Nutritional Assessment

Nutritional assessment is a prerequisite for provision of appropriate nutritional support in patients with TB, and on follow-up of the patient. Nutritional assessment may vary according to the population groups, e.g. adult patients (above 18 years), children and adolescents (6–18 years), children under 5 years of age, and pregnant mothers.
General Nutritional assessment will include the following:
1. Clinical assessment: This includes a nutrition-oriented history and a nutrition-oriented examination
2. Anthropometric assessment
3. Dietary assessment and laboratory assessment wherever feasible and appropriate.
Assessment at diagnosis
It is important to identify undernutrition at the onset of diagnosis and and establish the baseline of nutritional indicators to monitor the response to treatment in patients with TB. It is also important to identify children and adults who may be severely undernourished, with or without other complications and who may require initial treatment in a hospital.
Assessment at follow up
In patients who continue to be moderate- severely undernourished during follow-up, further risk factor and dietary assessment will be necessary, as follows:
- Poor TB treatment adherence and/or response, resistance to TB drugs
- Clinical assessment for other non-dietary causes of malnutrition, including identification of important co-morbidities such as diabetes, HIV, alcohol
abuse.
- Biochemical assessment whenever possible
- Dietary assessment, including assessment of food security.
Weight loss or failure to regain or maintain a healthy weight, at any stage of disease should trigger further assessment and appropriate interventions. Nutritional status of patients with MDR-TB is particularly important as treatment outcomes in this group of patients are sub-optimal and poor nutritional status has been associated with greater frequency of side-effects, delayed time to sputum conversion, and mortality.

Nutritional assessment of adult patients
Clinical assessment

Nutrition oriented history relevant for all TB patients is given in Table 1

Table 1: Nutrition oriented history in patients with active TB

*Please check if the patient is eligible for any national or state-level scheme for nutritional /social support. Check for BPL status or membership of ESIC scheme, or eligibility for Antyodaya Anna Yojana. Young children, pregnant and lactating mothers are eligible for benefits under ICDS. Many states support TB patients financially (A list of schemes is available in annexure 10 of Guidance document nutritional care and support for TB patients in India)

Macronutrient deficiencies

Micronutrient defeciencies

Anthropometric assessment
Height and weight: The methods for height and weight measurement are as indicated in annexure 3. The equipment for this measurement should be calibrated and maintained. Body Mass Index (BMI): This is a measure of weight adjusted for height, which is calculated by dividing the weight in kg by the square of height in metres.
BMI= 𝑊𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑘𝑔/ (𝐻𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑚)²
BMI is useful as a measure of the fat and muscle mass of the body. It is also useful as an indicator of risk of morbidity and mortality, which increase linearly in subjects with both BMI higher and lower than normal. At higher BMI, the risk of CVD deaths increases, while at lower BMI subjects are at greater risk of dying due to respiratory causes including TB.

Table 2: Classification of nutritional status and associated risk using BMI as criteria

*A WHO expert consultation in 2004 proposed different cut-offs for overweight and obesity in Asians on the basis of available data which suggests that Asians have a higher percentage of body fat than White people of same age, sex and BMI. The consultation identified potential action points: Underweight BMI less than 18.5; Normal- BMI 18.5-22.9; Overweight- BMI 23.0-26.9; Obesity-BMI> 27.0. 

# Situation not likely to be common in case of TB patients.
Body mass index is not accurate for estimation of nutritional status in those with oedema (e.g. due to hypoalbuminemia) and for pregnant women. In these situations, the mid-upper circumference may be used for nutritional assessment. The cut-off of BMI <16 kg/m² is used to define severe undernutrition, and a WHO guideline recommends admission of all patients with BMI < 16 kg/m². However, in a cohort of rural patients with pulmonary TB in India, nearly half of the patients had a BMI<16 kg/m² and it may not be feasible to admit all such patients in an inpatient facility. In the same cohort the median BMI of both male and female patients at death was around 14 kg/m², and therefore this level has been suggested as an absolute criterion for admission for initial nutritional support.
Mid upper arm circumference (MUAC)
MUAC is the circumference of the left upper arm -measured midway between the tip of the shoulder (acromion) and elbow (olecranon). It is an indicator of nutritional status (including fat and protein stores), and like the BMI is also independent of height. It can be measured in pregnant women and those who are unable to stand.
MUAC <23 cm in Men and < 22 cm in women correlates with a BMI of < 18.5 kg/m² and is suggestive of undernutrition. MUAC reflects of the effect of acute undernutrition more than BMI, and has been seen to an independent predictor of mortality in both HIV positive and HIV negative individuals. Patients with a MUAC less than 19 cm had 5 times the mortality rate of those with a MUAC > 24 cm.
The method for measurement is as indicated in annexure 3.
There are no standard MUAC cut-offs for different grades of adult undernutrition. In WHO Integrated management of Adolescent and Adult illness, a cut-off of MUAC < 16 cm was used to define severe undernutrition. However, a cut off of less than 16 cm would correspond to a situation of virtually no peripheral energy stores, and excess mortality has been seen at levels of MUAC which are higher than this cut-off in patients with active TB. It may be therefore prudent to have a higher cut-off of MUAC as suggested in recent guidelines, and some national protocols for management of severe acute malnutrition in adults.
The guidance document therefore proposes the following criteria for initiation of nutritional support in an inpatient setting for adults (>18 years):

