Background Juvenile dermatomyositis (JDMS) is a rare but serious inflammatory myositis of childhood with proximal muscle and skin involvement with lipodystrophy (LD) being an important complication. Most studies on JDMS are either on diagnostic or treatment aspects with a paucity of information on the pattern of muscle mass and subcutaneous fat depletion amongst these patients.
Objectives To study the pattern of muscle mass assessed in terms of MUAMC (mid upper arm muscle circumference) & sub-cutaneous fat mass in terms of different skinfold thicknesses (SFT), and to see the correlation between selected anthropometric parameters and different components of lipid profile amongst children with JDMS.
Methods Thirty-five patients (14 male, 21 female) aged between 1 to 22 years diagnosed as cases of JDMS were enrolled in a tertiary care institute in north India. Controls (35) were age and sex matched. All the study subjects underwent standardized anthropometric measurements and 9 different i.e. (biceps, triceps, subscapular, mid-axillary, juxta nipple, 9th rib SFT, malar, suprailiac and paraumbilical) skinfold thicknesses were measured using Harpenden skinfold calipers (Holtain, Dyfed, UK). All absolute skinfold thicknesses were transformed in to their logarithms by formula given Edwards et al. MUAMC was derived using the modified Jelliffe & Jelliffe formula. Lipid profile was measured only in patients
Results Statistically significant (p<0.05) difference was obtained for mid axillary SFT in 1–5 years age group, biceps, triceps and juxta nipple SFT in 10–15 years age, triceps and 9th rib SFT in >15years of age, while none was noted in 5–10 years of age group. In pooled age group biceps, juxta nipple and paraumbilical SFT became statistically significant. Maximum (26.3%) fat loss was recorded for Juxtanipple SFT, while minimum was in suprailiac region (13.6%).The remaining skinfolds enjoyed an intermediate percentage fat loss. 63–71% reduction in c.v was observed for different SFT after log transformation. Overall 97% patients had muscle mass significantly lesser (p<0.01) with mean difference of 2.8±1.9 cm (10%) than controls. No significant correlation was noted between SFT and triglycerides or total cholesterol. Only moderate level significant associations between juxta nipple, malar SFT and LDL as well as between HDL and triceps and malar SFT, shows persistence of interdependence of these two biochemical parameters with only few selected anthropometric measurements of sub cutaneous fat despite influence of the disease.
Conclusions The subcutaneous fat mass and muscle content was substantially reduced in patients as compared to control subjects in our cohort which were site specific and of variable magnitude. Log transformed skinfold thickness to be preferred than absolute values to arrive at logical conclusions on dynamics of subcutaneous fat mass. Further studies are warranted with a larger sample size to arrive at scientifically more meaningful conclusions.
Disclosure of Interest None declared