Waist-To-Hip Ratio Predicts Abnormal Overnight Oximetry in Men Independent of Body Mass Index.

Background: Ambulatory overnight oximetry (OXI) has emerged as a cost-effective initial test for sleep disordered breathing. Obesity is closely associated with obstructive sleep apnea (OSA); however, whether body mass index (BMI) or waist-to-hip ratio (WHR) predicts abnormal overnight OXI remains unknown. Methods: We performed a retrospective cross-sectional study of 393 men seen in the Executive Health Program at Mayo Clinic in Rochester, Minnesota who underwent ambulatory overnight OXI ordered by preventive medicine physicians between January 1, 2004 through December 31, 2010. We compared participant/spouse-reported symptoms (sleepiness, snoring), physician indications for OXI (obesity, fatigue), Epworth Sleepiness Scale scores, anthropomorphic measurements (WHR, BMI), and comorbid medical conditions (hypertension, diabetes) with OXI results. Results: 295 of the 393 men who completed OXI had abnormal results. During multivariate analysis, the strongest independent predictor of abnormal OXI for men was WHR (≥1.0, OR = 5.59) followed by BMI (≥30.0 kg/m2, OR = 2.75), age (≥55 yrs, OR = 2.06), and the presence of snoring (OR = 1.91, P < 0.05 for all). A strong association was observed between WHR and abnormal OXI in obese (BMI ≥ 30.0 kg/m2, OR = 6.28) and non-obese (BMI < 29.9 kg/m2, OR = 6.42, P < 0.01 for both) men. Furthermore, 88 men with abnormal OXI underwent polysomnography with 91% being subsequently diagnosed with OSA. Conclusions: In ambulatory, predominantly middle-aged men undergoing preventive services evaluation many physician indications for OXI were not predictors of abnormal results; however, WHR strongly predicted abnormal OXI in obese and non-obese men. As such, we suggest middle-aged men who snore and have a WHR ≥1.0 should be directly referred to a sleep clinic for polysomnography.

Normal-Weight Central Obesity: Implications for Total and Cardiovascular Mortality.

BACKGROUND: The relationship between central obesity and survival in community-dwelling adults with normal body mass index (BMI) is not well-known. OBJECTIVE: To examine total and cardiovascular mortality risks associated with central obesity and normal BMI. DESIGN: Stratified multistage probability design. SETTING: NHANES III (Third National Health and Nutrition Examination Survey). PARTICIPANTS: 15,184 adults (52.3% women) aged 18 to 90 years. MEASUREMENTS: Multivariable Cox proportional hazards models were used to evaluate the relationship of obesity patterns defined by BMI and waist-to-hip ratio (WHR) and total and cardiovascular mortality risk after adjustment for confounding factors. RESULTS: Persons with normal-weight central obesity had the worst long-term survival. For example, a man with a normal BMI (22 kg/m2) and central obesity had greater total mortality risk than one with similar BMI but no central obesity (hazard ratio [HR], 1.87 [95% CI, 1.53 to 2.29]), and this man had twice the mortality risk of participants who were overweight or obese according to BMI only (HR, 2.24 [CI, 1.52 to 3.32] and 2.42 [CI, 1.30 to 4.53], respectively). Women with normal-weight central obesity also had a higher mortality risk than those with similar BMI but no central obesity (HR, 1.48 [CI, 1.35 to 1.62]) and those who were obese according to BMI only (HR, 1.32 [CI, 1.15 to 1.51]). Expected survival estimates were consistently lower for those with central obesity when age and BMI were controlled for. LIMITATIONS: Body fat distribution was assessed based on anthropometric indicators alone. Information on comorbidities was collected by self-report. CONCLUSION: Normal-weight central obesity defined by WHR is associated with higher mortality than BMI-defined obesity, particularly in the absence of central fat distribution. PRIMARY FUNDING SOURCE: National Institutes of Health, American Heart Association, European Regional Development Fund, and Czech Ministry of Health.

Leptin, adiposity, and mortality: results from the National Health and Nutrition Examination Survey III, 1988 to 1994.

OBJECTIVE: To determine whether leptin is related to all-cause and cardiovascular (CV) mortality in older adults. PATIENTS AND METHODS: Participants 60 years and older with plasma leptin level measurements from the National Health and Nutrition Examination Survey III (1988-1994) and mortality data linked to the National Death Index were included. We created sex-specific tertiles of leptin (men: 4.2-7.7 µg/L; women: 11.5-21.4 µg/L) to identify the effect of leptin on all-cause and CV mortality. We also determined whether leptin predicted mortality in patients with obesity. We classified obesity using 4 possible definitions: body mass index 30 kg/m(2) or greater; body fat 25% or more in men and 35% or more in women; waist circumference 102 cm or greater in men and 88 cm or greater in women; and waist-hip ratio 0.85 or higher in women and 0.95 or higher in men. Sex-specific proportional hazard models were used to assess the effect of leptin on all-cause and CV mortality. RESULTS: Of 1794 participants, 51.6% were women; the mean age was 70.3±0.4 years, and the follow-up period was 12.5 years with 994 deaths (469 were CV deaths). All-cause mortality in the highest leptin tertile was significant neither in men (hazard ratio [HR], 1.23; 95% CI, 0.93-1.63) nor in women (HR, 0.97; 95% CI, 0.68-1.40). CV mortality was the highest in the highest leptin tertile in men (HR, 1.69; 95% CI, 1.06-2.70) but not in women (HR, 1.21; 95% CI, 0.73-1.98). Evaluating the effect of leptin in subgroups of different obesity definitions, we found that high leptin levels as predict CV mortality in men as measured by waist circumference or body fat. CONCLUSION: Elevated leptin level is predictive of CV mortality only in men. Leptin may provide additional mortality discrimination in obese men.

