Accuracy of the WHO's body mass index cut-off points to measure gender- and age-specific obesity in middle-aged adults living in the city of Rio de Janeiro, Brazil

Urinary polycyclic aromatic hydrocarbons and adult obesity among the US population: NHANES 2003-2016

Polycyclic aromatic hydrocarbons (PAHs) are naturally occurring environmental pollutants that may contribute to obesity in the adult population. To investigate the relationship between the urinary concentrations of PAH metabolites and adult obesity among the US population, the National Health and Nutritional Examination Survey (NHANES, 2003-2016) was used as a data source for this study. As many as 4464 participants in the NHANES 2003-2016 were included in the final analyses. We used logistic regression to look at the link between urinary PAH metabolites and obesity, using odds ratios (ORs) and 95% confidence intervals (CIs). The study sample comprised 4464 individuals aged ≥18 years, 2199 were male and 2265 were female. The study characteristics for four different quartiles were analyzed, and the average ages of the four urinary PAH quartiles were 49.61 ± 20.01, 46.63 ± 20.33, 44.28 ± 19.19, and 43.27 ± 17.68 years, respectively. In the quartile analysis of all participants, the third quartile was significantly associated with an increased prevalence of obesity (OR = 1.33, 95% CI = 1.12-1.59) with p-values <.05. In addition, females, but not males, had a strong link between the second, third, and fourth quartiles of urinary PAH and a higher risk of obesity (OR = 1.27, 95% CI = 1.00-1.61; OR = 1.52, 95% CI = 1.19-1.94; and OR = 1.39, 95% CI = 1.09-1.78). In conclusion, the study observed that urinary PAH metabolites were associated with the prevalence of obesity among the US population.

Normal-Weight Obesity and Metabolic Syndrome in Korean Adults: A Population-Based Cross-Sectional Study

BACKGROUND

The disadvantage of using body mass index (BMI) as an obesity diagnostic tool is that it cannot distinguish between fat mass and lean mass, which may understate the impact of obesity on metabolic complications. This population-based cross-sectional study aimed to investigate the relationship between normal-weight obesity (NWO) and metabolic syndrome in Korean adults aged 20 years (5962 males and 6558 females) who took part in the Korea National Health and Nutrition Examination Surveys from 2008 to 2011.

METHODS

NWO was defined as having a BMI of 18.5 to 24.9 kg/m2 and a body fat percentage of 26.0% in males or 36.0% in females. Metabolic syndrome (MetS) was defined using the revised National Cholesterol Education Program definition, with a Korean-specific waist circumference threshold of >90 cm for males and >85 cm for females.

RESULTS

NWO males and females were 2.7 times (p < 0.001) and 1.9 times (p < 0.001) more likely to develop metabolic syndrome than normal-weight non-obese males and females, respectively. Additionally, NWO females were 1.3 times (p = 0.027) more likely to develop MetS even after adjustments for all measured covariates.

CONCLUSIONS

The current findings of the study show that NWO is a proxy biomarker of MetS to be considered for early intervention.

Adherence to the Mediterranean Diet Is Associated with Health-Related Quality of Life and Anthropometric Measurements in University Professors

The main objective of this study was to assess the relationship between Mediterranean diet (MD) adherence and health-related quality of life (HRQOL) according to the anthropometric measurements of teaching and research staff (TRS) at the University of Granada (UGR), Spain. This diagnostic, non-experimental, cross-sectional, and observational study was performed on university lecturers (65 women and 62 men) using a correlational descriptive methodology. The lecturers' anthropometric measurements were taken, while MD adherence was determined using the PREvention with MEDiterranean diet (PREDIMED) questionnaire. The Short Form Health Survey (SF-36) was used for measuring HRQOL. Better results for body composition were associated with improvements in the physical and mental dimensions and MD adherence. Statistically significant differences were found between sexes, with men showing higher values for weight, height, waist circumference, BMI, waist/hip ratio (WHR), muscle mass, and systolic and diastolic pressure than women. Similarly, MD adherence was positively correlated with vitality (r = 0.233; p = 0.009), social functioning (r = 0.229; p = 0.008), and the mental component summary (r = 0.205; p = 0.021). The regression model determined that the mental component summary (β = 0.239, p = 0.041), diastolic pressure (PD) (β = -0.473, p < 0.000), fat percentage (FP) (β = -0.241, p = 0.004), and age (β = -0.231, p = 0.022) significantly predicted MD adherence. The results obtained in this study suggest that healthy dietary patterns such as the MD and an optimum body composition contribute to an improved HRQOL.

