Sun-wook Kim

Multidimensional Frailty Score for the Prediction of Postoperative Mortality Risk

IMPORTANCE The number of geriatric patients who undergo surgery has been increasing, but there are insufficient tools to predict postoperative outcomes in the elderly. OBJECTIVE To design a predictive model for adverse outcomes in older surgical patients. DESIGN, SETTING, AND PARTICIPANTS From October 19, 2011, to July 31, 2012, a single tertiary care center enrolled 275 consecutive elderly patients (aged ≥65 years) undergoing intermediate-risk or high-risk elective operations in the Department of Surgery. MAIN OUTCOMES AND MEASURES The primary outcome was the 1-year all-cause mortality rate. The secondary outcomes were postoperative complications (eg, pneumonia, urinary tract infection, delirium, acute pulmonary thromboembolism, and unplanned intensive care unit admission), length of hospital stay, and discharge to nursing facility. RESULTS Twenty-five patients (9.1%) died during the follow-up period (median [interquartile range], 13.3 [11.5-16.1] months), including 4 in-hospital deaths after surgery. Twenty-nine patients (10.5%) experienced at least 1 complication after surgery and 24 (8.7%) were discharged to nursing facilities. Malignant disease and low serum albumin levels were more common in the patients who died. Among the geriatric assessment domains, Charlson Comorbidity Index, dependence in activities of daily living, dependence in instrumental activities of daily living, dementia, risk of delirium, short midarm circumference, and malnutrition were associated with increased mortality rates. A multidimensional frailty score model composed of the above items predicted all-cause mortality rates more accurately than the American Society of Anesthesiologists classification (area under the receiver operating characteristic curve, 0.821 vs 0.647; P = .01). The sensitivity and specificity for predicting all-cause mortality rates were 84.0% and 69.2%, respectively, according to the models cutoff point (>5 vs ≤5). High-risk patients (multidimensional frailty score >5) showed increased postoperative mortality risk (hazard ratio, 9.01; 95% CI, 2.15-37.78; P = .003) and longer hospital stays after surgery (median [interquartile range], 9 [5-15] vs 6 [3-9] days; P < .001). CONCLUSIONS AND RELEVANCE The multidimensional frailty score based on comprehensive geriatric assessment is more useful than conventional methods for predicting outcomes in geriatric patients undergoing surgery.

Prevalence and Outcomes of Frailty in Korean Elderly Population: Comparisons of a Multidimensional Frailty Index with Two Phenotype Models

Background Frailty is related to adverse outcomes in the elderly. However, current status and clinical significance of frailty have not been evaluated for the Korean elderly population. We aimed to investigate the usefulness of established frailty criteria for community-dwelling Korean elderly. We also tried to develop and validate a new frailty index based on a multidimensional model. Methods We studied 693 participants of the Korean Longitudinal Study on Health and Aging (KLoSHA). We developed a new frailty index (KLoSHA Frailty Index, KFI) and compared predictability of it with the established frailty indexes from the Cardiovascular Health Study (CHS) and Study of Osteoporotic Fracture (SOF). Mortality, hospitalization, and functional decline were evaluated. Results The prevalence of frailty was 9.2% (SOF index), 13.2% (CHS index), and 15.6% (KFI). The criteria from CHS and KFI correlated with each other, but SOF did not correlate with KFI. During the follow-up period (5.6±0.9 years), 97 participants (14.0%) died. Frailty defined by KFI predicted mortality better than CHS index (c-index: 0.713 and 0.596, respectively; p<0.001, better for KFI). In contrast, frailty by SOF index was not related to mortality. The KFI showed better predictability for following functional decline than CHS index (area under the receiver-operating characteristic curve was 0.937 for KFI and 0.704 for CHS index, p = 0.001). However, the SOF index could not predict subsequent functional decline. Frailty by the KFI (OR = 2.13, 95% CI 1.04–4.35) and CHS index (OR = 2.24, 95% CI 1.05–4.76) were associated with hospitalization. In contrast, frailty by the SOF index was not correlated with hospitalization (OR = 1.43, 95% CI 0.68–3.01). Conclusion Prevalence of frailty was higher in Korea compared to previous studies in other countries. A novel frailty index (KFI), which includes domains of comprehensive geriatric assessment, is a valid criterion for the evaluation and prediction of frailty in the Korean elderly population.

Prediction of Postoperative Complications Using Multidimensional Frailty Score in Older Female Cancer Patients with American Society of Anesthesiologists Physical Status Class 1 or 2.

