Development and Cross-Validation of a Simple Model to Estimate Percent Body Fat in Persons with Multiple Sclerosis

Usefulness of bioelectrical impedance analysis in multiple sclerosis patients-the interrelationship to the body mass index

Background

Patients with multiple sclerosis (MS) have many potential factors (disease duration, spasticity, immobilization, or glucocorticoid use) that can deteriorate their nutritional status and impact both the progression and prognosis of the disease. Body mass index (BMI), the most widely used nutritional status assessment tool, has important limitations because it does not provide any data on body composition.

Aim

This study aimed to assess the interrelationship between nutritional status assessment by both body mass index (BMI) and body composition using bioelectrical impedance analysis (BIA) and the consistency of diagnosis for underweight/underfat, normal weight/healthy, overweight/overfat, and obesity/obese MS patients.

Methods

Anthropometric [BMI and waist-to-height ratio (WHtR)] and body composition (BIA) data were evaluated in 176 patients with MS. Patients were categorized into four nutritional status subgroups (underweight, normal weight, overweight, obese according to BMI, and underfat, healthy, overfat, and obese according to fat mass% by BIA). The median Expanded Disability Status Scale score was 4.5. Patients were then divided according to EDSS score as mild (EDSS 1.0-4.0) or moderate (EDSS 4.5-6.5) disability subgroups.

Results

Based on BIA assessment, there was a significantly higher prevalence of overfat than of overweight based on BMI [n = 50 (28.41%) vs. n = 38 (21.59%); p < 0.05]. However, the prevalence of obesity did not differ significantly regardless of the mode of diagnosis and was not significantly lower when assessed using BIA [n = 26 (14.77%) vs. n = 30 (17.05%), respectively]. The overall compatibility rates (CR) of diagnoses made using both BMI and BIA were 75.6, 77.0, and 70.1% for all patients with MS and the mild and moderate subgroups, respectively. The lowest CR was observed in the overweight group. Adiposity significantly underestimated BMI in all subgroups. In the moderate MS subgroup, BMI significantly overcategorized patients with MS as having a normal weight (p < 0.05). Stratification for abdominal obesity (WHtR > 0.5) showed that BMI significantly underestimated the prevalence of MS in overweight and obese vs. overfat and obese patients, as assessed using BIA (60.5 vs. 67%; p < 0.05). Clinical status (EDSS and ΔEDSS) was more closely related to the nutritional status categorized by FAT% assessed using BIA than using BMI cutoff points. However, the relationship was not statistically significant.

Conclusion

Using the BMI cutoff point for nutritional status assessment in patients with MS is associated with a significant underestimation of excess fat mass. BIA-based FAT% based on BIA have a better relationship with abdominal obesity and disability status than with BMI in patients with MS. The highest rate of false-negative diagnoses was based on the BMI in patients with MS and moderate disability. Adiposity assessment using BIA appears to be a useful method for proper nutritional status assessment in the patients group.

Body Composition in Multiple Sclerosis Patients and Its Relationship to the Disability Level, Disease Duration and Glucocorticoid Therapy

Background: Patients with multiple sclerosis (MS) have many potential factors (spasticity, immobilization, glucocorticoids use) for the deterioration of body composition. Aim: To assess the nutritional status (by classical anthropometry and by bioelectrical impedance analysis (BIA)) in MS patients and to correlate it with clinical state, MS duration time and the presence of glucocorticoid therapy in anamnesis (ever used). Methods: Anthropometrical (BMI and waist and hip circumferences, waist-to-height ratio (W/HtR), and waist-to-hip ratio (WHR)) and body composition (BIA) data were evaluated in 176 patients with MS. Fat mass (FM), and fat-free mass (FFM) were expressed as kilograms (kg), percentage (%) and indexes (FMI: fat mass index, FFMI: fat-free mass index) expressed in kg/m2. The median Expanded Disability Status Scale score was 4.5. Patients were then divided according to EDSS score as mild (EDSS 1.0−4.0) or moderate (EDSS 4.5−6.5) disability subgroup. Results: Waist c., WHtR, WHR, and FM% were significantly higher in the moderate MS group (p < 0.01; p < 0.001; p < 0.001; and p < 0.05, respectively). Whilst, FFM% was significantly lower (p < 0.05). BMI did not correlate significantly with any disability status score and MS time. Significant correlations were observed between EDSS, ΔEDSS and MS time and Waist c., WHtR, WHR, FM% and FFM%. WHtR had the strongest significance (p < 0.0001 vs. EDSS; p < 0.0001 vs. ΔEDSS; and p < 0.01 vs. MS time, respectively). After the adjustment to the MS time, only FM% was no longer significantly related to both EDSS and ΔEDSS. MS duration time, EDSS, ΔEDSS, WHtR, FM(kg), FM%, and FMI were significantly higher in the patients with a positive history of glucocorticoid therapy (all p < 0.05). Whilst, FFM% was significantly lower in MS patients treated with glucocorticoids (p < 0.01). Conclusions: Greater disability in MS patients is strongly related to lower fat-free mass and higher fat mass, especially with the abdominal distribution, irrespective of the duration time of the disease. Oral glucocorticoid therapy seems to have a negative impact on the body composition of MS patients. However, further prospective multifactorial studies in this field have to be done. For the proper assessment of nutritional status in MS patients, Waist c., WHtR, WHR, or body composition parameters seem to be of greater use than BMI.