. The interaction between specific physical activities and postoperative delirium has not been satisfactorily explored. Thus, we hypothesized that poor preoperative physical activity is correlated with the incidence of postoperative delirium. The purpose of this study is to determine whether preoperative physical activities have a positive predictive value for postoperative delirium. This study included 144 consecutive patients who were from 21–89 years of age, who were admitted to the ICU after elective cardiac surgery at Kobe University Hospital from September 2013 to April 2015. Patients who underwent emergency cardiac surgery, had a history of neurological or orthopedic disease, or who were diagnosed with de⁎ Corresponding author at: Graduate School of Health Sciences, Kobe University, 10-2 Tomogaoka 7-chomo Suma, Kobe 654-0142, Japan. E-mail address: [email protected] (K.P. Izawa).
http://dx.doi.org/10.1016/j.ijcard.2015.06.154 0167-5273/© 2015 Elsevier Ireland Ltd. All rights reserved.
mentia before surgery were excluded from the study. Patient characteristics including age, sex, BMI, left ventricular ejection fraction (EF), plasma brain natriuretic peptide (BNP) concentration, estimated GFR (eGFR), comorbidities, intra-operative course, postoperative length of stay in the ICU, postoperative arrhythmia, and postoperative complications were evaluated by a review of the patients' medical records. We measured physical activity by Life Space Assessment (LSA), which is a validated questionnaire assessing global mobility from the patient's perspective, with respect to activities in the home environment and in the community over the previous four weeks [8]. The LSA was performed four weeks before surgery. Delirium assessments were conducted every 8 h by trained nurses from the day of surgery to 5 days after surgery using the ICDSC [9]. The ICDSC is a delirium assessment tool that was created for medical professionals other than psychiatrists. The present study was approved by the Kobe University Institutional Committee on Human Research. Written, informed consent was obtained from each patient. Results are expressed as the mean ± standard deviation (SD). Differences between variables that were possibly related to the development of delirium were analyzed by unpaired t-test or χ2test. A logistic regression analysis was used to examine the association between the incidence of delirium and each variable. In this analysis, the incidence of delirium was used as the dependent variable. The clinical characteristics and physical activities were independent variables. Confounding factors were those that were significantly different (P b 0.05) in the bivariate analyses. The final logistic regression model was developed by forward stepwise selection from all variables that were significantly associated with postoperative delirium in the bivariate analyses (P b 0.05). Receiver operating characteristic (ROC) curves were constructed by plotting true-positive rates (sensitivity) against false-positive rates (1-specificity) to determine the best cut-off LSA values. The area under the curve (AUC) and 95% confidence interval (CI) were also calculated. AUC values of N0.9 show high accuracy, 0.7–0.9 show moderate accuracy and b 0.7 show low accuracy [10]. The overall statistical significance level was set at 0.05. All statistical analyses were performed using the JMP 11.0J software program (SAS Institute Japan, Tokyo, Japan). Eighty of the 144 (55.6%) patients were male. The mean age was 64.8 ± 16.4 years. The types of surgery were as follows: valve surgery (n = 110, 76.3%), valve and CABG surgery (n = 34, 23.6%). Among the 144 patients, 14
Letter to the Editor
155
Table 1 Comparison of the preoperative, intraoperative and postoperative risk factors for delirium.
No. (%) Age, years Male, n (%) Body mass index, kg/m2 Ejection fraction, % Laboratory data Brain natriuretic peptide, pg/ml eGFR, ml/min/1.73 m Hemoglobin, g/dl Albumin, g/dl Comorbidities Atrial fibrillation Hypertension Hyperlipidemia Diabetes Euroscore II LSA Duration of anesthesia, min Duration of surgery, min Duration of CPB, min Aortic cross clamp time, min Fluid balance, ml New onset postoperative atrial fibrillation, n (%) Length of ICU stay, day Postoperative complication, n (%)
Total
Delirium present
Delirium absent
P value
144 64.8 ± 16.4 80 (55.6) 22.9 ± 3.8 59.0 ± 11.9
14 (9.7) 70.5 ± 15.2 6 (42.9) 23.2 ± 3.3 57.2 ± 16.7
130 (90.3) 64.9 ± 16.1 74 (56.5) 22.8 ± 3.9 59.8 ± 11.5
0.21 0.33 0.7 0.51
368.9 ± 160.2 62.0 ± 21.2 12.3 ± 2.0 4.0 ± 0.5
356.9 ± 120.5 53.2 ± 23.2 11.3 ± 1.5 3.9 ± 0.5
374.8 ± 121.4 63.8 ± 20.8 12.7 ± 2.0 4.0 ± 0.5
0.5 0.04⁎ 0.02⁎ 0.58
25 (17.4) 80 (55.6) 40 (27.8) 29 (20.1) 6.4 ± 2.3 81.8 ± 33.3 451.3 ± 147.4 371.0 ± 131.4 180.0 ± 87.4 112.1 ± 79.3 2439.9 ± 3810.0 50 (34.7) 3.6 ± 2.0 24 (16.7)
3 (23.1) 8 (61.5) 1 (7.7) 2 (15.4) 6.9 ± 2.6 55.9 ± 21.6 462.6 ± 220.5 403.2 ± 158.1 165.7 ± 110.3 89.3 ± 60.5 4132.7 ± 3917.3 7 (50) 4.8 ± 2.8 7 (50.0)
22 (16.8) 72 (55.0) 39 (30.0) 27 (20.3) 6.3 ± 2.6 81.9 ± 35.0 446.4 ± 140.0 367.4 ± 122.2 117.0 ± 78.5 117.2 ± 83.0 2228.1 ± 4124.6 43 (35.6) 3.4 ± 2.8 17 (14.0)
0.58 0.64 0.06 0.64 0.33 0.01⁎ 0.70 0.33 0.64 0.24 0.12 0.30 0.01⁎
0.003⁎
eGFR, estimated glomerular filtration rate; LSA, life-space assessment. ⁎ Statistically significant difference.
