PhilSPEN Online Journal of Parenteral and Enteral Nutrition

(Article 30 | POJ_0024.html) Issue January 2017 - June 2017: 141-153)

Original Clinical Investigation

Correlation of Bioelectric Impedance Analysis (BIA) and Different Nutritional Screening Tools (MNA, MAC, Calf diameter and BMI) among Geriatric Patients in a private tertiary care hospital in the Philippines

Abstract | Introduction | Methodology | Results | Discussion | Conclusion | References | PDF (134 KB) |Back to Articles Page

Submitted: July 5, 2007 | Posted: January 29, 2017


Bernard S. Balatbat, MD (1); Eliza Mei Francisco, MD (1); Milagros T. Barzaga, MD (2); Danilo C. Del Rosario, MD (1); and Catherine S. Carlos, MD (1)


  1. Clinical Nutrition Service, St. Luke’s Medical Center, E. Rodriguez Avenue, Quezon City, Philippines, 1102
  2. Institute of Geriatrics, St. Luke’s Medical Center, E. Rodriguez Avenue, Quezon City, Philippines, 1102


Background: Malnutrition is a common, often undiagnosed finding among patients in the hospital. Because of this, many nutritional screening tools have been formulated to aid in screening and diagnosing malnutrition among patients, particularly among the elderly. Some of these tools are, the BIA which measures the amount of the different compartments of the body, particularly fat percentage, and the MNA which is a validated nutrition screening tool for malnutrition among elderly persons. Does the BIA support the MNA together with the more common screening tools – BMI (Body Mass Index) and MAC (Mid Arm Circumference)?

Objective: This study aims to determine the correlation of BIA versus the MNA, MAC, BMI and Calf Circumference of geriatric day care patients at St. Luke’s Medical Center in January 2007.

Methodology: This is a cross-sectional study of all patients who were seen at the geriatric day care at St. Luke’s Medical Center in January 2007, and assessed using the BIA, MNA, MAC, BMI and Calf circumference screening tools. A Comprehensive Geriatric Assessment was conducted on each patient by the Geriatric Medicine Fellows. The BIA, MNA, MAC, BMI, Calf circumference scores of 101 patients included in the study were measured and recorded. Results were entered and analyzed. Correlation analysis was used with significant p value at P < 0.05.

Results: A total of 101 patients were admitted at the Geriatric Day Care. The correlation coefficient between BIA and BMI (0.487), between BIA and MAC (0.381) was 0.487 and 0.381 respectively, both with a P Value of < 0.001 which showed a significant correlation. Although the length of positive relationship is not high, the correlation between the BIA and BMI and MAC is significant (p<0.001. However, there appears to be no significant correlation between BIA against MNA and Calf Circumference, with a correlation coefficient of 0.019 with MNA and a P value of 0.85 and 0.137 with Calf Circumference and a P value of 0.73.

Conclusion: The BIA has a significant correlation with BMI and MAC and an apparent insignificant correlation with MNA and Calf Circumference.

KEYWORDS: BIA, BMI, MAC, MNA, correlation, body composition, assessment, nutrition, calf circumference



Malnutrition is a common finding in the elderly both in Hospitalized and OPD (Out Patient Department) patients. In one study carried out in 1976 a malnutrition level of 44% was reported in patients admitted to hospital (1). In another study performed in 1994 it was reported that 40% of patients admitted to hospital had malnutrition and that the nutritional status of 78% of these worsened during the period of hospitalization (2).

Estimations of the prevalence of malnutrition vary (20–78% in elderly medical patients) significantly in different studies because there are a variety of screening tools and cutoff values that can be used for anthropometric and biological assessment (3-7). No single indicator is able to set a definite finding of malnutrition alone, and various combinations of indicators have led to a range of different scales and indexes. Consequently, no single standard is currently the best for the assessment of malnutrition and related risk in the elderly. (3-7)

There are many tools that are being currently used for diagnosing malnutrition. Some of the screening tools that we are using in our institution are the following; BMI, BIA, MNA, MAC and Calf diameter.

BMI (Body Mass Index)
BMI remains to be one of the most reliable screening tools for malnutrition. In a study done by LaPorte, M., Villalon, L., & Payette, H. (2001), they were able to establish the sensitivity and the specificity of BIA and serum albumin as a very useful screening tool for malnutrition (8). They screened 160 subjects using BMI recruited from two settings. The sample included 54 adults in acute care, 57 elderly adults in acute care, and 49 elderly adults in long-term care. Comprehensive nutritional assessments including anthropometric data, biochemical test results, physical exam, and diet assessment were done to determine the validity of BMI as a screening tool.

