World Vision International
article • Tuesday, October 23rd 2012

Anaemia Assessment Guidance

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PURPOSE OF THIS GUIDE

This guide introduces the Hemocue and describes how it can be used to assess anaemia levels at the field level.

 

WHO SHOULD USE THIS GUIDE?

This guide should be used by technical staff and design, monitoring and evaluation (DME) staff to help them identify whether using the Hemocue machine is a feasible and useful method for assessing anaemia in their target populations.

 

WHAT IS A HEMOCUE?

A Hemocue is a portable field-friendly tool that measures haemoglobin in capillary blood samples.

 

Background on Anaemia

Anaemia is the condition of low levels of haemoglobin in the blood. This results in a reduced amount of oxygen being transported in the body. Iron is a main component of haemoglobin and iron deficiency is estimated to be responsible for over half of all anaemia globally. Other causes of anaemia include malaria, hookworm and other helminthes; other nutritional deficiencies such as vitamin A, vitamin B12 or folic acid deficiency; chronic infections; genetic conditions which vary by region (such as sickle cell and thalassemia); HIV/AIDS; and high fertility. Anaemia is a serious concern for pregnant women and children. It increases the risk of maternal mortality and poor birth outcomes. In children anaemia impairs cognitive development, stunts growth and increases morbidity from infectious diseases. It is estimated that more than two billion people globally, mostly women and children, are anaemic. Anaemia is considered a public health problem when more than 5% of the intended population is anaemic, a significant public health problem in need of immediate action when prevalence exceeds 20%, and a severe public health problem when prevalence exceeds 40% (WHO/UNICEF/UNU 2001. Iron deficiency anaemia: Assessment, prevention and control. A guide for programme managers).

Prevalence

Public Health Significance

> 40%

Severe

20-39%

Moderate

5-20%

Mild

0-5%

Normal

Source: WHO/UNICEF/UNU. Iron deficiency anaemia: assessment, prevention, and control. Geneva: World Health Organization; 2001. (WHO/NHD/01.3).

 

Information on the prevalence of anaemia can be useful for the development of health-intervention programmes designed to prevent anaemia, such as promoting consumption of iron-rich foods, iron supplementation, food fortification, malaria prevention and treatment, and deworming programmes as appropriate. 

Haemoglobin is a commonly used, well validated, and widely accepted indicator for anaemia. Mean haemoglobin is one useful way to present this indicator. However, anaemia is also commonly presented based on cutoffs. The following haemoglobin cutoffs are used to classify anaemia severity.

 

Anaemia is the condition of low levels of haemoglobin in the blood. This results in a reduced amount of oxygen being transported in the body. Iron is a main component of haemoglobin and iron deficiency is estimated to be responsible for over half of all anaemia globally. Other causes of anaemia include malaria, hookworm and other helminthes; other nutritional deficiencies such as vitamin A, vitamin B12 or folic acid deficiency; chronic infections; genetic conditions which vary by region (such as sickle cell and thalassemia); HIV/AIDS; and high fertility. Anaemia is a serious concern for pregnant women and children. It increases the risk of maternal mortality and poor birth outcomes. In children anaemia impairs cognitive development, stunts growth and increases morbidity from infectious diseases. It is estimated that more than two billion people globally, mostly women and children, are anaemic. Anaemia is considered a public health problem when more than 5% of the intended population is anaemic, a significant public health problem in need of immediate action when prevalence exceeds 20%, and a severe public health problem when prevalence exceeds 40% (WHO/UNICEF/UNU 2001. Iron deficiency anaemia: Assessment, prevention and control. A guide for programme managers).

Prevalence

Public Health Significance

> 40%

Severe

20-39%

Moderate

5-20%

Mild

0-5%

Normal

Source: WHO/UNICEF/UNU. Iron deficiency anaemia: assessment, prevention, and control. Geneva: World Health Organization; 2001. (WHO/NHD/01.3).

Information on the prevalence of anaemia can be useful for the development of health-intervention programmes designed to prevent anaemia, such as promoting consumption of iron-rich foods, iron supplementation, food fortification, malaria prevention and treatment, and deworming programmes as appropriate.

Haemoglobin is a commonly used, well validated, and widely accepted indicator for anaemia. Mean haemoglobin is one useful way to present this indicator. However, anaemia is also commonly presented based on cutoffs. The following haemoglobin cutoffs are used to classify anaemia severity.

