Different equations for determining height among the elderly: the Bambuí Cohort Study of Aging

Mortality risk relationship using standard categorized BMI or knee-height based BMI - does the overweight/lower mortality paradox hold true?

BACKGROUND

The body mass index (BMI) is prone to misclassification of obesity due to age-related height loss and resulting measurement errors. Knee-height based BMI (KH-BMI) has not been previously studied in relation to mortality risk in older adults.

AIM

To evaluate the age- and sex-specific mortality risk relationship using classic BMI and knee height predicted BMI (KH-BMI) overweight and obesity in a 15-year follow-up study including older Swedish adults aged 60-93 years.

METHODS

A 15-year follow-up study among 2,786 individuals aged ≥ 60 years. Height, weight and KH were measured. KH-predicted height was estimated using formulated gender-specific equations. Classic BMI and KH-BMI (kg/m2) were calculated. Mortality data was obtained from the Swedish death registry. Questionnaires were used to collect data on obesity-related lifestyle factors and comorbidities.

RESULTS

Cox regression revealed that using the classic BMI, when comparing with the normal/underweight reference group, there was a mortality risk among overweight men (HR = 0.67, 0.52-0.87), overweight women (HR = 0.79, 0.65-0.97), and obese men (HR = 0.60, 0.41-0.89) aged ≥ 80 years old. Using the KH-BMI, only overweight men and overweight women aged ≥ 80 years had a lower mortality risk, men (HR = 0.71, 0.55-0.92); women (HR = 0.77, 0.62-0.95) after adjusting for obesity-related lifestyle factors and comorbidities.

DISCUSSION

There is evidence that obesity is overestimated by the BMI, in comparison with the KH-BMI classification. In terms of mortality risk and after adjusting for height, there remains a paradoxical protective association between overweight and mortality.

CONCLUSION

Regardless of classic BMI or KH-BMI estimation, overweight men and women aged ≥ 80 years had a lower mortality risk compared to normal/underweight men and women ≥ 80 years.

Estimating the height of elderly nursing home residents: Which equation to use?

Estimating equations can be used when measuring the height of elderly persons is not possible. However, such methods are not always applicable; therefore, it is necessary to consider several aspects, such as sex, age, and ethnicity of the studied population to generate these equations. This study aimed to compare and validate methods of estimating the height of the Brazilian elderly nursing home residents. An accuracy study was conducted with 168 elderly persons. A total of 23 equations were quantitatively evaluated by plotting the differences in means, the Student's t-test for paired samples, the coefficient of determination (R2), the root-mean-square error (RMSE), the interclass correlation coefficient (ICC), and by graphic analysis of the residuals. A significance value of p <0.05 was adopted. An equation was considered applicable when it had R2 >0.7, the lowest RMSE among the equations evaluated, ICC >0.7, and a confidence interval of 95%, with the smallest difference between the upper and lower limits. A greater mean height was noted among younger elderly persons and elderly men compared to up to 80 years and women elderly. Quantitative analysis revealed that equation for Puerto Ricans, using knee height and age, was the most applicable for the overall population (ICC = 0.802). The same equation was applicable for the elderly Brazilian male participants (ICC = 0.838) and for those aged 60-69 years (ICC = 0.895). None of the equations used were applicable for the height estimation of elderly women or individuals aged 70 years or more.

Estimation of true height: a study in population-specific methods among young South African adults

Objective

To investigate the accuracy of arm-associated height estimation methods in the calculation of true height compared with stretch stature in a sample of young South African adults.

Design

A cross-sectional descriptive design was employed.

Setting

Pietermaritzburg, Westville and Durban, KwaZulu-Natal, South Africa, 2015.

Subjects

Convenience sample (N 900) aged 18–24 years, which included an equal number of participants from both genders (150 per gender) stratified across race (Caucasian, Black African and Indian).

Results

Continuous variables that were investigated included: (i) stretch stature; (ii) total armspan; (iii) half-armspan; (iv) half-armspan ×2; (v) demi-span; (vi) demi-span gender-specific equation; (vii) WHO equation; and (viii) WHO-adjusted equations; as well as categorization according to gender and race. Statistical analysis was conducted using IBM SPSS Statistics Version 21.0. Significant correlations were identified between gender and height estimation measurements, with males being anatomically larger than females (P<0·001). Significant differences were documented when study participants were stratified according to race and gender (P<0·001). Anatomical similarities were noted between Indians and Black Africans, whereas Caucasians were anatomically different from the other race groups. Arm-associated height estimation methods were able to estimate true height; however, each method was specific to each gender and race group.