The ESPEN guidelines also recommends the use of body mass index (BMI; in kg/m2) to reliably determine malnutrition (9, 10).

BMI was also used as a very reliable screening tool in a study done by Crogan, N.L., & Corbett, C.F. (2002). Wherein they described the prevalence of protein/calorie malnutrition among newly admitted elderly nursing home residents and identified the most significant predictors using Minimum Data Set (MDS) variables. (11)

MNA (Mini Nutritional Assessment)
The MNA is a simple, rapid, and reliable tool for assessing nutrition in the elderly and has rapidly become the screening tool of choice for many geriatric clinicians. (12)  It is frequently used in the nursing home setting and is composed of 18 items that require a professional to administer. It requires 10-15 minutes to complete and does not require laboratory tests. It consists of four sections: anthropometric, general, dietary, and self-assessment. The MNA was shown to be 98% accurate when compared with a comprehensive nutritional assessment which included food records and laboratory tests. (13)  Both the European Society of Parenteral and Enteral Nutrition (ESPEN) guidelines and the French Programme National Nutrition Santé (PNNS) recommend using the Mini Nutritional Assessment (MNA) to detect the risk of undernutrition among elderly subjects aged 70 y/o (14, 15). The MNA, which is based on a questionnaire, does not use biological indicators. It is more adapted to the elderly at home or in a nursing home setting than during hospitalization. In the nutritional status of elderly population mini nutritional assessment (MNA) is more convenient because it also evaluates the mobility and neurological and psychiatric condition of patients. MNA has been found to be more suited for elderly patients who are independent and capable of cooperation (16).

BIA (Bioelectric Impedance Analysis)
Bioelectrical impedance analysis (BIA) is a widely used method for estimating body composition. The technology is relatively simple, quick, and noninvasive. BIA is currently used in diverse settings, whether they are in patients or outpatients, and across a spectrum of ages, body weights, and disease states. The BIA is not limited to the measurement of body fat, but also measures muscle mass and water mass as well. BIA actually determines the electrical impedance of body tissues, which provides an estimate of total body water (TBW). Using values of TBW derived from BIA, one can then estimate fat-free mass (FFM) and body fat (adiposity). In addition to its use in estimating adiposity, BIA is beginning to be used in the estimation of body cell mass and TBW in a variety of clinical conditions. BIA measures the opposition of body tissues to the flow of a small (less than 1 mA) alternating current. Impedance is a function of two components (vectors): the resistance of the tissues themselves, and the additional opposition (reactance) due to the capacitance of membranes, tissue interfaces, and nonionic tissues. The measured resistance is approximately equivalent to that of muscle tissue (17).

Mid arm Circumference (MAC) and Calf Circumference (CC)
Arm circumference is a measure of the lean body mass in the arms, and it is used as a mean of quickly assessing the presence of acute malnutrition. Measuring MAC was very effective in rapidly diagnosing malnutrition especially among children in famine affected countries. (18) Although mid-arm circumference has been mainly used for nutritional assessment among children,(19, 20) it has been used in adults to assess dietary treatment with favorable results.(21) However, calf circumference has been recommended as a more sensitive measure of the loss of muscle mass in the elderly than arm circumference and mid-arm muscle area (22).  In a study made by Charlton KE, Kolbe-Alexander TL, Nel JH, it was studied that calf circumference is a better anthropometric measure since it documents the earliest indication of muscle wasting as ambulation is almost always the first to be compromised in the elderly patient as compared to the arms where there is usually continued use even after cessation of ambulation (23).

Objective of the Study
This is the objective of the study: To determine the correlation between BIA with the different nutritional screening tools (MNA, MAC, Calf diameter and BMI) of patients seen at the St. Luke’s Medical Center out-patient Geriatric Day Care Center.


This is a cross-sectional study of all patients who attended the geriatric day care at St. Luke’s Medical Center in January 2007. These are the Inclusion criteria: Day care attendees 60 years old and above, ambulatory. These are the exclusion criteria: Day care attendees who are diagnosed with cancer, history of diarrhea or dehydration for the past 3 days, amputee. These are the variables measured: anthropometric measurements – height in meters, weight in kilograms, mid arm circumference (MAC); general, dietary, and self assessments, lean body mass,  body fat and total body water. These are the tools used: Bioelectrical Impedance Analysis (BIA) and Mini-nutritional Assessment (MNA).

