Research Article: The association between neck adiposity and long-term outcome

Date Published: April 23, 2019

Publisher: Public Library of Science

Author(s): Sigal Tal, Ilya Litovchik, Miriam M. Klar, Hillel S. Maresky, Noam Grysman, Itay Wiser, Itzhak Vitkon-Barkay, Gil Marcus, Oran Tzuman, David Pereg, Victoria Rum, Tomer Ziv-Baran, Shmuel Fuchs, Sa’ar Minha, Giacomo Pucci.

http://doi.org/10.1371/journal.pone.0215538

Abstract

Anthropometric indices of obesity (e.g. body mass index, waist circumference and neck circumference) are associated with poor long-term cardiovascular outcome. Prior studies have associated neck circumference and central body adiposity. We explored the association between neck fat volume (NFV) and long-term cardiovascular outcome. The study provides a retrospective analysis of all patients undergoing computerized tomography angiography for suspected cerebrovascular accident between January and December 2013. NFV was assessed by three dimensional reconstructions and was adjusted to height to account for differences in body sizes, thus yielding the NFV/height ratio (NHR). Univariate and multivariate analysis were utilized to explore the association between various indices including NHR and all-cause mortality. The analysis included 302 patients. The average age was 61.9±14.3 years, 60.6% of male gender. Diabetes mellitus, hypertension and cardiovascular disease were frequent in 31.5%, 69.9%, and 72.2% of patients, respectively. The median NHR was 492.53cm2 [IQR 393.93–607.82]. Median follow up time was 41.2 months, during which 40 patients (13.2%) died. Multivariate analysis adjusting for age, sex, and diabetes mellitus indicated an independent association between the upper quartile of NHR and all-cause mortality (hazard ratio = 2.279; 95% CI = 1.209–4.299; p = .011). NHR is a readily available anthropometric index which significantly correlated with poor long-term outcome. Following validation in larger scale studies, this index may serve a risk stratifying tool for cardiovascular disease and future outcome.

Partial Text

Obesity is global epidemic associated with increased morbidity and mortality. Defined as an abnormally high proportion of adipose tissue, obesity assessment is traditionally based on body weight, although body weight doesn’t necessarily correlate with the proportion of body fat content. Conversely, anthropometric indices describing fat distribution, such as waist-to-hip ratio, have been shown to identify patients with increased cardiovascular risk better than indices based on weight (i.e. body mass index [BMI]) [1, 2]. Furthermore, percentage of body fat is linearly correlated with mortality while this is not the case for BMI [3]. Visceral, abdominal, and liver fat, as measured by computed tomography (CT), have demonstrated associations with increased cardiovascular risk and poor outcome [4–6]. Similar to abdominal (waist) circumference, neck circumference emerged as a readily available anthropometric index, which has also demonstrated associations with cardiovascular risk factors and with poor outcome [7–11].

Of the 352 patients presenting with CVA during the outlined time period, 16 were excluded due to the presence of oncological comorbidities and 34 were excluded due to missing data regarding patient height. A total of 302 patients that underwent CTA for suspected stroke were included in the final statistical analysis. Median length of follow up 41.17 months (IQR [37.6–43.97]). Mean age (±SD) of the study population was 61.9±14.3 years, 60.6% of male gender. The prevalence of diabetes mellitus, hypertension and dyslipidemia was 31.5%, 69.6% and 72.5% respectively. The mean BMI was 27.1±4.7. Patient descriptive characteristics are further described in Table 1. An NHR of 607.8 cm2 was found to be the value separating the lower three quartiles from the upper quartile. As detailed in Table 2, patients in the upper quartile of the NHR had higher prevalence of diabetes mellitus, hypertension, dyslipidemia, chronic kidney disease and ischemic heart disease but had a higher mean BMI (42.7% vs, 27.8%, 85.3% vs. 64.8%, 17.3% vs. 4.0%, 37.7% vs, 20.7% and 30.8±5.3 vs. 25.9±3.8 kg/m2 respectively; p-values<0.05 for all). During follow-up 40 patients (13.2%) expired. Kaplan-Meier survival curve (Fig 1) demonstrates poor outcome of patients in the upper quartile of NHR compared with those in the other quartiles. The main result of the current study indicates that in an intermediate-to-high risk patient population referred to CTA for CVA exclusion, larger volume of neck adipose tissue is independently associated with long term mortality. In conclusion, high NHR is independently associated with long term all-cause mortality. After validation in larger scale studies, this simple metric may be useful a screening aid to assess patients’ cardiovascular risk and long term outcome.   Source: http://doi.org/10.1371/journal.pone.0215538

 

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