Conclusions

Height can be calculated by using arm-associated measurements. Although universal equations for estimating true height exist, for the enhancement of accuracy, the use of equations that are race-, gender- and population-specific should be considered.

Indicadores nutricionais combinados e fatores associados em população Quilombola no Sudoeste da Bahia, Brasil

Este estudo estimou a prevalência de duas combinações de indicadores nutricionais: Índice de Massa Corporal (IMC) + Circunferência da Cintura (CC) e IMC + Razão Cintura Estatura (RCE), e investigou os fatores associados em adultos Quilombolas. Amostra aleatória em dois estágios de 739 adultos ≥ 20 anos, residentes em Comunidades Quilombolas em Vitória da Conquista (BA), em 2011. Risco combinado IMC + RCE incluiu os indivíduos que simultaneamente apresentaram IMC ≥ 25,0Kg/m2 ou ≥ 27,0Kg/m2, se idade ≥ 60 anos e RCE ≥ 0,5. O risco IMC + RCE incluiu indivíduos com IMC elevado que também apresentavam CC ≥ 80cm, se mulher, ou ≥ 94cm, se homem. As prevalências dos indicadores nutricionais combinados foram de 35,3% (IMC + RCE) e 26,8% (IMC + CC). Sexo feminino e hipertensão aumentaram a chance para os dois indicadores enquanto que o estado civil não casado diminuiu esta chance. O indicador IMC + RCE foi maior na faixa etária de 40 a 59 anos e o indicador IMC + CC foi mais frequente na faixa de 40 a 49 anos. A baixa escolaridade elevou o indicador IMC + RCE, enquanto assistir televisão por mais de duas horas por dia, o indicador IMC + CC. A elevada prevalência de risco nutricional para DCNT, especialmente de obesidade central, confirmou a necessidade de ações de promoção de dieta saudável e saúde.

[Overweight and abdominal obesity in adults in aquilombocommunity in Bahia State, Brazil]

This study analyzes nutritional status, estimates the prevalence of overweight and abdominal obesity, and investigates factors associated with these outcomes in a two-stage random sample of adults (> 20 years) in quilombos (communities that descend from African slaves) in Vitória da Conquista, Bahia State, Brazil, in 2011. Among 739 participants, prevalence rates were 31.8% and 10.2% for overweight and obesity, respectively, and 55.7% for increased waist-to-height ratio (> 0.50). Prevalence of overweight was higher among 30-39-year-olds, while abdominal obesity was more frequent among older individuals. Female sex, eating chicken or beef with untrimmed fat, and hypertension were associated with higher odds of overweight and abdominal obesity, while smoking and single marital status were associated with lower odds. The results show high prevalence rates for overweight and abdominal obesity in these very poor and socially isolated communities. Specific preventive and control measures are urgently needed.

High degree of BMI misclassification of malnutrition among Swedish elderly population: Age-adjusted height estimation using knee height and demispan

BACKGROUND/OBJECTIVES

The degree of misclassification of obesity and undernutrition among elders owing to inaccurate height measurements is investigated using height predicted by knee height (KH) and demispan equations.

SUBJECTS/METHODS

Cross-sectional investigation was done among a random heterogeneous sample from five municipalities in Southern Sweden from a general population study 'Good Aging in Skåne' (GÅS). The sample comprised two groups: group 1 (KH) including 2839 GÅS baseline participants aged 60-93 years with a valid KH measurement and group 2 (demispan) including 2871 GÅS follow-up examination participants (1573 baseline; 1298 new), aged 60-99 years, with a valid demispan measurement. Participation rate was 80%. Height, weight, KH and demispan were measured. KH and demispan equations were formulated using linear regression analysis among participants aged 60-64 years as reference. Body mass index (BMI) was calculated in kg/m(2).

RESULTS

Undernutrition prevalences in men and women were 3.9 and 8.6% by KH, compared with 2.4 and 5.4% by standard BMI, and more pronounced for all women aged 85+ years (21% vs 11.3%). The corresponding value in women aged 85+ years by demispan was 16.5% vs 10% by standard BMI. Obesity prevalences in men and women were 17.5 and 14.6% by KH, compared with 19.0 and 20.03% by standard BMI. Values among women aged 85+ years were 3.7% vs 10.4% by KH and 6.5% vs 12.7% by demispan compared with the standard.

CONCLUSIONS

There is an age-related misclassification of undernutrition and obesity attributed to inaccurate height estimation among the elderly. This could affect the management of patients at true risk. We therefore propose using KH- and demispan-based formulae to address this issue.