The Phenomenon of "Obesity Paradox" in Neck of Femur Fractures

Effects of body mass index on mortality in elderly patients with hip fractures

Hip fractures remain a substantial health concern, particularly among elderly individuals with osteoporosis, leading to high global mortality rates. This study aimed to analyze the association between body mass index (BMI) and postoperative mortality in patients who underwent surgery for hip fractures. A total of 680 patients treated at a single institution between January 2018 and December 2022 were included. Factors such as age, BMI, sex, Charlson Comorbidity Index (CCI), preoperative hemoglobin levels, American Society of Anesthesiologists score, anesthesia method, duration of surgery, and time from injury to surgery were assessed. Underweight status, male sex, higher CCI, and general anesthesia were significantly associated with 1-year and in-hospital mortality. Notably, underweight individuals exhibited a higher risk of mortality than normal-weight individuals, and female patients had lower mortality rates. This study underscores the importance of considering BMI, along with other demographic and clinical factors, in predicting postoperative mortality among patients with hip fractures, aiding the development of tailored management strategies to improve outcomes and reduce complications in this vulnerable patient population.

Risk factors and nomogram predictive model of severe postoperative complications in elderly patients with intertrochanteric fractures

Objective

To analyze risk factors of severe postoperative complications in elderly patients with intertrochanteric fractures (ITF), and to construct a predictive model.

Methods

The medical records of 316 elderly patients with ITF who underwent surgical treatment in Suzhou Hospital of Integrated Traditional Chinese and Western Medicine from January 2020 to December 2022 were retrospectively analyzed. Univariate and multivariate logistic regression analyses were performed to identify risk factors of severe postoperative complications. A nomogram prediction model was constructed using the RMS package of R4.1.2 software. Accuracy and stability of the model was assessed using the receiver operating characteristic (ROC) curve, Hosmer-Lemeshow goodness-of-fit test, and decision curve analysis.

Results

Age, American Society of Anesthesiologists (ASA) grading, combined medical diseases, preoperative bedridden condition, frailty, and preoperative albumin levels were all risk factors for severe postoperative complications in ITF patients were noted. These factors were then used to build a risk prediction model that had an area under the ROC curve (AUC) of 0.899 (95% confidence interval (CI): 0.846-0.951). The internal validation results of the Bootstrap method showed that the C-index value of the model was 0.899, and the calibration curve had a good fit with the ideal curve.

Conclusions

Age, ASA grading, combined medical diseases, preoperative bedridden condition, frailty, and preoperative albumin levels were independent risk factors for severe postoperative complications in elderly ITF patients. The constructed prediction model based on the above risk factors has a high predictive value.

Development of Prediction Model for 1-year Mortality after Hip Fracture Surgery

Purpose

Hip fractures are associated with increased mortality. The identification of risk factors of mortality could improve patient care. The aim of the study was to identify risk factors of mortality after surgery for a hip fracture and construct a mortality model.

Materials and Methods

A cohort study was conducted on patients with hip fractures at two institutions. Five hundred and ninety-seven patients with hip fractures that were treated in the tertiary hospital, and another 147 patients that were treated in a secondary hospital. The perioperative data were collected from medical charts and interviews. Functional Assessment Measure score, Short Form-12 and mortality were recorded at 12 months. Patients and surgery variables that were associated with increased mortality were used to develop a mortality model.

Results

Mortality for the whole cohort was 19.4% at one year. From the variables tested only age >80 years, American Society of Anesthesiologists category, time to surgery (>48 hours), Charlson comorbidity index, sex, use of anti-coagulants, and body mass index <25 kg/m2 were associated with increased mortality and used to construct the mortality model. The area under the curve for the prediction model was 0.814. Functional outcome at one year was similar to preoperative status, even though their level of physical function dropped after the hip surgery and slowly recovered.

Conclusion

The mortality prediction model that was developed in this study calculates the risk of death at one year for patients with hip fractures, is simple, and could detect high risk patients that need special management.