 

Non pregnant women of reproductive age 15-49 years

Pregnant women

Children 6 months to 5 years

Non-anaemic

≥12 g/dL

≥11 g/dL

≥11 g/dL

Mild anaemia

10-11.9 g/dL

10-10.9 g/dL

10-10.9 g/dL

Moderate anaemia

7-9.9 g/dL

7-9.9 g/dL

7-9.9 g/dL

Severe anaemia

<7 g/dL

<7 g/dL

<7 g/dL

Source: WHO/UNICEF/UNU. Iron deficiency anaemia: assessment, prevention, and control. Geneva: World Health Organization; 2001. (WHO/NHD/01.3).

 

Haematocrit is also commonly used as an indicator of anemia. Haematocrit and haemoglobin are interchangeable using the following conversion factors (100g haemoglobin = 6.2 mmol haemoglobin = 0.20 l/l WHO 2001). Cutoffs for anaemia using haematocrit are provided in the table below:

 
Age / gender group
Haematocrit
 
Nmol/L
l/L
Children 6-59 months
6.83
0.33
Non-pregnant women of reproductive age (15-49 years)
7.45
0.34
Pregnant women
6.83
0.36
Men (>15 years)
8.07
0.39
 

Because anaemia has many potential causes, neither haemoglobin nor haemotocrit are indicators of iron deficiency per se. Iron deficiency is measured using serum ferritin which requires techniques and laboratories often beyond the capacity of programme areas. Guidance is provided later in this document for determining whether iron deficiency may be a problem when only anaemia data is available.

In many instances it is sufficient to document the prevalence of anaemia as the total proportion with haemoglobin < 11 g/dL or haematocrit <0.36 l/l with no further classification according to severity. However, in areas where there is a high prevalence of severe anaemia it may be important to further classify anaemia according to severity. In these areas it will be difficult to improve haemoglobin to the extent that severely or even moderately anaemic women or children become non-anaemic. It is more likely that a decrease in severe anaemia will be seen, but there will be increases in moderate or mild anaemia. The proportion of the target population who are not anaemic however may not change. Thus in the context of a high prevalence of severe anaemia, using severity classifications may be useful for measuring change in anaemia status.

For smokers and populations living at high altitudes, adjustments to individual haemoglobin measurements must be made to properly determine anaemia. These adjustments can be found at the end of this guidance document. Therefore endline and baseline questionnaires that intend to include haemoglobin assessment of adult populations should include questions related to smoking habits including whether the respondent smokes, what type of smoking (cigarette, bidis, pipe, etc.), and how many per day. Area Development Programmes (ADPs) at high altitudes (<1000 feet) should attempt to determine their altitude. Information on altitude can usually be obtained from the Ministries that deal with use of land or natural resources, for example the Ministries of Agriculture, Forests and Soil Conservation, National Parks and Recreation or other similar ministries.

 

SHOULD I USE HEMOCUE FOR COLLECTING DATA?

Programme managers should consider collecting information on anaemia when:

  1. They are in the planning stages of a project and / or are conducting an assessment of the current health problems in their programme area, especially if it is believed that anaemia is a public health problem in the community as this may inform the type of activities needed in the programme area. It is often possible to obtain information on anaemia for this purpose by using existing data (see next section).
  2. Programmes have significant levels of anaemia at baseline and indicate reductions in anaemia, either overall or in severity, as a primary outcome of the project. In these instances it may be useful to include anaemia assessment as part of your project’s DME framework. This may require the use of field methods for measuring indicators of anaemia.
 

HOW DO I COLLECT DATA ON ANAEMIA?

Existing Data: There are ways to obtain data on the prevalence of anaemia and/or iron deficiency in your target population and project area without conducting additional surveys. The WHO database on micronutrient deficiencies is available on the internet and provides data at the country and in some cases regional/provincial level on anaemia and iron deficiency (http://www.who.int/vmnis/database/en/). If this database is not accessible, then the Ministry of Health and/or the WHO and UNICEF country offices are other sources of information on the prevalence of anaemia and iron deficiency. Demographic Health Surveys (http://www.measuredhs.com/countries/) also periodically conduct anaemia prevalence surveys and may have data on the prevalence of anaemia among pregnant women and/or women of reproductive age in the country and possible region of interest. As well local universities and colleges that have health or nutrition degree courses may have prevalence data or other information on anaemia in the project area. Data collected from other sources will be useful to help you determine whether anaemia is a potential public health problem in your project area.