New BMI Cut-Off Points for Obesity in Middle-Aged and Older Adults in Clinical Nutrition Settings in Italy: A Cross-Sectional Study

Obesity is a major health problem defined as an excess accumulation of body fat (BF). The World Health Organization (WHO) usually relies on a body mass index (BMI) ≥ 30 kg/m2 as an indicator of obesity. Due to changes in body composition that occur across the lifespan, with an increase in BF and a decrease in lean mass, we aimed to test the validity of this BMI cut-off point for adiposity in middle-aged and older adults. This cross-sectional study, composed of 4800 adults of mixed gender aged between 40 and 80 years, included (according to the WHO BMI classification) 1087 normal-weight, 1826 overweight, and 1887 obese individuals who were referred to the Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Italy. The sample was then categorized by adiposity status based on the total BF% as measured by dual-energy X-ray absorptiometry (DXA), and the best sensitivity and specificity were attained for predicting obesity according to the receiver operating characteristic curve (ROC) analysis. In a real-world clinical setting, a new BMI cut-off point (BMI = 27.27 kg/m2) has been identified for predicting obesity in middle-aged and older adults. Obesity guidelines in Italy therefore need to be revised accordingly.

Metabolic Obesity in People with Normal Body Weight (MONW)-Review of Diagnostic Criteria

Disorders of metabolic obesity with normal body weight (MONW) are widely recognized risk factors for the development of cardiovascular diseases and type 2 diabetes. Despite this, MONW is not diagnosed in clinical practice. There is no consensus on the definition of MONW, and measuring the degree of insulin resistance or obesity among apparently healthy, non-obese patients is not widely applicable. The awareness of the relationship between metabolic disorders such as MONW and a higher risk of mortality from cardiovascular causes and other related diseases prompts the need for action to be taken aimed at creating appropriate diagnostic models that will allow for the effective detection of those with metabolic abnormalities among people with normal body weight. Such actions are decisive in the prevention and treatment of diseases. Therefore, the purpose of this article is to review the MONW diagnostic criteria used over the years.

Obesity Paradox of All-Cause Mortality in 4,133 Patients Treated with Coronary Revascularization

Objectives

The purpose of this study was to determine whether there is a dose-response relationship between body mass index (BMI) and all-cause mortality in patients after coronary revascularization.

Methods

The MIMIC-III database (version 1.4) was used as the sample population. For variables with less than 10% of values missing, we used the mice package of R software for multiple imputations. Cox regression was used to determine the risk factors of all-cause mortality in patients. RCSs were used to observe the relationship between BMI and all-cause mortality. Additional subgroup and sensitivity analyses were also performed to explore whether the conclusion can be applied to specific groups.

Results

Both univariate and multivariate Cox models indicated that the mortality risk was lower for overweight patients than for normal-weight patients (P < 0.05). In RCS models, BMI had a U-shaped relationship with all-cause mortality of patients after coronary artery bypass grafting (CABG) (P for nonlinearity = 0.0028). There was a weak U-shaped relationship between BMI and all-cause mortality after percutaneous coronary intervention (PCI), but the nonlinear relationship between these two parameters was not significant (P for nonlinearity = 0.1756).

Conclusions

The obesity paradox does exist in patients treated with CABG and PCI. RCS analysis indicated that there was a U-shaped relationship between BMI and all-cause mortality in patients after CABG. After sex stratification, the relationship between BMI and all-cause mortality in male patients who received PCI was L-shaped, while the nonlinear relationship among females was not significant.

MicroRNA Expression Profiles in the Subcutaneous Adipose Tissues of Morbidly Obese Chinese Women

INTRODUCTION

Obesity is a main global health issue and an outstanding cause of morbidity and mortality. Exploring miRNA profiling may help further studies on obesity.

METHODS

Three morbidly obese and 5 normal-weight Chinese women were enrolled in the microarray testing group. Abdominal subcutaneous adipose tissue (SAT) samples were excised. Total RNAs including miRNAs were extracted. Affymetrix GeneChip miRNA 4.0 Array was used to compare the expression profiles of miRNAs between the 2 groups. Two algorithms, miRanda and TargetScan, were used to predict target messenger RNAs (mRNAs). Bioinformatics analysis was then done based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The sample sizes were further expanded to 8 morbidly obese and 9 normal-weight subjects, and quantitative real-time PCR (qRT-PCR) was utilized to verify the expression of differential miRNAs and target genes.

