Arm Span as an Alternative to Standing Height for Calculation of Body Mass Index (BMI) amongst older Adults

Objectives: Accurate measurement of height is difficult in older adults because of the reduction in height that occurs during the ageing process. Therefore, several western studies have demonstrated the arm span as an alternative anthropometric measurement to height among older adults, as the length of arm span is less affected by aging. The aim of the study was to use arm span as an alternative to standing height for calculation of body mass index (BMI) amongst older adults. Methodology: A community-based cross sectional study was carried out during 2011-12 among 400 (Men: 180; Women: 220) urban geriatric population (age 60-years and over)of the town of Khammam. Weight, height and arm span were measured with standard procedures. Nutritional status of older adults was calculated by body mass index (BMI) classification using both height and arm span. Key Results: The mean (SD) height and arm span among men were 164.5 cm (6.6) and 175.3cm (7.9), respectively, while among women were 149.5cm (5.8) and 158.7cm (8.6). The mean difference between arm span and height was 10.8cm (10.1,11.4)in men and 9.2cm (8.3,10.0) in women (p<0.001). Similarly, significant (p<0.001) differences were observed between the BMIs derived using both height and arm span among both the genders. Conclusion: The conventional height is not a reliable anthropometric measurement for the assessment of nutritional status of older adults, where the BMI-height model over estimated the nutritional status of older adults compared to the BMIarm span model. Therefore, arm span is the best alternative to height for calculation of body mass index (BMI) in older adults. DOI : 10.14302/issn.2379-7835.ijn-15-903 Corresponding Author: Dr N. Arlappa, MD. Scientist ‘E’, Division of Community Studies, National Institute of Nutrition, ICMR, Jamai-Osmania (P.O), Hyderabad – 500 007, India. Tel: 91-40-27197275. fax: 91-40-27019141, Email: arlappan@yahoo.com


Introduction
Anthropometric measurements such as weight and height provide simple, non-invasive methods for assessing the nutritional status of populations 1 and height is an important measure of body size and for the assessment of nutritional status in children and adults 2 .
Height is also an important parameter used to calculate creatinine height index, basal energy expenditure, basal metabolic rate, vital capacity 3 , nutrient requirements 4 as well as for the calculation of body composition 5 .
Therefore, accurate measurement of height is essential for the assessment of nutritional status of individuals 6,7 as they are at risk of malnutrition 8,9 . Height is measured with the subject standing erect on a plain surface without shoes and the head positioned in Frankfurt horizontal plane. The Frankfurt plane is defined as the line joining the inferior margin of the orbit (orbitale) and the tragus of the ear lies in the horizontal plane 10,11 . Aging is associated with physiological, psychological and biological changes 12 . Similarly, as the physical activity levels declines with aging, there will be a change in body composition such as an increase in fat mass and a decrease in lean muscle and bone masses 12 . Accurate anthropometric measurements in older adults might be difficult to obtain because of changes in body composition, posture, mobility, thinning of intervertebral discs leading to a reduction in height during the aging process 13,14 . Similarly, as the measurement of height amongst some patients of an aging population is difficult and unrealistic because of their physical handicap, inability to ambulate, kyphoscoliosis, lower limb contracture and osteoarthritis of hips and knees 15,16 . Standing height is also difficult to measure in older adults with paralysis and amputated lower limbs 17

Study design and Participants.
A community based cross-sectional study was

Ethical Clearance and Consent
The study was approved by the Principal &

Results
The mean (SD) age and anthropometric variables of older adults by gender are presented in as compared to women (9.2 cm) (Fig.1). The correlation between arm span and height was higher amongst men (r = 0.82) as compared to women (r=0.68) (Fig.2&4) (Fig.6-8).
Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) calculated between newly derived BMI-arm span cut-off values and BMIheight cut-off values are presented in Table 6. The sensitivity ranged from 0.76 to 0.88 for any BMI category, while the specificity ranged from 0.90 to 0.99.

Discussion
The relationship between arm span and height as well as estimation of height from long skeletal bones amongst different age groups and gender was studied by different authors in India. However, such studies   were not readily available amongst the geriatric population in India. Our study, is the first of its kind to study the relationship between length of the arm span and standing height amongst the older adults in India.
In general, significant (p<0.001) differences were observed between the mean arm span and height as well as in BMIs calculated using both arm span and height amongst older adults of both genders.
The length of the arm span in both genders was significantly (p<0.001) higher than their standing height and the difference was relatively higher amongst men (10.8 cm) as compared to women (9.2 cm). The difference between arm span and height amongst Malaysian elderly men (7.7 cm) and women (6.1cm) was comparable to the present study 50 . However, Kwok et al (2001)reported no difference between the length of the arm span and height amongst Chinese elderly men (6.4cm) and women (6.3cm) 51 .While, in general, Allen (1989) reported the mean difference between arm span and height as 4.7 cm (range -5 to + 17) amongst the elderly 24 . As reported by Fatmah, the sensitivity of predicted body height from arm span to assess the nutrition status compared to the normal nutrition in elderly male and female is high 28 .
Assessment of nutritional status of the status of the aging population older people is very essential.
However, the assessment of their nutritional status using standing height will lead to misclassification of their nutritional status, because of reduction of height associated with ageing. This would adversely impact on the health and nutritional interventions amongst the aged. Therefore, there is a need of alternative anthropometric measurement to height for the accurate assessment of nutritional status amongst older adults.
Since arm length is less affected than the height by the aging process, it should be considered as an alternative to stature when assessing the nutritional assessments of the elderly 6