Decreased exercise capacity and sleep-disordered breathing in patients with hypertrophic cardiomyopathy.

BACKGROUND: Mechanisms of decreased exercise capacity in patients with hypertrophic cardiomyopathy (HCM) are not well understood. Sleep-disordered breathing (SDB) is a highly prevalent but treatable disorder in patients with HCM. The role of comorbid SDB in the attenuated exercise capacity in HCM has not been studied previously. METHODS: Overnight oximetry, cardiopulmonary exercise testing, and echocardiographic studies were performed in consecutive patients with HCM seen at the Mayo Clinic. SDB was considered present if the oxygen desaturation index (number of ≥ 4% desaturations/h) was ≥ 10. Peak oxygen consumption (VO2 peak) (the most reproducible and prognostic measure of cardiovascular fitness) was then correlated with the presence and severity of SDB. RESULTS: A total of 198 patients with HCM were studied (age, 53 ± 16 years; 122 men), of whom 32% met the criteria for the SDB diagnosis. Patients with SDB had decreased VO2 peak compared with those without SDB (16 mL O2/kg/min vs 21 mL O2/kg/min, P < .001). SDB remained significantly associated with VO2 peak after accounting for confounding clinical variables (P < .001) including age, sex, BMI, atrial fibrillation, and coronary artery disease. CONCLUSIONS: In patients with HCM, the presence of SDB is associated with decreased VO2 peak. SDB may represent an important and potentially modifiable contributor to impaired exercise tolerance in this unique population.

Normal weight obesity and functional outcomes in older adults.

BACKGROUND: Obesity defined by body mass index (BMI) is associated with higher levels of functional impairment. However, BMI strata misrepresent true adiposity, particularly in those with a normal BMI but elevated body fat (BF%) (normal weight obesity [NWO]) whom are at higher metabolic and mortality risk. Whether this subset of patients is associated with worsening functional outcomes is unclear. METHODS: Subjects aged ≥60 years with a BMI ≥18.5 kg/m(2) from NHANES III (1988-1994) were included. We created sex-specific tertiles of BF%. Data on physical limitations (PL), instrumental (IADL) and basic activities of daily living (BADL) were obtained. The analysis focused on the association between NWO and these outcomes. Comparative rates among each tertile using logistic regression (referent=lowest tertile) were assessed, incrementally adding co-variates. RESULTS: Of the 4484 subjects aged ≥60 years, 1528 had a normal BMI, and the range of the mean age of tertiles was 69.9-71.2 years. Lean mass was lowest in the elevated BF% group than in the middle or low tertiles (42.6 vs 44.9 vs 45.8; p<0.001). Those with NWO had higher PL risk than the referent in females only in our adjusted model (males OR 1.18 [0.63-2.21]; females OR 1.90 [1.04-3.48]) but not after incorporating lean mass (males OR 1.11[0.56-2.20]; females (1.73 [0.92-3.25]). Neither sex with high BF% had higher IADL risk than the corresponding tertiles (males OR 0.67 [0.35-1.33]; females OR 1.20 [0.74-1.93]). NWO was protective in males only (OR 0.28 [0.10-0.83]) but not in females (OR 0.64 [0.40-1.03]). CONCLUSIONS: NWO is associated with increased physical impairment in older adults in females only, highlighting the importance of recognizing the association of obesity with disability in elders.

Normal weight obesity and mortality in United States subjects ≥60 years of age (from the Third National Health and Nutrition Examination Survey).

Current body mass index (BMI) strata likely misrepresent the accuracy of true adiposity in older adults. Subjects with normal BMI with elevated body fat may metabolically have higher cardiovascular and overall mortality than previously suspected. We identified 4,489 subjects aged ≥60 years (BMI = 18.5 to 25 kg/m(2)) with anthropometric and bioelectrical impedance measurements from the National Health and Nutrition Examination Surveys III (1988 to 1994) and mortality data linked to the National Death Index. Normal weight obesity (NWO) was classified in 2 ways: creation of tertiles with highest percentage of body fat and body fat percent cutoffs (men >25% and women >35%). We compared overall and cardiovascular mortality rates, models adjusted for age, gender, smoking, race, diabetes, and BMI. The final sample included 1,528 subjects, mean age was 70 years, median (interquartile range) follow-up was 12.9 years (range 7.5 to 15.3) with 902 deaths (46.5% cardiovascular). Prevalence of NWO was 27.9% and 21.4% in men and 20.4% and 31.3% in women using tertiles and cutoffs, respectively. Subjects with NWO had higher rates of abnormal cardiovascular risk factors. Lean mass decreased, whereas leptin increased with increasing tertile. There were no gender-specific differences in overall mortality. Short-term mortality (<140 person-months) was higher in women, whereas long-term mortality (>140 person-months) was higher in men. We highlight the importance of considering body fat in gender-specific risk stratification in older adults with normal weight. In conclusion, NWO in older adults is associated with cardiometabolic dysregulation and is a risk for cardiovascular mortality independent of BMI and central fat distribution.