RESULTS

As per the microarray assay, 58 miRNAs were differentially expressed in the SAT from the morbidly obese and normal-weight groups (Fold >4, p < 0.01, FDR <0.05); 54 of these were downregulated and 4 were upregulated in morbidly obese subjects. A total of 1,333 target genes were jointly predicted by miRanda and TargetScan. Further bioinformatics analysis showed that the differential miRNAs were involved in 269 significant biological functions and 89 significant signaling pathways. The validation experiment by qRT-PCR showed that the expression levels of miRNA-143-5p, miRNA-143-3p, miRNA-145-5p, and let-7a-5p were downregulated in morbidly obese subjects, consistent with the microarray detection. High-mobility group A2 (HMGA2), a target gene of the downregulated miRNA let-7a-5p, was first found to be upregulated 3.19-fold in the SAT of morbidly obese Chinese women when compared to normal-weight controls.

CONCLUSIONS

MiRNA downregulation is a hallmark of intact SAT in a morbidly obese state. Transcription (DNA-dependent), small-molecule metabolic processes, the MAPK signaling pathway, and cancer-related pathways may play important roles in the occurrence and development of obesity. For the first time, we proved that HMGA2, a target gene of let-7a-5p, is upregulated in the SAT of morbidly obese Chinese women.

Influence of hemoglobinopathies and glucose-6-phosphate dehydrogenase deficiency on diagnosis of diabetes by HbA1c among Tanzanian adults with and without HIV: A cross-sectional study

INTRODUCTION

Hemoglobin A1c (HbA1c) is recommended for diagnosing and monitoring diabetes. However, in people with sickle cell disease (SCD), sickle cell trait (SCT), α-thalassemia or glucose-6-phosphate dehydrogenase (G6PD) deficiency, HbA1c may underestimate the prevalence of diabetes. There are no data on the extent of this problem in sub-Saharan Africa despite having high prevalence of these red blood cell disorders.

METHODS

Blood samples from 431 adults in northwestern Tanzania, randomly selected from the prospective cohort study, Chronic Infections, Comorbidities and Diabetes in Africa (CICADA), were analysed for SCT/SCD, α-thalassemia and G6PD deficiency and tested for associations with the combined prevalence of prediabetes and diabetes (PD/DM) by HbA1c, using the HemoCue 501 HbA1c instrument, and by 2-hour oral glucose tolerance test (OGTT).

RESULTS

The mean age of the participants was 40.5 (SD11.6) years; 61% were females and 71% were HIV-infected. Among 431 participants, 110 (25.5%) had SCT and none had SCD. Heterozygous α-thalassemia (heterozygous α+ AT) was present in 186 (43%) of the participants, while 52 participants (12%) had homozygous α-thalassemia (homozygous α+ AT). Furthermore, 40 (9.3%) participants, all females, had heterozygous G6PD deficiency while 24 (5.6%) males and 4 (0.9%) females had hemizygous and homozygous G6PD deficiency, respectively. In adjusted analysis, participants with SCT were 85% less likely to be diagnosed with PD/DM by HbA1c compared to those without SCT (OR = 0.15, 95% CI: 0.08, 0.26, P < 0.001). When using OGTT, in adjusted analysis, SCT was not associated with diagnosis of PD/DM while participants with homozygous α+ AT and hemizygous G6PD deficiency were more likely to be diagnosed with PD/DM.

CONCLUSIONS

HbA1c underestimates the prevalence of PD/DM among Tanzanian adults with SCT. Further research using other HbA1c instruments is needed to optimize HbA1c use among populations with high prevalence of hemoglobinopathies or G6PD deficiency.

The use of Broca index to assess cut- off points for overweight in adults: A short review

The Broca formula was developed in 1871 by Pierre Paul Broca (a French Army Doctor) to help establish ideal body weight or normal body weight. Initially, the Broca Index (BI) was used to work out the normal weight but was later expanded to ideal Body Weight. Ideal Body weight (kg) = [Height (cm)-100]. The common methods used to explore the levels of adiposity include body mass index (BMI), waist circumference, skinfolds, bioelectrical impedance analysis, dual energy x-ray absorptiometry (DEXA), computerized tomography (CT) and magnetic resonance imaging (MRI). Even though there have been several anthropometric measurements discoveries to assess obesity, BMI is still widely used in many clinic centers around the world. It remains simple and relatively inexpensive to measure and easily obtainable in non-laboratory settings. In this review, we will summarize the common methods used to measure body fat and their limitations. Second, we will show the correlation that may exist between Broca Index and BMI cutoffs. Last, we will underline some potential clinical usefulness that may present Broca index in assessing body fat.