patients (9.7%) experienced postoperative delirium. The patients were divided into two groups based on the presence or absence of postoperative delirium. With the exception of serum hemoglobin, eGFR and LSA, the patient characteristics of the two groups were similar (Table 1); regarding the intraoperative and postoperative factors, the postoperative length of stay in the ICU and postoperative complications differed significantly between the two groups (Table 1). LSA remained a statistically significant factor in a multivariate analysis that adjusted for serum hemoglobin, eGFR, LSA and postoperative length of stay in ICU as confounding factors (Table 2). The cut-off values for LSA determined by the ROC curve analysis were LSA: 84 (sensitivity, 0.90; specificity, 0.63; AUC = 0.77; 95% CI, 1.01–1.04; P = 0.02) (Fig. 1) To our knowledge, this is the first report to identify physical activity measured by LSA as an independent risk factor of delirium after cardiac surgery. After adjustment for patients' characteristics, including serum hemoglobin and eGFR, low preoperative LSA scores were strongly associated with the incidence of postoperative delirium. LSA was validated to assess mobility and participation in society with respect to activity in the home environment and the surrounding community. LSA assessment in the perioperative setting shows higher sensitivity than the ADLs in identifying elderly adults who are at risk for further decline in functional capacity and mobility after elective surgery [11].
Furthermore, previous studies reported that life-space is larger in patients with better physical performance, cognitive function, mental health, and environmental/psychosocial status [12]. Therefore, in addition to assessing physical functions and daily activities, LSA might also reflect social interaction and psychosocial background. Preoperative cognitive impairment and physical frailty are reported to be important risk factors for postoperative delirium [13]. LSA might be a useful and sensitive indicator that allows physicians to see through the initial physical/psychological decline. The cut-off value for the LSA (84 points) is lower than the values of elderly Japanese individuals (95.5 ± 17.6) [14]. The AUC of the ROC curve was 0.77, which indicates moderate accuracy. Xue et al. [15] demonstrated that compared to women who left
LSA: 84 points
Sensitivity Table 2 The multivariate analysis of the risk factors for the development of postoperative delirium. Variables
Hemoglobin LSA eGFR ICU stay
Model 1
Model 2
OR (95%CI)
P value
OR (95% CI)
P value
0.74 (0.18–0.97) 0.97 (0.95–0.99) 0.97 (0.96–1.02) 1.3 (1.2–2.2)
0.04⁎ 0.01⁎ 0.12 0.03⁎
0.98 (0.97–0.99)
0.04⁎
1.2 (0.99–1.53)
0.08
The logistic regression analyses were conducted with delirium present/delirium absent as the dependent variable. The clinical characteristics, pre-, intra-, post-operative risk factors and, physical activity scores were included as independent variables. Model 1 shows the crude odds ratios obtained in the bivariate analyses for each independent variable. Model 2 was developed by stepwise variable selection. eGFR, estimated glomerular filtration rate; OR, odds ratio; CI, confidence interval. ⁎ Statistically significant difference.
1-Specificity Fig. 1. The ROC curve of the LSA to predict the incidence of postoperative delirium. The AUC is 0.77 with the LSA set at 84, which is indicative of an increased risk for postoperative delirium (sensitivity 90%, specificity 63%). P = 0.002, 95% CI; 1.01–1.04. ROC, receiver operating characteristic; LSA, life space assessment; AUC, area under the curve.