Venous thromboembolism and major adverse cardiovascular events in patients with hip fractures suffering from SARS-CoV-2 infection: a systematic review

INTRODUCTION

Hip fractures represent 1 of the most common injuries in older adults. They are associated with increased perioperative morbidity and mortality. Additionally, current research suggests that SARS-COV-2 infection may worsen the prognosis of the hip fracture patients who undergo hip fixation. The aims of the present study were: (1) to determine the rate of specific adverse events including VTE (venous thromboembolism) and major adverse cardiovascular events (MACEs) in patients with hip fracture and concomitant SARS-CoV-2 infection undergoing surgery; and (2) to examine if the aforementioned population is at increased risk for VTE and MACEs, when compared to SARS-CoV-2 free patients with hip fracture.

METHODS

PubMed, EMBASE, Cochrane, Web of Science, Google scholar and medRxiv were searched from March 2020 to January 2021 for English language studies with patients suffering from hip fractures and SARS-COV-2 -CoV-2. 2 researchers were involved in the data extraction and the quality assessment of the studies respectively.

RESULTS

The literature search yielded a total of 1256 articles of which 14 were included in the systematic review and 7 in the meta-analysis respectively. The estimated pooled rate for VTE and MACE were 4.3% and 6.3% respectively. Patients with hip fracture and concomitant SARS-CoV-2 infection who undergo surgery are at increased risk for VTE, when compared to SARS-CoV-2 free patients (odds ratio 2.8 [95% CI, 1.1-7.1]). These patients are also at increased risk for MACE postoperatively as indicated by the odds ratio 2.4 (95% CI, 1.0-5.8). The quality of the studies was moderate.

CONCLUSIONS

Although there is a lack of high-quality data it seems that patients with hip fractures and concomitant SARS-CoV-2 infection are facing a 2.8 and 2.4 times increased risk for VTE and MACE.

Associations between body mass index and all-cause mortality: A systematic review and meta-analysis

Fasting insulin and c-reactive protein confound the association between mortality and body mass index. An increase in fat mass may mediate the associations between hyperinsulinemia, hyperinflammation, and mortality. The objective of this study was to describe the "average" associations between body mass index and the risk of mortality and to explore how adjusting for fasting insulin and markers of inflammation might modify the association of BMI with mortality. MEDLINE and EMBASE were searched for studies published in 2020. Studies with adult participants where BMI and vital status was assessed were included. BMI was required to be categorized into groups or parametrized as non-first order polynomials or splines. All-cause mortality was regressed against mean BMI squared within seven broad clinical populations. Study was modeled as a random intercept. β coefficients and 95% confidence intervals are reported along with estimates of mortality risk by BMIs of 20, 30, and 40 kg/m2 . Bubble plots with regression lines are drawn, showing the associations between mortality and BMI. Splines results were summarized. There were 154 included studies with 6,685,979 participants. Only five (3.2%) studies adjusted for a marker of inflammation, and no studies adjusted for fasting insulin. There were significant associations between higher BMIs and lower mortality risk in cardiovascular (unadjusted β -0.829 [95% CI -1.313, -0.345] and adjusted β -0.746 [95% CI -1.471, -0.021]), Covid-19 (unadjusted β -0.333 [95% CI -0.650, -0.015]), critically ill (adjusted β -0.550 [95% CI -1.091, -0.010]), and surgical (unadjusted β -0.415 [95% CI -0.824, -0.006]) populations. The associations for general, cancer, and non-communicable disease populations were not significant. Heterogeneity was very large (I2  ≥ 97%). The role of obesity as a driver of excess mortality should be critically re-examined, in parallel with increased efforts to determine the harms of hyperinsulinemia and chronic inflammation.

The Impact of Metabolic Syndrome and Obesity on Perioperative Total Joint Arthroplasty Outcomes: The Obesity Paradox and Risk Assessment in Total Joint Arthroplasty

Background

The relationship between elevated body mass index (BMI) and adverse outcomes in joint arthroplasty is well established in the literature. This paper aims to challenge the conventional thought of excluding patients from a total knee or hip replacement based on BMI alone. Instead, we propose using the metabolic syndrome (MetS) and its defining components to better identify patients at high risk for intraoperative and postoperative complications.