Body mass index and waist-to-hip ratio misclassification of overweight and obesity in Chinese military personnel

BACKGROUND

The rising prevalence of obesity in military personnel has raised great concerns. Previous studies suggest that body mass index (BMI)- and waist-to-hip ratio (WHR)-based obesity classifications in US military personnel and firefighters have high false negative and subsequently cause obesity misclassification.

OBJECTIVE

To determine whether BMI and WHR could reflect the fat mass of Chinese military personnel.

METHODS

Three hundred fifty-three male Chinese military personnel and 380 age-matched male adults were recruited. Obesity classification was defined by BMI, WHR, and body fat percentage (BFP).

RESULTS

Chinese military personnel had extremely low obesity rate determined by either BFP (0.3%) or BMI (0.6%). By combining overweight and obese individuals, BMI- and WHR-determined prevalence of overweight/obesity was 22.4% and 17.0% compared to BFP-based standard (4.0%) (P < 0.05). In reference to BFP, BMI and WHR have high false-positive rate compared to the control group. Further analysis showed that Chinese military personnel consisted of high percentage of BFP^lowBMI^high and/or BFP^lowWHR^high subpopulations. Eighty-one percent of BMI^high and 78.3% of WHR^high of them were BFP low.

CONCLUSIONS

Chinese military personnel has extremely low obesity rate. BMI and WHR have high false-positive rates in reference to BFP, which cannot accurately reflect the mass of adipose tissue and leads to obesity misclassification.

Optimal cut-off values for anthropometric measures of obesity in screening for cardiometabolic disorders in adults

Excessive accumulation of body fat (BF) promotes obesity, whilst posing a significant health hazard. There being no agreed, optimal quantifying methods, application of BF variable in clinical practice is not deemed an effective assessment option. The study, involving 4,735 patients (33.6% men), aged 45-64, aimed to identify optimal cut-off values for anthropometric indicators of obesity to evaluate cardiometabolic risk. A minimum P-value approach was applied to calculate the cut-offs for BF%. Threshold values for body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height (WHTR) ratio, facilitating optimal differentiation of cardiometabolic risk, were based on BF%, expressed as a binary classifier. The newly estimated cut-off values for predicting cardiometabolic risk, based on BMI, were lower than the referential obesity thresholds, whereas the threshold values of WC, WHR, and WHTR were higher. Apart from dyslipidemia, the odds of cardiometabolic disorders were higher, when the anthropometric indicators under study exceeded the cut-off points in both sexes. The proposed cut-offs proved instrumental in predicting cardiometabolic risk, whilst highlighting diagnostic and clinical potential of BF%, whereas BMI boasted the highest predictive potential. Cardiometabolic risk also proved significantly higher even in the overweight patients.

Associations between the neighbourhood characteristics and body mass index, waist circumference, and waist-to-hip ratio: Findings from Alberta's Tomorrow Project

This study estimated the associations between neighbourhood characteristics and self-reported body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) risk categories among Canadian men and women. Using data from the Alberta's Tomorrow Project (n = 14,550), we estimated 3- and 4-way intersections, business destinations, population count, and normalized difference vegetation index (NDVI) within a 400 m radius of participant's home. Intersections, business destinations, and population count (z-scores) were summed to create a walkability score. Four-way intersections and walkability were negatively associated with overweight and obesity. Walkability was negatively associated with obesity. NDVI was negatively associated with high-risk WHR and population count and walkability positively associated with high-risk WHR. Among men, population count and walkability were negatively associated with obesity, and business destinations and walkability were negatively associated with overweight and obesity. Among women, NDVI was negatively associated with overweight (including obesity), obesity, and high-risk WC. Interventions promoting healthy weight could incorporate strategies that take into consideration local built environment characteristics.