Biochemical and laboratory evaluation including HIV testing

Hemoglobin: Anemia due to deficiency of micronutrients like iron and folates is very common in patients with TB and can contribute to poor performance status in patients with TB. It can be assessed at PHC/CHC levels using available methods.

Criteria to classify anemia in males and females (WHO)

Table 3: Criteria to classify anemia in males and females (WHO)

Serum albumin is affected by malnutrition but is also affected by inflammation. The normal range is 3.5 to 5.5 g/dL. In patients with TB, hypoalbuminemia (e.g. serum albumin less than 2.7 g/dl) has been associated with increased risk of death, while a higher albumin was inversely related to treatment failure in patients with extensively drug resistant TB. 

HIV testing should be considered in adults with severe wasting as outlined in the box below.

Serum electrolytes: Measurement of serum potassium and magnesium is desirable, if patient has severe undernutrition and has been admitted for inpatient management. This is because patients with severe undernutrition are deficient in these, and low levels of potassium and magnesium are risk factors for re-feeding syndrome 

• Nutritional assessment of children and adolescents
  This covers the 6–18 year age group. History and examination in terms of clinical assessment are the same as in adults. The presence of bilateral oedema should be noted. For anthropometric assessment, height and weight to be measured as indicated in annexure 3. In children between 6 and 18 years the classification of malnutrition can be based on the BMI-for-age percentile charts for girls and boys. Simplified field tables or percentile based charts can be used for classifying the nutritional status of the patient (Annexure 4). The MUAC can be also used to define acute malnutrition and the cut-offs suggested are at Table 4

  Nutritional indicator	Age group	Severe acute malnutrition (SAM)	Moderate acute malnutrition (MAM)
  BMI for age	6 years to less than 18 years	Less than -3 z score (< -3 z score)	>-3 z score to < - 2 z score
  MUAC	6 years to less than 10 years	Less than 11.5 cm (<11.5 cm)	>13.5-14.5 cm
  	10 years to less than 18 years	Less than 16.0 cm (<16.0 cm)	≥16.0 &< 19.0 cm
  Oedema	6 years -18 years	Present	Absent

Table 4: Anthropometric measurements and classification in children 6–18 years of age

For biochemical assessment the cut-offs for anemia are given in Table 5

Table 5: Cut offs for diagnosis and classification of anemia in children 5–18 years of age

Nutritional assessment of under-5 patients
1) Clinical assessment: History and examination
2) Documentation of social assistance schemes patient is already entitled to/
3) Anthropometric assessment

• Weight for length (0-1 year of age)
• 1-5 years: WHO growth charts, weight for age for boys and girls (annexure 4)

4) Biochemical assessment
5) Basic dietary assessment as informed by mother.
 

Nutritional assessment of pregnant women
The clinical assessment remains same with added information about
- last menstrual date and trimester
- pre-pregnancy weight if available
- clinical assessment to rule out high risk pregnancy or pregnancy with complication
- routine antenatal care and advise
For first trimester BMI can be used for nutritional assessment. Throughout pregnancy, weight gain should be recorded during each visit and mother should be asked to come with her Mother and Child Protection card to the DOTS center. During second and third trimester, MUAC can be used for classifying nutritional status. During pregnancy the suggested MUAC cutoff for severe malnutrition is <22 cm. Cut-offs for anemia are as indicated in table 3.

Resources

• Guidance document nutritional care and support for TB patients in India

Assessment