Subjects were informed of the study and its objectives. They were interviewed and assessed using the Mini-nutritional assessment form which include body mass index, mid arm circumference, calf-circumference as included in the anthropometric measurement. General assessment involves if the older person lives independently or in the nursing home, takes more than 3 prescriptions a day, if he or she has suffered psychological stress or acute disease in the past 3 months, mobility points, and neurological problems.

The MNA also includes inquiries on dietary and self assessments. MNA has a total score of 30. Less than 17 points is considered malnourished, 17-23.5 is at risk for malnutrition, and more than 24 points is considered well nourished.

Using a foot to foot BIA analyzer (Taylor), percentage of body fat and total body water are determined. The height of the patient is being measured and feed in the analyzer, as well as the age of the patient, weight, gender, and if the patient is an athlete or normal, then patient is instructed to set foot on the analyzer which displays the percentage fat of the body and the total body water.

Statistics: Sample size: 100 subjects; Statistical analysis: Correlation analysis; Significant p value < 0.05.


Table I. Tabulated means of the different diagnostic parameters (what are the value? cm? mm?)

Mean Age   


Mean BMI   


Mean BIA/fat percentage   


Mean MNA   


Mean MAC   


Mean Calf diameter   


Table I shows the means of the scores of the different parameters that was used on the patients/subjects. The mean age is 70 y/o. The BMI is 23.45 and the BIA/fat percentage is 29.77. The MNA, MAC and the Calf diameter is 26, 27 and 38 respectively. use only one decimal point

Table II.  Percentage and frequency distribution of the population

















Age Grouping




















Table II shows the total number of participants (101 patients), the frequency and percentage of the population according to gender and age grouping. The male group shows a frequency of 20 and a percentage of 19.8%. The female group shows a frequency and percentage of 81 and 80.1% respectively. According to age groupings, the 60 -69 y/o age group has a frequency and percentage of 37 and 36.6%; 70 – 79 age group has a frequency and percentage of 54 and 53.4%; and  the age group of 80 – 89 has a frequency and percentage of 10 and 9.9%;

Table III. Report on the effect of BIA vs. other parameters


Correlation coefficient

P value










BIA vs. Calf diameter



Not significant




Not significant

Table III shows the different association results of BIA fat percentage with the diagnostics parameters used in the study. The variables of BIA as compared to BMI shows a significant correlation with a correlation coefficient of 0.487 with a P value of <0.001. The variables of BIA as compared to MAC shows a significant correlation with a correlation coefficient of 0.381 with a P value of <0.001. However, the values for BIA versus Calf diameter failed to show a correlation with a correlation coefficient of -0.019 and a P value of 0.85. it is also the same with  BIA versus MNA which showed a correlation coefficient of 0.137 with a P value of 0.73.


The determination and meeting of patients’ nutritional requirements is a matter that falls within the physician’s professional responsibility. Every physician needs to be aware that nutritional support is at least as important as pharmacological treatment and that it will contribute to improvement in disease duration and the patient’s general performance, and needs to implement this in medical practice. In order to do this, a carefully obtained history should be done as it is one of the most valuable tools for identifying persons at risk for malnutrition. Nutritional assessment in an older person should involve taking a thorough history and physical examination in addition to anthropometric and biochemical measures.

Routine nutritional assessment of vulnerable elderly people is the first stage in implementing a nutritional program (24). In order to receive true assessments of nutritional status, it is important to pay attention to reliability and validity of the tool used (25). The purpose of nutritional assessments is to further establish baseline values, upon which the effectiveness of nutritional intervention could be measured against (26). Many different methods have been used to assess nutritional status in elderly people, based on objective nutritional assessments, routine history and physical examination, evaluation of dietary intake, and assessment tools (27). Presently however, there is no single gold standard being used for accurately determining malnutrition (28), which is probably due to the complexity of the phenomenon of nutritional problems in elderly people. Objective nutritional assessments, such as anthropometric measurements in combination with biochemical variables, are often used in nutritional assessments. The usual anthropometric measurement currently being used are body weight, Body Mass Index (BMI = weight in kg divided by height in m 2), as well as arm measurements, such as triceps skinfold thickness (TSF), midarm circumference (MAC) and midarm muscle circumference (29, 30, 31)

