Anthropometric measures are not accurate predictors of fat mass in ALS

Abstract

Background: Anthropometric measurements including body mass index (BMI) and body adiposity index (BAI) are widely employed as indicators of fat mass (FM). Metabolic abnormalities in amyotrophic lateral sclerosis (ALS) impact disease progression, therefore assessment of FM informs care. The aim of this study was to determine whether BMI and BAI are accurate predictors of FM in ALS. Methodology and main findings: BMI, BAI and percentage FM (determined by air displacement plethysmography; FM-ADP) were measured in control (n ¼ 35) and ALS (n ¼ 44) participants. While BMI and BAI correlated significantly with FM-ADP, neither index provided an accurate estimate of FM. In longitudinally assessed ALS participants (n ¼ 29; $six-month repeat assessment interval), although a change in BMI (r 2 ¼ 0.62 r ¼ 0.79 p50.01) and BAI (r 2 ¼ 0.20 r ¼ 0.44, p ¼ 0.02) correlated with a change in FM-ADP, the anthropometric measures did not consistently reflect increases or decreases observed in FM-ADP. Conclusions/significance: Using FM-ADP as the standard, this study suggests that BMI and BAI are not accurate measures of FM in ALS. Furthermore, longitudinal assessments indicate that changes in BMI and BAI do not consistently reflect true changes of FM in ALS.

Loss of appetite is associated with a loss of weight and fat mass in patients with amyotrophic lateral sclerosis

“…By comparison, a change in BMI was only correlated with a change in FFM. We confirm that a change in BMI does not reliably correspond to a change in FM in ALS (46). This supports guidelines in clinical nutrition management in ALS (47) which propose that body weight must be monitored to inform overall dietary status, should routine assessment of body composition not be available.…”

Genome-wide Meta-analysis Finds the ACSL5-ZDHHC6 Locus Is Associated with ALS and Links Weight Loss to the Disease Genetics

“…In this case cohort, we observed no association between the SNPs and weight (rs58854276 p = 0.97 and rs3828599 p = 0.50) or BMI (rs58854276 p = 0.47 and rs3828599 p = 0.33) at first visit. It is important to recognize that BMI and weight do not always accurately reflect changes in fat-free mass in ALS (Ioannides et al, 2017b;Kirk et al, 2019) and that in the case cohorts, individuals have weight measurements taken at cross-sectional times relative to their personal disease trajectory. Here, including time since diagnosis in the analysis did not offer further clarity.…”

Validity of the Body Adiposity Index in Predicting Body Fat in Adults: A Systematic Review

“…As a method of BF% evaluation, its ability to predict cardiovascular disease risk factors and metabolic syndrome has been verified in Chinese adults (8)(9)(10). The method was also used in individuals diagnosed with diseases and with some type of syndrome, such as familial partial lipodystrophy (11), HIV (12), amyotrophic lateral sclerosis (13), chronic kidney disease (14), and Down syndrome (15).…”