Methods

Patients who underwent primary, elective total knee and total hip arthroplasty were identified in the 2015-2020 American College of Surgeons National Surgical Quality Improvement Program database. Several defining components of MetS, such as hypertension, diabetes, and obesity, were compared to a metabolically healthy cohort. Postoperative outcomes assessed included mortality, length of hospital stay, 30-day surgical and medical complications, and discharge.

Results

The outcomes of 529,737 patients from the American College of Surgeons National Surgical Quality Improvement Program who underwent total knee and total hip arthroplasty were assessed. MetS is associated with increased complications and increased mortality. Both hypertension and diabetes are associated with increased complications but have no impact on mortality. Interestingly, while obesity was associated with increased complications, there was a significant decrease in mortality.

Conclusions

Our results show that the impact of MetS is more than the sum of its constitutive parts. Additionally, obese patients experience a protective effect, with lower mortality than their nonobese counterparts. This study supports moving away from strict BMI cutoffs alone for someone to be eligible for an arthroplasty surgery and offers more granular data for risk stratification and patient selection.

Obese elderly patients with hip fractures may have better survival outcomes after surgery

BACKGROUND

In recent years, there has been an increasing amount of research on the "obesity paradox". So our primary objective was to explore whether this phenomenon exists in our study, and secondary objective was to determine the effect of body mass index (BMI) on major complications, and the incidence of acute kidney injury (AKI) after hip fracture surgery after controlling for confounding factors.

METHODS

We included patients over 70 years old with hip fracture who were admitted to the Department of Orthopedics, Peking University First Hospital between 2015 and 2021. Patients were classified as underweight (UW, < 18.5 kg/m²), normal weight (NW, 18.5-24.9 kg/m²), overweight (OW, 25.0-29.9 kg/m²) and obese (OB, ≥ 30.0 kg/m²). We analyzed demographic characteristics, operation information and postoperative outcomes. Using multivariate regression with normal-weight patients as the reference, we determined the odds of 1-year mortality, major complications, and AKI by BMI category.

RESULTS

A total of 644 patients were included. Nine percent of patients died after 1 year, 18% had major postoperative complications, and 12% had AKI. There was a U-shaped relationship between BMI and the rates of major complications or AKI. However, there was a linear decreasing relationship between 1-year mortality and BMI. After controlling for confounding factors, multivariate regression analysis showed that the risk of 1-year mortality after surgery was 2.24 times higher in underweight patients than in normal-weight patients (P < 0.05, OR: 2.24, 95% CI 1.14-4.42). Compared with normal-weight patients, underweight patients had a 2.07 times increased risk of major complications (P < 0.05, OR 2.07, 95% CI 1.21-3.55), and the risk of major complications in obese patients was 2.57 times higher than that in normal-weight patients (P < 0.05, OR 2.57, 95% CI 1.09-6.09). Compared with normal-weight, underweight patients had a 2.18 times increased risk of AKI (P < 0.05, OR 2.18, 95% CI 1.17-4.05).

CONCLUSIONS

The 1-year mortality risk of patients with higher BMI was significantly reduced. Besides, compared with normal-weight patients, underweight patients and obese patients have a higher risk of major complications; low-weight and obese patients are at higher risk for AKI.