Revising BMI Cut-Off Points for Obesity in a Weight Management Setting in Lebanon

Obesity is defined by the World Health Organization (WHO) as a body mass index (BMI) ≥ 30 Kg/m2. This study aimed to test the validity of this BMI cut-off point for adiposity in a weight management clinical setting in Lebanon. This cross-sectional study of 442 adults of mixed gender, categorized by the WHO BMI classification, included: 66 individuals of normal weight, 110 who were overweight and 266 with obesity. The clinical sample was referred to the Outpatient Clinic in the Department of Nutrition and Dietetics at Beirut Arab University (BAU) in Lebanon. All participants underwent anthropometric evaluation. The gold standard for defining obesity was based on the National Institutes of Health (NIH)/WHO guidelines for total body fat percentage (BF%). The best sensitivity and specificity were attained to predict obesity, according to the receiver operating characteristic curve (ROC) analysis. The BMI cut-off point for predicting obesity in the clinical sample was nearly 31.5 Kg/m2, and more than 90% of individuals with obesity and cardiometabolic disease were above this cut-off point. In conclusion, this new BMI cut-off point, an obesity definition higher than suggested in Western populations, was demonstrated to have clinical usefulness. Obesity guidelines in Lebanon, therefore, need revising.

Tracheal Ultrasound for the Accurate Confirmation of the Endotracheal Tube Position in Obese Patients

OBJECTIVES

Obesity is a serious disorder that may lead to numerous difficulties in endotracheal tube (ETT) management. This study investigated the potential of tracheal ultrasound (TUS) for the accurate confirmation of the ETT position in obese patients.

METHODS

A total of 68 obese patients undergoing tracheal intubation were enrolled in this study from January 2017 to June 2018. All patients received auscultation and TUS to evaluate the ETT position, which was ultimately verified by bronchoscopy. A correct position of the ETT was defined as placement at the trachea, whereas placement at the right/left main bronchus was classified as an incorrect position.

RESULTS

We found 58 correct placements of the ETT at the trachea, 8 incorrect placements at the right main bronchus, and 2 incorrect placements at the left main bronchus. Compared with auscultation, TUS showed higher accuracy (85.29% versus 67.65%; P = .005), sensitivity (84.48% versus 67.24%; P = .005), and specificity (90.00% versus 70.00%; P < .001), as well as lower rates of false-positive (10.00% versus 30.00%; P < .001) and false-negative (15.52% versus 32.76%; P = .005) results for detecting the correct placement of the ETT, defined as placement at the trachea.

CONCLUSIONS

Tracheal ultrasound is highly sensitive and specific in confirming the ETT position in obese patients.

Air Pollution as a Cause of Obesity: Micro-Level Evidence from Chinese Cities

Chinese air pollution is obviously increasing, and the government makes efforts to strengthen air pollution treatment. Although adverse health effects gradually emerge, research determining individual vulnerability is limited. This study estimated the relationship between air pollution and obesity. Individual information of 13,414 respondents from 125 cities is used in the analysis. This study employs ordinary least squares (OLS) and multinomial logit model (m-logit) to estimate the impact of air pollution on obesity. We choose different air pollution and Body Mass Index (BMI) indicators for estimation. Empirical results show Air Quality Index (AQI) is significantly positively associated with the BMI score. As AQI adds one unit, the BMI score increases 0.031 (SE = 0.002; p < 0.001). The influence coefficients of particle size smaller than 2.5 μm (PM_2.5), particle size smaller than 10 μm (PM₁₀), carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂) to the BMI score are 0.034 (SE = 0.002; p < 0.001), 0.023 (SE = 0.001; p < 0.001), 0.52 (SE = 0.095; p < 0.001), 0.045 (SE = 0.004; p < 0.001), 0.021 (SE = 0.002; p < 0.001), 0.008 (SE = 0.003; p = 0.015), respectively. Generally, air pollution has an adverse effect on body weight. CO is the most influential pollutant, and female, middle-aged, and low-education populations are more severely affected. The results confirm that the adverse health effects of air pollution should be considered when making the air pollution policies. Findings also provide justification for health interventions, especially for people with obesity.

Functional Foods and Bioactive Compounds: A Review of Its Possible Role on Weight Management and Obesity's Metabolic Consequences

Background: Weight management and obesity prevention is a basic aim of health organizations in order to decrease the prevalence of various metabolic disorders. The aim of the present review article was the evaluation of the possible role of functional foods and their bioactive compounds as alternative way to promote weight management and prevent obesity and its metabolic consequences. Methods: Approximately 100 articles were selected from Scopus, PubMed, Google Scholar, and Science Direct, by using relative key words, and based mainly on recent animal, clinical or epidemiological studies. Results: The literature review highlighted the possible effect of specific functional foods such as coffee, green tea, berries, nuts, olive oil, pomegranate, avocado, and ginger. Specific bioactive compounds of those foods—such as caffeine, catechins, gallic acid, anthocyanins, ascorbic acid, polyphenols, oleuropein, capsaicin, and quercetin—may contribute to weight management, obesity prevention, and obesity’s metabolic consequences. The possible mechanisms include effect on satiety, lipid absorption, fatty acids beta oxidation, stimulation of thermogenesis, etc. Conclusions: Functional foods, as part of a balanced diet, could be useful in the direction of weight management and decrease of obesity’s’ metabolic consequences. However, the scientific evidence is unclear and in most cases controversial and more clinical and epidemiological studies are needed in order to further investigate the mechanisms of their possible effect.

