Low serum calcium is associated with perioperative blood loss and transfusion rate in elderly patients with hip fracture: a retrospective study

Development and validation of machine learning models to predict perioperative transfusion risk for hip fractures in the elderly

BACKGROUND

Patients with hip fractures frequently need to receive perioperative transfusions of concentrated red blood cells due to preoperative anemia or surgical blood loss. However, the use of perioperative blood products increases the risk of adverse events, and the shortage of blood products is prompting us to minimize blood transfusion. Our study aimed to construct a machine learning algorithm predictive model to identify patients at high risk for perioperative transfusion early in hospital admission and to manage their patient blood to reduce transfusion requirements.

METHODS

This study collected patients hospitalized for hip fractures at a university hospital from May 2016 to November 2022. All patients included in the analysis were randomly divided into a training set and validation set according to 70:30. Eight machine learning algorithms, CART, GBM, KNN, LR, NNet, RF, SVM, and XGBoost, were used to construct the prediction models. The models were evaluated for discrimination, calibration, and clinical utility, and the best prediction model was selected.

RESULTS

A total of 805 patients were included in the study, of whom 306 received transfusions during the perioperative period. We screened eight features used to construct the prediction model: age, fracture time, fracture type, hemoglobin, albumin, creatinine, calcium ion, and activated partial thromboplastin time. After evaluating and comparing the performance of each of the eight models, the model constructed by the XGBoost algorithm had the best performance, with MCC values of 0.828 and 0.939 in the training and validation sets, respectively. In addition, it had good calibration and clinical utility in both the training and validation sets.

CONCLUSION

The model constructed by the XGBoost algorithm has the best performance, using this model to identify patients at high risk for transfusion early in their admission and promptly incorporating them into a patient blood management plan can help reduce the risk of transfusion.

The Relationship Between Ionized Calcium Levels and Prognosis in Patients with Spontaneous Subarachnoid Hemorrhage

BACKGROUND

The serum calcium plays a role as a cofactor in critical steps such as cardiac contractility, vascular tone, and the coagulation cascade. This study aimed to determine if the level of ionized calcium can predict outcomes in patients with spontaneous subarachnoid hemorrhage (SAH) in the emergency department.

METHODS

The study was a retrospective cross-sectional case series. Patients aged 18 and over diagnosed with spontaneous SAH in the emergency department were included in the study. Patients' demographic characteristics, comorbidities, vital signs, laboratory parameters, World Federation of Neurosurgical Societies score, SAH grading according to the Fisher scale, needs of mechanical ventilation and inotropic treatment, administered treatments, complications, Rankin scores at discharge, and outcome were recorded in a standard data form.

RESULTS

A total of 267 patients were studied, with a mean age of 55.5 ± 13.4 years, and 53.9% (n = 144) were female. Hydrocephalus was present in 16.5% of patients. The average hospital stay was 20.4 ± 19.8 days. Mortality rate was 34.8% (n = 93). Mortality was significantly higher in patients with low calcium levels upon admission (P = 0.024). Ionized calcium levels during complication development independently predicted mortality (OR: 0.945, 95% CI: 0.898-0.996, P = 0.034). Patients with poor neurologic outcomes (Rankin: 3-6) had significantly lower initial ionized calcium levels (P = 0.002).

CONCLUSIONS

The ionized calcium level is a readily accessible blood gas parameter that assists clinicians in predicting functional independence and mortality at discharge in patients presenting to the emergency department with spontaneous SAH.

The multi-faceted nature of age-associated osteoporosis

Age-associated osteoporosis (AAOP) poses a significant health burden, characterized by increased fracture risk due to declining bone mass and strength. Effective prevention and early treatment strategies are crucial to mitigate the disease burden and the associated healthcare costs. Current therapeutic approaches effectively target the individual contributing factors to AAOP. Nonetheless, the management of AAOP is complicated by the multitude of variables that affect its development. Main intrinsic and extrinsic factors contributing to AAOP risk are reviewed here, including mechanical unloading, nutrient deficiency, hormonal disbalance, disrupted metabolism, cognitive decline, inflammation and circadian disruption. Furthermore, it is discussed how these can be targeted for prevention and treatment. Although valuable as individual targets for intervention, the interconnectedness of these risk factors result in a unique etiology for every patient. Acknowledgement of the multifaceted nature of AAOP will enable the development of more effective and sustainable management strategies, based on a holistic, patient-centered approach.

Early surgery within 48 h was associated with reduced perioperative blood loss and red blood cell transfusion requirements in older patients with hip fracture: a retrospective study

PURPOSE

The aim of this study was to analyze the relationship between the timing of surgery and perioperative blood loss, red blood cell (RBC) transfusion rate, and RBC transfusion volume in older patients with hip fracture.

METHODS

From January 2020 to August 2022, this retrospective study enrolled older patients with hip fracture who underwent surgery in our hospital. The demographics, fracture type, type of surgery, time from injury to hospital, timing of surgery, medical history (hypertension, diabetes), duration of surgery, intraoperative blood loss, laboratory tests, and preoperative, postoperative and perioperative RBC transfusion requirements were recorded and analyzed. According to the surgical treatment within 48 h or after 48 h after admission, the patients were divided into early surgery group (ES) and delayed surgery group (DS).

RESULTS

A total of 243 older patients with hip fracture were finally included in the study. Among these, 96 patients (39.51%) underwent surgery within 48 h of admission and 147 (60.49%) underwent surgery after this time. Total blood loss (TBL) in the ES group was lower than that in the DS group (576.03 ± 265.57 ml vs 699.26 ± 380.58 ml, P = 0.003). Preoperative RBC transfusion rate, and preoperative and perioperative RBC transfusion volume in the ES group were significantly lower than those in the DS group (15.63% vs 26.53%, P = 0.046; 50.00 ± 128.15 ml vs 117.01 ± 225.85 ml, P = 0.004; 80.21 ± 196.63 ml vs 144.90 ± 253.52 ml, P = 0.027).