Attendance Improves Student Electrocardiography Interpretation Skills Using the Flipped Classroom Format

The implementation of classroom capture and casting technologies has changed how content can be accessed. Students can access live, streaming, and/or recorded formats of material. Broadening this accessibility has, in turn, introduced flexibility for both the learner and the instructor. This flexibility has impacted the necessity of attendance to access classroom-delivered content. There are many reports that investigate the changing attendance climate as well as the potential impact of attendance on student outcomes. Here we investigated the impact of attending classroom activities on student performance with two common content delivery methods in an undergraduate, pre-clinical cardiology course. Electrocardiography (ECG) interpretation was taught using a flipped classroom format which allowed for the practice of interpretive skills with faculty guidance. Other components of the course related to the diagnosis, treatment, and management of cardiovascular disease were delivered using a lecture-based format. The results demonstrate that attendees outperform their classmates in the ability to interpret ECGs and related content. However, the attending student does not appear to have a performance advantage when content is delivered by lecture. The results provide evidence for students to prioritize their time when making decisions about attendance, based on teaching modality, when given a choice. Further, the information can guide curricular change and help colleges and programs identify curricular activities that have a clear attendance benefit for students.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40670-022-01689-5.

The impact of body mass index on mortality rates of hip fracture patients: a systematic review and meta-analysis

Obesity has been recognized as a global epidemic as approximately one-third of the world's population. Findings on early and late mortality rates between obese, overweight, and underweight vs normal body mass index (BMI) patients confirm that the obese and overweight patients were found to have lower risk and underweight patients were found to have increased risk of mortality as compared to normal weighted patients. It is unclear if the "obesity paradox" exists with survival outcomes of hip fracture patients. We hereby reviewed early (in-hospital and 30-day mortality) and late mortality (≥ 1-year) rates between obese, overweight, and underweight vs normal body mass index (BMI) patients with hip fractures. PubMed, Embase, ScienceDirect, CENTRAL, and Google Scholar were searched for studies reporting mortality rates of hip fracture patients based on BMI. We pooled crude and adjusted mortality rates in a random-effects model. Eleven studies were included. Meta-analysis indicated significantly reduced risk of early (RR: 0.64 95% CI: 0.59, 0.69 I² = 0% p < 0.00001) and late mortality rates (RR: 0.78 95% CI: 0.67, 0.91 I² = 93% p = 0.002) in obese vs normal BMI patients. Meta-analysis failed to demonstrate any statistically significant difference in early mortality (RR: 0.90 95% CI: 0.54, 1.53 I² = 44% p = 0.71) but significantly reduced risk of late mortality in overweight vs normal BMI patients (RR: 0.85 95% CI: 0.73, 0.93 I² = 84% p = 0.003). Scarce data suggested increased risk of early (RR: 1.44 95% CI: 1.08, 1.93 I² = 26% p = 0.01) and late mortality (RR: 1.23 95% CI: 1.08, 1.41 I² = 7% p = 0.002) in underweight vs normal BMI patients. Adjusted data corroborated the reduced risk of mortality in overweight (HR: 0.78 95% CI: 0.74, 0.83 I² = 0% p < 0.0001) and obese patients (HR: 0.66 95% CI: 0.60, 0.73 I² = 0% p < 0.0001). Our results indicate that the "obesity paradox" exists with survival outcomes of hip fracture patients. Obese and overweight patients were found to have lower risk and underweight patients were found to have increased risk of mortality as compared to normal weighted patients.

Inverse relation of body weight with short-term and long-term mortality following hip fracture surgery: a meta-analysis

Background

The obesity paradox, which suggests that high body weight is positively associated with survival in some diseases, has not been proven in patients with hip fracture. In this study, meta-analysis of previous studies on the impacts of body weight on postoperative mortality following hip fracture surgery in older adults was conducted.

Methods

PubMed, Embase, and Cochrane library were searched for studies investigating the correlation between mortality after hip fracture surgery and body weight. The search main items included: (“Body mass index” OR “BMI” or “body weight”) and (“hip fracture” or “hip fractures”). Studies contained data on short-term (≤ 30-day) and long-term (≥ 1 year) mortality after hip fracture and its association with distinct body weight or BMI groups were reported as full-text articles were included in this meta-analysis.