BACKGROUND Even low-risk, elderly patients are at increased risk for postoperative morbidity compared with their younger counterparts. We sought to evaluate the role of a scoring model in predicting adverse surgical outcomes in low-risk, older, female cancer patients. STUDY DESIGN From October 2011 to May 2014, two hundred and eighty-one low-risk female patients (aged 65 years and older, American Society of Anesthesiologists class 1 or 2) undergoing curative cancer surgery were included. The Multidimensional Frailty Score (MFS) was calculated by comprehensive geriatric assessment. The primary end point was postoperative complication (eg, pneumonia, urinary tract infection, delirium, acute pulmonary thromboembolism, and unplanned ICU admission). Secondary outcomes were length of hospital stay and institutionalization. RESULTS Twenty patients experienced postoperative complications and 15 patients were discharged to nursing facilities. The fully adjusted odds ratio (OR) per 1-point increase in MFS was 1.412 (95% CI, 1.012-1.969; p = 0.042) for postoperative complications, 1.377 (95% CI, 0.935-2.026; p = 0.105) for institutionalization, and 1.411 (95% CI, 1.110-1.793; p = 0.005) for prolonged hospital stay. The high-risk group (MFS ≥7) showed an increased risk for postoperative complications (OR = 8.513; 95% CI, 2.210-32.785; p = 0.002), institutionalization (OR = 1.291; 95% CI, 0.324-5.152; p = 0.717), and prolonged hospital stay (OR = 2.336; 95% CI, 1.090-5.006; p = 0.029) compared with the low-risk group (MFS <7), after adjusting confounders. CONCLUSIONS Multidimensional Frailty Score based on a preoperative comprehensive geriatric assessment is useful for predicting postoperative complications and prolonged hospital stay, even in low-risk elderly women who are undergoing cancer surgery.

The Korean version of the FRAIL scale: clinical feasibility and validity of assessing the frailty status of Korean elderly

Background/Aims: The fatigue, resistance, ambulation, illnesses, and loss of weight (FRAIL) scale is a screening tool for frailty status using a simple 5-item questionnaire. The aim of this study was to evaluate the clinical feasibility and validity of the Korean version of the FRAIL (K-FRAIL) scale. Methods: Questionnaire items were translated and administered to 103 patients aged ≥ 65 years who underwent a comprehensive geriatric assessment at the Seoul National University Bundang Hospital. In this cross-sectional study, the K-FRAIL scale was compared with the domains and the multidimensional frailty index of the comprehensive geriatric assessment. We also assessed the time required to complete the scale. Results: The participants’ mean age was 76.8 years (standard deviation [SD], 6.1), and 55 (53.4%) were males. The mean overall frailty index was 0.19 (SD, 0.17). For K-FRAIL-robust, prefrail, and frail patients, the mean frailty indices were 0.09, 0.18, and 0.34, respectively (p for trend < 0.001). A higher degree of impairment in the K-FRAIL scale was associated with worse nutritional status, poor physical performance, functional dependence, and polypharmacy. The number of items with impairment in the K-FRAIL scale was positively associated with the frailty index (B = 3.73, p < 0.001). The K-FRAIL scale could differentiate vulnerability from robustness with a sensitivity of 0.90 and a specificity of 0.33. Of all patients, 75 (72.8%) completed the K-FRAIL scale within < 3 minutes. Conclusions: The K-FRAIL scale is correlated with the frailty index and is a simple tool to screen for frailty in a clinical setting.

A New Equation to Estimate Muscle Mass from Creatinine and Cystatin C

Background With evaluation for physical performance, measuring muscle mass is an important step in detecting sarcopenia. However, there are no methods to estimate muscle mass from blood sampling. Methods To develop a new equation to estimate total-body muscle mass with serum creatinine and cystatin C level, we designed a cross-sectional study with separate derivation and validation cohorts. Total body muscle mass and fat mass were measured using dual-energy x-ray absorptiometry (DXA) in 214 adults aged 25 to 84 years who underwent physical checkups from 2010 to 2013 in a single tertiary hospital. Serum creatinine and cystatin C levels were also examined. Results Serum creatinine was correlated with muscle mass (P < .001), and serum cystatin C was correlated with body fat mass (P < .001) after adjusting glomerular filtration rate (GFR). After eliminating GFR, an equation to estimate total-body muscle mass was generated and coefficients were calculated in the derivation cohort. There was an agreement between muscle mass calculated by the novel equation and measured by DXA in both the derivation and validation cohort (P < .001, adjusted R2 = 0.829, β = 0.95, P < .001, adjusted R2 = 0.856, β = 1.03, respectively). Conclusion The new equation based on serum creatinine and cystatin C levels can be used to estimate total-body muscle mass.

Prediction of Mortality and Postoperative Complications using the Hip-Multidimensional Frailty Score in Elderly Patients with Hip Fracture