156
Letter to the Editor
the neighborhood ≥4 times per week, those who left the neighborhood less frequently were 1.7 times more likely to become frail; those who never left their homes experienced a three-fold increase in frailty-free mortality. Loss or difficulty in social roles resulted in a restriction of life-space, leading to decreased physical activity, and the deterioration of daily life functions. Other than LSA, preoperative anemia and poor kidney function tended to be associated with postoperative delirium. Anemia and poor kidney function were previously reported as predictors of postoperative delirium because they often cause dehydration or the requirement for blood transfusion [13]. The present study was associated with several limitations. The study population was relatively small. Consequently, we could not analyze sex- or age-related differences. Furthermore, we did not assess postoperative risk factors such as adverse drug reactions, pain control, and the use of restraints. Although there are routine protocols for postoperative pain control and sedation in our ICU, it is difficult to know whether such medications are a cause or effect of delirium. In conclusion, preoperative functional status and life-space mobility assessed by LSA were strongly associated with the incidence of postoperative delirium in elective cardiac surgery and might be useful as minimum target goals for preoperative rehabilitation. Conflict of interest The authors declare that there are no conflicts of interest. References [1] J.L. Rudolph, S.K. Inouye, R.N. Jones, F.M. Yang, T.G. Fong, S.E. Levkoff, E.R. Marcantonio, Delirium: an independent predictor of functional decline after cardiac surgery, J. Am. Geriatr. Soc. 58 (2010) 643–649.
[2] S. Sockalingam, N. Parekh, I.I. Bogoch, J. Sun, R. Mahtani, C. Beach, N. Bollegalla, S. Turzanski, E. Seto, J. Kim, P. Dulay, S. Scarrow, S. Bhalerao, Delirium in the postoperative cardiac patient: a review, J. Card. Surg. 20 (2005) 560–567. [3] S.P. Clarke, M.E. McRae, S. Del Signore, M. Schubert, R. Styra, Delirium in older cardiac surgery patients: directions for practice, J. Gerontol. Nurs. 36 (2010) 34–45. [4] Y. Shehabi, R.R. Riker, P.M. Bokesch, W. Wisemandle, A. Shintani, E.W. Ely, Delirium duration and mortality in lightly sedated, mechanically ventilated intensive care patients, Crit. Care Med. 38 (2010) 2311–2318. [5] K. Franco, D. Litaker, J. Locala, D. Bronson, The cost of delirium in the surgical patient, Psychosomatics 42 (2001) 68–73. [6] P. Galanakis, H. Bickel, R. Gradinger, S. Von Gumppenberg, H. Förstl, Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications, Int. J. Geriatr. Psychiatry 16 (2001) 349–355. [7] D. Litaker, J. Locala, K. Franco, D.L. Bronson, Z. Tannous, Preoperative risk factors for postoperative delirium, Gen. Hosp. Psychiatry 23 (2001) 84–89. [8] P.S. Baker, E.V. Bodner, R.M. Allman, Measuring life-space mobility in communitydwelling older adults, J. Am. Geriatr. Soc. 51 (2003) 1610–1614. [9] N. Bergeron, M.J. Dubois, M. Dumont, S. Dial, Y. Skrobik, Intensive Care Delirium Screening Checklist: evaluation of a new screening tool, Intensive Care Med. 27 (2001) 859–864. [10] A.K. Akobeng, Understanding diagnostic tests 3: receiver operating characteristic curves, Acta Paediatr. 96 (2007) 644–647. [11] C.M. Stewart, T.L. Wheeler II, A.D. Markland, J.M. Straughn Jr., H.E. Richter, Life-space assessment in urogynecology and gynecological oncology surgery patients: a measure of perioperative mobility and function, J. Am. Geriatr. Soc. 57 (2009) 2263–2268. [12] C. Murata, T. Kondo, K. Tamakoshi, H. Yatsuya, H. Toyoshima, Factors associated with life space among community-living rural elders in Japan, Public Health Nurs. 23 (2006) 324–331. [13] I.J. Zaal, J.W. Devlin, L.M. Peelen, A.J. Slooter, A systematic review of risk factors for delirium in the ICU, Crit. Care Med. 43 (2015) 40–47. [14] T. Oya, Y. Uchiyama, H. Shimada, H. Makizako, T. Doi, D. Yoshida, K. Uemura, T. Suzuki, Factors associated with fear of falling among community-dwelling elderly adults without reduced performance in instrumental activities of daily living, Nihon Ronen Igakkai Zasshi 49 (2012) 457–462 (Japanese with English abstract). [15] Q.L. Xue, L.P. Fried, T.A. Glass, A. Laffan, P.H. Chaves, Life-space constriction, development of frailty, and the competing risk of mortality: the Women's Health and Aging Study I, Am. J. Epidemiol. 167 (2007) 240–248.