Results

Eleven separate studies were included. The definitions of underweight and obesity differed among the included studies, but the majority of the enrolled studies used the average body weight definition of a BMI of 18.5 to 24.9 kg/m²; underweight referred to a BMI of < 18.5 kg/m²; and obesity pertained to a BMI of > 30 kg/m². Based on the generalized definitions of body-weight groups from the enrolled studies, the group with obesity had lower long-term (odds ratio [OR]: 0.63, 95% CI: 0.50–0.79, P < 0.00001) and short-term (OR: 0.63, 95% CI: 0.58–0.68, P ≤ 0.00001) mortality rates after hip fracture surgery when compared with patients with average-weight group. However, compared with the average-weight group, the underweight group had higher long-term (OR: 1.51, 95% CI: 1.15-1.98, P=0.003) and short-term (OR: 1.49, 95% CI: 1.29-1.72, P<0.00001) mortality rates after hip fracture surgery.

Conclusions

Current evidence demonstrates an inverse relation of body weight with long-term and short-term mortality after hip fracture surgery in older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03131-3.

Obesity paradox in joint replacement for osteoarthritis - truth or paradox?

Obesity is associated with an increased risk of cardiovascular disease (CVD) and other adverse health outcomes. In patients with pre-existing heart failure or coronary heart disease, obese individuals have a more favourable prognosis compared to individuals who are of normal weight. This paradoxical relationship between obesity and CVD has been termed the 'obesity paradox'. This phenomenon has also been observed in patients with other cardiovascular conditions and diseases of the respiratory and renal systems. Taking into consideration the well-established relationship between osteoarthritis (OA) and CVD, emerging evidence shows that overweight and obese individuals undergoing total hip or knee replacement for OA have lower mortality risk compared with normal weight individuals, suggesting an obesity paradox. Factors proposed to explain the obesity paradox include the role of cardiorespiratory fitness ("fat but fit"), the increased amount of lean mass in obese people, additional adipose tissue serving as a metabolic reserve, biases such as reverse causation and confounding by smoking, and the co-existence of older age and specific comorbidities such as CVD. A wealth of evidence suggests that higher levels of fitness are accompanied by prolonged life expectancy across all levels of adiposity and that the increased mortality risk attributed to obesity can be attenuated with increased fitness. For patients about to have joint replacement, improving fitness levels through physical activities or exercises that are attractive and feasible, should be a priority if intentional weight loss is unlikely to be achieved.

The Effects of Obesity on Mortality Following Coronary Artery Bypass Graft Surgery: A Retrospective Study from a Single Center in China

Background

Coronary artery bypass graft (CABG) surgery has become a routine surgical procedure for patients with occlusive coronary artery atherosclerosis. Worldwide, increasing levels of obesity are associated with ischemic heart disease and systemic comorbidities. This retrospective study from a single center in China aimed to investigate the effects of obesity on patient mortality following CABG surgery.

Material/Methods

Patients undergoing CABG (N=1471) were grouped according to body mass index (BMI) as normal weight (N=596), overweight (N=684), or obese (N=191). Baseline clinical characteristics and outcomes were recorded. Logistic regression analysis was performed for 30-day postoperative mortality. Kaplan-Meier survival curves were plotted, and Cox regression analysis investigated risk and protective factors for long-term mortality, with subgroup analysis for differences between on-pump and off-pump CABG groups.

Results

The 30-day postoperative mortality was 5.0% in the normal-weight group, 1.3% in the overweight group, and 0% in the obese group. BMI was an independent protective factor for 30-day postoperative mortality (odds ratio=0.748; 95% confidence interval, 0.640–0.874; P<0.001). The 10-year mortality for the groups was 13.2% (normal), 7.8% (overweight), and 12.7% (obese). The >20-year mortality rates for the groups were 33.0% (normal), 41.5% (overweight), and 12.7% (obese). There was no significant correlation between BMI and long-term mortality. Being overweight had a protective effect against long-term mortality in the off-pump CABG subgroup.

Conclusions

An “obesity paradox” was identified in postoperative outcomes in patients following CABG surgery, with an increased BMI associated with reduced 30-day postoperative mortality. This association was more significant in the off-pump CABG group.