High mortality and dependent living after hip fracture pose a significant public health concern. Retrospective study was conducted with 481 hip fracture patients (≥65 years of age) undergoing surgery from March 2009 to May 2014. The Hip-MFS was calculated by Comprehensive Geriatric Assessment (CGA). The primary outcome was the 6-month all-cause mortality rate. The secondary outcomes were 1-year all-cause mortality, postoperative complications and prolonged hospital stay, and institutionalization. Thirty-five patients (7.3%) died within 6 months after surgery (median [interquartile range], 2.9 [1.4–3.9] months). The fully adjusted hazard ratio per 1 point increase in Hip-MFS was 1.458 (95% confidence interval [CI]: 1.210–1.758) for 6-months mortality and odds ratio were 1.239 (95% CI: 1.115–1.377), 1.156 (95% CI: 1.031–1.296) for postoperative complications and prolonged total hospital stay, respectively. High-risk patients (Hip-MFS > 8) showed higher risk of 6-month mortality (hazard ratio: 3.545, 95% CI: 1.466–8.572) than low-risk patients after adjustment. Hip-MFS successfully predict 6-month mortality, postoperative complications and prolonged hospital stay in elderly hip fracture patients after surgery. Hip-MFS more precisely predict 6-month mortality than age or existing tools (P values of comparison of ROC curve: 0.002, 0.004, and 0.044 for the ASA classification, age and NHFS, respectively).

Deflection routing in 3D Network-on-Chip with TSV serialization

This paper proposes a deflection routing for 3D NoC with serialized TSVs. Bufferless deflection routing provides area- and power-efficient communication under low to medium traffic load. Under 3D circumstances, the bufferless deflection routing can yield even better performance than buffered routing when key aspects are properly taken into account. Evaluation of the proposed scheme shows its effectiveness in throughput, latency, and energy consumption.

The measurement of bone mineral density of bilateral proximal humeri using DXA in patients with unilateral rotator cuff tear

SummaryWe propose that the measurement of the bone mineral density (BMD) of the proximal humerus be standardized using the dual energy X-ray absorptiometry (DXA) in patients supposed to undergo rotator cuff repair surgery as well as those with the fracture of the proximal humerus as the BMD of the proximal humerus is decreased in these patients.IntroductionWe propose that the measurement of the BMD of the proximal humerus be standardized using the DXA in patients who are supposed to undergo rotator cuff repair surgery as well as those with the fracture of the proximal humerus.MethodsWe conducted the prospective study in 213 patients with unilateral rotator cuff tear but without contralateral shoulder pain or disease. In these patients, we preoperatively measured the BMD of the bilateral proximal humeri with a repeat measurement in 20 patients. We predefined three regions of interest (ROIs) in the proximal humerus with the consideration of the rotator cuff repair surgery as well as proximal humeral fractures.ResultsThe measurement of the BMD of the proximal humerus using the DXA showed excellent reliability (intraclass correlation coefficient > .90). BMD values of all three ROIs in the affected shoulder were significantly lower than those in asymptomatic shoulder (all p < 0.05). In female patients, the BMD values of ROIs in bilateral shoulder were significantly lower than those in male patients (all p < 0.001). In multiple regressions, however, there were no significant correlations between other clinical characteristics, except for the gender, and the BMD of GT in the affected shoulder.ConclusionsIt is imperative that the bone quality of the proximal humerus be accurately evaluated prior to surgery in patients who are supposed to undergo rotator cuff repair using suture anchors as well as in those with proximal humeral fractures. This is because the BMD of the proximal humerus is decreased in these patients.

Deflection routing in 3D network-on-chip with limited vertical bandwidth

This article proposes a deflection routing for 3D NoC with serialized TSVs for vertical links. Compared to buffered routing, deflection routing provides area- and power-efficient communication and little loss of performance under low to medium traffic load. Under 3D environments, the deflection routing can yield even better performance than buffered routing when key aspects are properly taken into account. However, the existing deflection routing technique cannot be directly applied because the serialized TSV links will take longer time to send data than ordinary planar links and cause many problems. A naive deflection through a TSV link can cause significantly longer latency and more energy consumption even for communications through planar links. This article proposes a method to mitigate the effect and also solve arising deadlock and livelock problems. Evaluation of the proposed scheme shows its effectiveness in throughput, latency, and energy consumption.

Association between Frailty and Hypertension Prevalence, Treatment, and Control in the Elderly Korean Population

Frailty is a common geriatric syndrome characterized by increased risk of disability, hospitalization, and mortality. Hypertension (HTN) is one of the most common chronic medical conditions in the elderly. However, there have been few studies regarding the association between frailty and HTN prevalence, treatment, and control rates. We analyzed data of 4,352 older adults (age ≥ 65 years) from the fifth Korea National Health and Nutrition Examination Survey. We constructed a frailty index based on 42 items and classified participants as robust, pre-frail, or frail. Of the subjects, 2,697 (62.0%) had HTN and 926 (21.3%) had pre-HTN. Regarding frailty status, 721 (16.6%), 1,707 (39.2%), and 1,924 (44.2%) individuals were classified as robust, pre-frail and frail, respectively. HTN prevalence was higher in frail elderly (67.8%) than pre-frail (60.8%) or robust elderly (49.2%) (P < 0.001). Among hypertensive patients, frail elderly were more likely to be treated than pre-frail or robust elderly (P < 0.001), but the proportion of patients whose blood pressure was under control ( < 150/90 mmHg) was lower in frail elderly (P = 0.005). Considering the adverse cardiovascular outcomes associated with frailty, more attention should be paid to the blood pressure control of the frail elderly.