Assessment of current nutritional status (CNS) in children and adults using weight-length/height standard deviation score (SDS) difference

<title>Abstract</title> <p>Background When assessing current nutritional status (CNS) in children and adults, commonly used weight- and length/height-based indices – such as weight-for-length/height, body mass index (BMI), BMI-for-age, tri-ponderal mass index (TMI), and ponderal index (PI) – have shown clear limitations regarding sex, age, shortness and/or tallness. Therefore, this study attempted to propose a novel index capable of assessing CNS while countering these specific limitations. Methods According to the literature, for individuals of the same sex and age, children with ideal CNS (ICNS) and malnutrition remain associated with weights and lengths/heights of same ranks and discordant ranks, respectively. Thus, for children with weights and lengths/heights of the same SD scores (SDSs), ICNS can be indicated mathematically by a weight-length SDS differenc (WLSDS-d) or weight-height SDS difference (WHSDS-d) of ‘0’ (zero). Similarly, for children with weights-lengths/heights of different SDSs, WLSDS-ds/WHSDS-ds (i.e., SDSs of weights relative to associated lengths/heights) of &lt; − 3, &lt; − 2, − 2 to + 1, &gt; + 1, &gt; + 2 and &gt; + 3 indicate the conditions of severe wasting/thinness/underweight, moderate wasting/thinness/underweight, normal CNS, risk of overweight (overweight for children above 5 years), overweight (obesity for children above 5 years), and obesity, respectively. Furthermore, for adults with weights and heights of the same or different SDSs for the same sex (with respect to the oldest reference children), conditions of ICNS, severe thinness/underweight, moderate thinness/underweight, mild thinness/underweight, normal CNS, overweight, obesity class I, obesity class II and obesity class III can be indicated by WHSDS-ds of 0, &lt; − 3, &lt; − 2, − 1 to + 1, &gt; + 1, &gt; + 2, &gt; + 3 and &gt; + 4, respectively. Therefore, WLSDS-d/WHSDS-d was (1) proposed as an index of CNS, (2) used to assess the CNS of select children and adults (using exemplary weight and length/height data), and (3) compared with the aforementioned indices regarding the assessed CNS. Results The study demonstrated that WLSDS-d/WHSDS-d, weight-for-length/height, and BMI-for-age all successfully indicated ICNS for children whose weights and lengths/heights matched the standard/reference medians for their same sex and age. Furthermore, the study revealed the following regarding body index inaccuracies: (a) weight-for-length/height, BMI and BMI-for-age (i) underestimated ICNS in both shorter-cum-lighter and lengthier/taller-cum-heavier individuals, (ii) overestimated wasting/thinness/underweight status while underestimating overweight and obesity in shortercum-lighter individuals, and (iii) underestimated wasting/thinness/underweight status while overestimating overweight and obesity in lengthier/taller-cum-heavier individuals; and (b) TMI and PI overestimated overweight and obesity in shorter-cum-lighter individuals and underestimated them in lengthier/taller-cum-heavier individuals. The study also showed a high correlation of WLSDS-d/WHSDS-d with BMI, BMI-for-age, TMI and PI in both children and adults. Conclusion The proposed WLSDS-d/WHSDS-d index assessed CNS continuously from children to adults, reflecting sex- and age-based variations in body fat and relative weight status, countering the age, sex, shortness-cum-lightness and/or lengthiness/tallness-cum-heaviness related limitations of weight-for-length/height, BMI, BMI-for-age, TMI, and/or PI.</p>