Impact of preoperative anxiety and depression on quality of life before and after resection of hepatocellular carcinoma

OBJECTIVE

The impact of anxiety and depression symptoms (ADS) is often estimated in terms of clinical endpoints such as the risk of complications and probabilities of readmission and survival. The purpose of this study was to provide a benchmark for capturing the negative effects of ADS on quality of life after hepatocellular carcinoma (HCC) surgery and to provide an evidence base for future research and clinical interventions aimed at understanding and remediating these effects.

METHODS

This prospective study analyzed 410 HCC patients at three tertiary academic hospitals. The Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), and Functional Assessment of Cancer Therapy- Hepatobiliary (FACT-H) were administered before HCC surgery and at 6 months, 1 year, and 2 years after HCC surgery. Generalized estimating equations were used to estimate differences-in-differences models for examining the effects of ADS.

RESULTS

At baseline, 9.0% of the participants had anxiety symptom (BAI > 10), 17.1% had depression symptom (BDI > 13), and 7.1% had ADS. Throughout the study period, anxiety and depression (differences-in-differences value) had significant (P < 0.001) negative net effects on mean scores for all FACT-H dimensions, and the differences gradually increased over time. From baseline through all follow-up years, the two groups significantly (P < 0.001) differed in scores for all FACT-H dimensions, and the differences increased over time.

CONCLUSIONS

For healthcare providers, this study highlights the need for continued monitoring for ADS in patients who have undergone hepatic resection and the need for timely and appropriate psychological care for these patients.

The association of body mass index with difficult tracheal intubation management by direct laryngoscopy: a meta-analysis

BACKGROUND

Obesity is a serious disorder and may bring about many difficulties of perioperative management. A systematic review was conducted to assess the association between obesity and difficult intubation.

METHODS

We searched electronic databases for related reviews and references of meta-analyses on August 14, 2017. The databases of PubMed, Embase, and the Cochrane controlled trials register were searched compared obese with non-obese patients in which difficult intubation rate of the adult population were retrieved. Patients with a BMI ≥ 30 kg·m- 2 were considered obese. The primary outcome was difficult tracheal intubation; secondary outcomes were the rates of difficult laryngoscopy and Mallampati score ≥ 3. This review included papers published from 1998 to 2015.

RESULTS

This review included 204,303 participants in 16 studies. There was a statistically significant association between obesity and risk of difficult tracheal intubation (pooled RR = 2.04, 95% CI: 1.16-3.59, p = 0.01; I2 = 71%, p = 0.008, Power = 1.0). It also showed significantly association between obesity and risk of difficult laryngoscopy (pooled RR = 1.54, 95% CI: 1.25-1.89, p < 0.0001; I2 = 45%, p = 0.07, Power = 1.0), obesity and risk of Mallampati score ≥ 3 (pooled RR = 1.83, 95% CI: 1.24-2.69, p = 0.002; I2 = 81%, p < 0.00001, Power = 0.93). However, there were no association of obesity and risks of difficult intubation compared with non-obesity in the cohort studies (pooled RR = 3.41, 95% CI: 0.88-13.23, p = 0.08; I2 = 50%, p = 0.14) and the elective tracheal intubation (pooled RR = 2.31, 95% CI: 0.76-6.99, p = 0.14; I2 = 73%, p = 0.01), no associated with an increased risk of difficult laryngoscopy in the sniffing position (pooled RR = 2.00, 95% CI: 0.97-4.15, p = 0.06; I2 = 67%, p = 0.03).

CONCLUSION

Obesity was associated with an increased risk of difficult intubation, difficult laryngoscopy and Mallampati score ≥ 3 in adults patients undergoing general surgical procedures. However, there were no association of obesity and risks of difficult intubation compared with non-obesity in the cohort studies and the elective tracheal intubation, no associated with an increased risk of difficult laryngoscopy in the sniffing position. Future analyses should explore the association of BMI and difficult airway.