CONCLUSION

Timing of surgery within 48 h of admission for older patients with hip fracture was associated with reduced the total blood loss and RBC transfusion requirements during the perioperative period.

The Magnesium Status and Suggested Reference Ranges of Plasma Magnesium, Calcium, and Calcium/Magnesium Ratio in Chinese Adults over 45 Years Old

Magnesium (Mg) is an essential nutrient that participates in various enzymatic reactions and regulates important biological functions. The distribution and reference ranges in China have not been reported in populations more than 45 years old. This study aimed to assess the magnesium status and determine the reference values of plasma Mg, Ca, and Ca/Mg ratios for China's population more than 45 years old. A total of 2101 people were randomly selected from the China Nutrition and Health surveillance (CNHS) (2015-2017), considering the regional types and monitoring points. Then, 337 healthy individuals were further selected by a series of strict inclusion criteria to explore the reference range. The plasma magnesium and calcium were tested by inductively coupled plasma mass spectrometry (ICP-MS). The suggested reference values for plasma Mg, Ca, and Ca/Mg ratios were 0.75-1.14 mmol/L, 2.17-3.64 mmol/L, and 2.36-3.66, respectively. Taking 0.75 mmol/L as the lower cut-off limit, the prevalence of Mg deficiency was 6.66%, and the average level of plasma magnesium was 0.88 mmol/L for populations older than 45 years in China. In conclusion, this study provides the magnesium status and reference ranges for plasma Mg, Ca, and Ca/Mg ratio for Chinese people over 45 years old. The results of the recommended reference ranges in this study were very similar to our published results in women of reproductive age. Thus, the reference range of plasma magnesium in different populations in China was further improved.

A New Nomogram Model for Predicting 1-Year All-Cause Mortality After Hip Arthroplasty in Nonagenarians With Hip Fractures: A 20-Year Period Retrospective Cohort Study

Background

China has become an ageing society and as it continues to age, it will face an increasing number of hip fractures in nonagenarians. However, few preoperative assessment tools to determine the postoperative mortality risk in nonagenarians with hip fracture were available. The aim of this study was to identify all-cause mortality risk factors after hip arthroplasty in nonagenarians with hip fractures and to establish a new nomogram model to optimize the individualized hip arthroplasty in nonagenarians with hip fractures.

Methods

We retrospectively studied 246 consecutive nonagenarians diagnosed with hip fracture from August 2002 to February 2021 at our center. During the follow-up, 203 nonagenarians with a median age of 91.9 years treated with hip arthroplasty were included, of which 136 were females and 67 were males, and 43 nonagenarians were excluded (40 underwent internal fixation and 3 were lost to follow-up). The full cohort was randomly divided into training (50%) and validation (50%) sets. The potential predictive factors for 1-year all-cause mortality after hip arthroplasty were assessed by univariate and multivariate COX proportional hazards regression on the training set, and then, a new nomogram model was established and evaluated by concordance index (C-index) and calibration curves.

Results

After analyzing 44 perioperative variables including demographic characteristics, vital signs, surgical data, laboratory tests, we identified that age-adjusted Charlson Comorbidity Index (aCCI) (p = 0.042), American Society of Anesthesiologists (ASA) classification (p = 0.007), Urea (p = 0.028), serum Ca2+ (p = 0.011), postoperative hemoglobin (p = 0.024) were significant predictors for 1-year all-cause mortality after hip arthroplasty in the training set. The nomogram showed a robust discrimination, with a C-index of 0.71 (95%CIs, 0.68–0.78). The calibration curves for 1-year all-cause mortality showed optimal agreement between the probability as predicted by the nomogram and the actual probability in training and validation sets.

Conclusion

A novel nomogram model integrating 5 independent predictive variables were established and validated. It can effectively predict 1-year all-cause mortality after hip arthroplasty in nonagenarians with hip fracture and lead to a more optimized and rational therapeutic choice.

Low Mean Platelet Volume is Associated with Deep Vein Thrombosis in Older Patients with Hip Fracture

This study aimed to explore the association between mean platelet volume (MPV) and preoperative deep vein thrombosis (DVT) in older patients with hip fracture. A total of 352 consecutive older patients with hip fracture were included from January 2014 to December 2020. MPV values were measured on admission, and color Doppler ultrasonography was performed for DVT screening before the planned surgery. The receiver operating characteristic (ROC) curve was used to establish the optimal cut-off value for the prediction of DVT. Univariate and multivariate logistic regression analysis were used to examine the association between factors and DVT. The overall prevalence of preoperative DVT was 15.1%, and patients with DVT had a lower value of MPV than non-DVT patients (11.6 ± 1.2 fL vs 12.3 ± 1.4 fL, P < .01). The cut-off point according to the ROC curve for MPV was 13.3 fL, and multivariate logistic regression analysis showed that MPV level < 13.3 fL was significantly associated with an increased risk of DVT (OR = 4.857, 95% CI: 1.091-21.617, P = .038), and with every 1.0 fL decrease in MPV, the risk increased by 27.7% (OR = 1.277, 95% CI: 1.001-1.629, P = .047). Our findings indicate that a low MPV level is associated with DVT in older patients with hip fracture. As MPV is a simple indicator that can be calculated from the blood routine test, it may be a potential biomarker of DVT with the combination of other tests, further studies are needed to confirm these results.