Nutritional status and vulnerability of older adults/older people (aged 50 +)

I have just supported HelpAge with an assessment of older people (Somali refugees) in Kenya. I write this as sometimes communications between different parts of agencies can be poor (I mean no slight on HelpAge). In brief ... (a) MUAC, Oedema, and BMI. Measurements were MUAC, weight, height, demi-span (DS). DS was measured in case height could not be measured (weakness, kyphosis, scoliosis). When height was not available it was estimated from DS using a formula derived using OLS regression (i.e. height = constant + coefficient * DS) using data from respondents with both height and DS. Primary case-definition was MUAC or oedema since BMI is known to overestimate acute malnutrition in this population (long legs with short trunks). (b) and (c) You should contact the HelpAge surveyor directly. (d) Yes. Limited. You should contact the HelpAge surveyor directly. Any help?

That is a very interesting observation. Low BMI is associated with with increased morbidity and mortality. In women of childbearing age, low BMI is associated with increased risk of having low birth weight babies. BMI is highly correlated with both fat and fat-free mass although the strength of association varies with age, sex, and ethnicity. Most research has concentrated on the use of BMI for estimating the prevalence of chronic undernutrition in stable populations. This is a very different role to screening for acute undernutrition to decide admission to supplementary and therapeutic feeding programs. The assumption in NGO manuals and many academic articles that BMI is an appropriate indicator for screening for acute undernutrition has not been tested. The BMI threshold for severe (i.e. “Grade III”) chronic undernutrition (i.e. BMI < 16) may not reflect the severity of acute undernutrition requiring specialised treatment. Extremely low BMI values were (e.g.) observed in Somalia during the 1992 emergency. This prompted a downward revision of the BMI threshold to BMI < 13 to denote severe wasting. This revision did not account for the Somali long-legs / short-trunk phenotype which is an important explanatory factor behind the very low BMI values observed (see below). This threshold is, therefore. probably inappropriately low and lacking in case-finding sensitivity. Both acute and chronic undernutrition present as low BMI but the process leading to a low BMI may be acute or chronic and the examination of a single BMI value does not allow these two very different conditions to be differentiated from each other. Apart from this major problem, there are several other problems associated with the use of BMI as an anthropometric index. These problems are discussed below. We have to be very careful using BMI because factors other than nutritional status determine the functional significance of BMI values. The most important of these is body shape. Body shape is frequently determined by the sitting height to standing height ratio (SSR): SSR = Sitting Height / Standing Height This index varies considerably both between and within populations. International comparisons have found average SSR to vary between 0.48 (in Australian aborigines) and 0.55 (in Japan). This range translates into differences in BMI due to body shape alone of over 6 BMI units. In one Australian aborigine population, for example, the SSR was found to vary between 0.41 and 0.53. This is larger than the worldwide variation in average SSR and translates into differences in BMI in excess of 10 BMI units due to body shape alone. When BMI is used to assess an individual (as in screening for admission to SFP or TFP), the calculated BMI should be adjusted using a correction factor based on their SSR. This requires an additional measurement (i.e. of sitting height) and several additional calculations (i.e. to calculate SSR and to apply a correction to the calculated BMI). Without this adjustment, sensitivity and specificity of diagnoses based on BMI thresholds may be low. Other factors influencing BMI are diurnal variability in height, diurnal variability in weight, increased error in measuring height in acutely malnourished individuals, loss of height during starvation, problems with oedema and ascites, problems with measuring height in older persons, problems with weight in pregnant and lactating women. MUAC with clinical signs appears to be the better option. The use of MUAC for this purpose was recommended by United Nations Forum for Nutrition in July 2000 (see this guideline).

I was thinking of MSF's Nutrition Guidelines, an OXFAM manual by Helen Young, guidelines from ACF (which even have special thresholds for people aged over 50+), and some articles by Ferro-Luzzi and James. I can find these: Boelaert M, Davis A, Le Lin B, Michelet M, Ritmeijer K, Van Der Kam S et al. (1995) Nutrition guidelines. 1ed. Paris: Médecins Sans Frontières, Paris Young H. (1992) Food scarcity and famine: assessment and response. Oxfam, Oxford Ferro-Luzzi A, James WPT. (1996) Adult malnutrition: simple assessment techniques for use in emergencies. British Journal of Nutrition 75:3-10 But I have lost the ACF guideline ... it related to admission criteria for entry into feeding program and dated from the late 1990's. The question "Why do you think that some agencies are opting ... for BMI in older adults and not MUAC, as recommended by the United Nations Forum for Nutrition in July 2000?" is an interesting one. A similar situation exists regarding the use of W/H in children where the evidence strongly favours MUAC. Some say that it is a love of complicated measures for the sake of complication itself, because "more complicated" is mistaken for "more scientific", and because it places the locus of control of admissions with the program rather than the population. The social scientist Jeremy Freese writes about a special set of ideas that are "... more “vampirical” than “empirical” - unable to be killed by mere evidence - the hypothesis seem so logically compelling that it becomes easy to presume that it must be true, and to presume that the natural science literature on the hypothesis is an unproblematic avalanche of supporting findings". I think that W/H and BMI belong in that set of ideas. The problem is that many schools of public health and nutrition (and many professors of public health and nutrition) have pushed W/H and BMI (and pushed down MUAC) and are unwilling to retract or (if only they would!) keep quiet on the subject. NGOs are also very conservative organisations and many resist evidence-based programming and sport a "not invented here" brand of ignorance. Anyway ... I am not the right person to ask. Can any BMI-booster out there write to let us know why they keep trying to flog this particular dead horse?

Thank you for this. I think you are right. Do you think that this could be remedied by (e.g.) a Field Exchange supplement on assessing malnutrition in adults? This could be an updated version of this guideline with new material explicitly covering (e.g.) monitoring of nutritional status in HIV / ARV programs, detection of malnutrition in clinical settings, screening, prevalence surveys, older people, PLWs, &c. Is there a demand for this sort of thing? I'd be happy to help with this.