The physical examination should include determination of body’s general appearance, present body weight and height, and the presence of any sign of nutritional deficiency in the skin, hair, nail, eyes, mouth, or muscles. The body mass index (BMI) is a useful measurement for assessing nutritional status and can be calculated using the formula (BMI= Weight (kg)/ [height (m)] 2 ). The association between BMI and mortality in older adults follows a J-shaped curve, unlike the U-shaped curve relationship in younger adults(32,33)Data from several studies of elderly aged 60-90 years indicate the lowest mortality occurred at progressively increasing body weight(34) and higher mortality occurred with lower body weight(35) The desired BMI for older people is 24 to 29, compared with 20 to 24 in younger persons, and a measure below 24 is an indicator of malnutrition in older persons.(36) BMI, however, may not be as informative in the elderly as it is at younger ages. There is little documentation relating BMI to direct measurements of body composition in the elderly, especially at very old ages or in non-Caucasian ethnic groups. (36)

Other anthropometric methods include measurements of arm circumference, mid-arm muscle area, calf circumference, triceps skin-fold, and subscapular skin-fold thickness.

Historically, arm circumference has been used to assess nutritional status, due in part to its ease of measurement and its validity in children and younger adults. It is highly correlated with triceps skinfold and is recommended by some instead of using BMI for identifying low nutritional status (37). However, arm circumference reflects muscle mass poorly because movement of the arms in daily activities occurs until the very late stages of wasting, which helps to maintain the arm’s muscle mass. Thus arm circumference is a poor indicator of the decline in muscle mass in the remainder of the body, and its use as a possible indicator of wasting in hospital and intensive care settings has met with limited success. Alternatively, calf circumference is recommended as a better descriptor of overall muscle mass because the legs contain over half of the muscle mass of the body. (22) The reason is that one of the first things that happens during wasting or undernutrition is reduced walking which brings about the cascade of reduced mobility, loss of weight and fat-free mass, leading to increased morbidity and subsequent mortality. (37)

The Mini-Nutritional Assessment (MNA) is widely used as a screening tool for malnutrition. It is practical, noninvasive and cost-effective tool which allows a rapid nutritional evaluation and effective intervention in the elderly. (38) In a study done in a Geriatric Tertiary Care Hospital in Switzerland, the Mini-Nutritional Assessment (MNA) tool was used for validation in the assessment of the nutritional status in older people on admission. They evaluated 1319 patients (mean age 84.2), 70% of whom were women admitted between February 1996 and January 1998. The analysis includes the 1145 of this group who had a complete MNA admission. This represented 24% of the 4677 admissions to the hospital during the study period. The MNA scores averaged 19.9 (3.8 mean SD) with a range of 8.0 ± 27.5. Patients in the groups with and without an available completed MNA were similar in terms of sex distribution and age. These results were comparable with the local study conducted by the investigators. (39)

BIA has been validated for the assessment of body composition and nutritional status in various patient populations, including cancer patients (40-44). The national institutes of health and technology assessment conference statements states that the value of BIA in the estimation of body adiposity both on a clini­cal basis in the individual and epidemiologically in large groups to define the presence or prevalence of obesity, respectively, is of great interest. BIA is a more accurate measure of FFM and percentage of body fat than body weight, height, or body mass index, and at little extra cost or difficulty but with somewhat greater complexity. BIA may pro­vide a more accurate measure of adiposity than do skin-fold measure­ments and may be more easily standardized, although measurements of skin folds and girths may provide additional useful information on body fat patterning. (45) And in cases during nutrition monitoring of refeeding syndrome patients, BIA could predict changes in body composition with significantly greater precision than anthropometry alone. (44)

In our study however, the results showed that only BMI and MAC showed a significant correlation with BIA. This is in spite of the fact that both BIA and MNA has been fully established and verified as a reliable screening tool for the diagnosis of malnutrition. The fact that the values of MAC, BMI and Calf circumference are actually part of MNA seems to offer conflicting conclusions. Thus it can be considered that MNA is more of a clinical assessment rather than a tool for determining body composition screning for malnutrition of the elderly.


The good correlation of BIA with MAC and BMI showed that these two anthropometric tools are of value in assessing the body composition of the patient. MNA did not show a significant correlation indicating that this may be more important as a clinical assessment rather than a nutritional and body composition analysis tool.



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Abstract | Introduction | Methodology | Results | Discussion | References | Back to Articles Page