Field Surveys with Hemocue or Haematocrit: You may also conduct a field survey to find out the prevalence of anaemia in your project population either as part of an initial assessment or as part of your MLE framework. This can be done by measuring haemoglobin with the Hemocue machine. The Hemocue is recommended by WHO when the measurement of haemoglobin is to be conducted in the field, i.e. as part of field surveys. The Hemocue is a fast, portable, valid, accurate and easy to use biological for anaemia. The analysis requires a minimal amount of blood collected by finger prick. The capillary sample may be collected, analysed in the home and results made available immediately to the participant. It is uniquely suited for rapid field surveys because the one-step blood collection does not require liquid re-agents. It is used by the United States Centers for Disease Control (CDC) in their National Health and Nutrition Examination Surveys (NHANES) as well as by Demographic and Health Survey teams on many countries around the world to assess anaemia. Non-laboratory people can be trained to operate the device and it is not dependent on electricity. However, context may determine who is allowed to collect capillary samples and use the Hemocue. 

Other indicators of anaemia: In some cases, haemoglobin assessment by Hemocue may be beyond the scope of the ADP due to costs or other logistical reasons or may be outside the primary objectives of the project. In these instances, ADPs may opt to use facility level data as the primary source of data on anaemia prevalence at baseline and endline. Health facilities are often capable of measuring haematocrit. However, facility-based estimates from haematocrits may overestimate the prevalence of anaemia in a project area because only sicker community members may present for care at the facility and these individuals may be more likely to have anaemia. Therefore, the field team should collect samples from respondents and then analyse them at the health facility instead of relying solely on the haematocrits of those who come to the health facility.

 

WHO ARE MY POPULATIONS OF INTEREST?

In general, women of childbearing age (15-49) including pregnant women and children under five years of age are the usual target populations of interest. However, the population of interest will be determined by the programme interventions and objectives. For example, the 7-11 strategy aims to reduce anaemia in pregnant women and young children. In this instance pregnant women and children 6-24 months of age will be the target population. In some instances, girls aged 11-14 may be the intended population if the project aims to improve anaemia status before girls reach childbearing age or if early age at marriage or first birth is common in the community. Infants younger than six months are not usually included in anaemia surveys because they are not considered at risk for anaemia and/or iron deficiency unless they are born low birth weight and because of the difficulty in collecting adequate capillary samples from finger/heel prick.

 

WHAT SAMPLE SIZE IS NEEDED TO ESTIMATE ANAEMIA PREVALENCE USING HAEMOGLOBIN FOR A FIELD SURVEY?

To determine the prevalence of anaemia in your target population using haemoglobin, Berger and Pierre-Louis (2002) recommend a sample size of 450 subjects per target group using a cluster sampling approach with 30 communities sampled per survey area (30 communities and 15 participants from each target group in each community). The sample size can be approximated by the following formula for population sizes greater than 10,000:

n = z2pq/d2

where n is the desired sample size; z is 1.96, which corresponds to the 95% confidence level; p is the estimated prevalence of anaemia, set at 50%; q is 1-p; and d is the desired degree of accuracy, set at 0.05. The result is 384. This is increased somewhat to account for the design effect of cluster sampling. It should be noted that the higher the anticipated prevalence of anaemia in the population of interest the smaller the sample size needed and vice versa. Programme managers can obtain estimates of the anticipated prevalence from previous assessments in the area, for example from regional level data provided by Demographic and Health Surveys, from the WHO micronutrient database, or the Ministry of Health. If data does not exist then it is recommended that programme managers use an anticipated prevalence of 50%.

A free software called sampleXS is available for download to help with sample size calculations for surveys (http://www.healthcarefreeware.com/calc.htm). You enter the total size of the target population in the survey area, the design effect (usually estimated at 2), the anticipated prevalence from previous research, and an estimate of the acceptable error rate (precision, typically 5%) and it calculates the necessary sample size. Then divide that by 30 to obtain the number of children per cluster. The total population size does not have to be exact but is needed to apply an adjustment factor if your sample is less than 5,000.

 

WHAT SUPPLIES DO I NEED?

A list of supplies needed to measure haemoglobin using the Hemocue and sources for these supplies are provided in Appendix 2 at the end of this guidance document. Survey managers should determine:

  1. the number of field teams that are needed to adequately cover the estimate sample size,
  2. the additional supplies needed for each team to measure haemoglobin using the Hemocue , and
  3. the costs of training field teams and implementation.
 

WHAT ARE THE STEPS INVOLVED IN MEASURING HAEMOGLOBIN WITH THE HEMOCUE?

Below are the basic steps involved in measuring haemoglobin using the Hemocue. More detailed steps on the calibration and maintenance of the Hemocue and how to appropriately and safely conduct the finger prick, collect capillary samples and dispose of materials are provided in the guide by Berger and Pierre-Louis referenced at the end of this guidance document. 

  1. At the beginning of each work day, standardise the Hemocue machine using the Hemocue control cuvette according to the manufacturer’s instructions (if necessary, depending on model used); assemble all needed supplies. All field workers should remove all rings and bracelets, wash hands thoroughly with soap and water and cover any cuts with Band-Aids.
  2. At the field site, when it is time to do the Hemocue analysis, collect informed consent from each participant for the procedure. If the participant refuses to do the analysis, note this on the questionnaire as a refusal. If the participant agrees, then proceed with the analysis.
  3. Wear gloves and use only new, unopened materials for each participant. Using appropriate techniques and hygiene, clean the finger and perform the finger prick to collect the capillary blood sample using standardised and hygienic techniques.
  4. Using the appropriate techniques, collect the capillary blood sample into a Hemocue microcuvette.
  5. Insert the microcuvette into the Hemocue machine and obtain haemoglobin reading. Record the Hemocue reading on the questionnaire.
  6. Clean and bandage the participant’s finger, disinfect surfaces and carefully dispose of all gloves, needles/lancets and other contaminated materials in a special container designated for these items. Do not dispose of any materials at the field site.
  7. For the next subject you will use a new set of materials.
  8. At the end of each day, clean the Hemocue machine according the model’s specifications.
 

HOW MUCH DOES IT COST?

The costs associated with Hemocue use can be high. Below is a breakdown of costs commonly associated with using the Hemocue. As prices may change over time it is recommended to consult with suppliers on exact costs. A list of supplies is provided at the end of this guidance document. It is recommended to have one Hemocue and case per team. The cost for every 100 persons sampled is provided below. The cost per person per sample for just the basic Hemocue materials is approximately $2.40 USD. This estimate does not include the cost of the Hemocue machines themselves or additional field supplies, such as biohazard containers, bandaids, cleaning pads, etc., as these may be different in different programme settings.

 
 
 
Unit Cost (USD)
Per 100 persons sampled (USD)
Hemocue and case
750
-
Package of 200 Microcuvettes
260
130
Pack of 14 Hemocue cleaner swabs
15
15
Package of 200 Safety lancets
130
65
Package of 100 disposable, non sterile gloves
15
30
Total excluding machine per 100 sampled
-
240
 

 

 

CONSIDERATIONS AND PRECAUTIONS FOR MEASURING HAEMOGLOBIN USING THE HEMOCUE

Using the Hemocue to measure haemoglobin places field teams in potential contact with blood. Therefore all team members must be trained on how to safely use the Hemocue and appropriately dispose of all materials. Further appropriate infection control techniques must be enforced to prevent contamination of participants, for example field team members must always use a new pair of gloves with each participant, never reuse lancets or microcuvettes, and immediately and appropriately dispose of all materials that come into contact with blood or the participant (i.e. lancets, gloves, gauze, microcuvettes) in designated containers.

A potential source of error in measuring haemoglobin is using inappropriate techniques to collect the capillary blood sample. Inappropriate techniques can cause contamination of the blood sample or early blood clotting or blood cell damage which may result in inaccurate results. Care must be taken to ensure adequate puncture of the skin and spontaneous blood flow from the puncture site. The key to accuracy is appropriate blood sampling from finger- or heel-prick. The Hemocue guide by Burger and Pierre-Louis referenced earlier in this document provides step-by-step instructions to appropriately collect capillary blood samples to reduce error. 

Because Hemocue use involves handling a biological sample and is minimally invasive, haemoglobin assessed by Hemocue may be regulated by the government such that only certified individuals (i.e. lab technicians, nurses, doctors) can perform the tests. It may require approvals at the community, regional or national level. Infection control precautions must be taken including proper hand cleaning, the use of disposable/single use gloves, lancets, and microcuvettes, proper disposal of these items, and proper disinfecting of surfaces and equipment. Always check with your MOH, WHO or UNICEF office regarding any regulations on use of Hemocues in your project area. Regardless of the level of approvals required by the area of study, in all cases you must get permission (informed consent) from participants before proceeding with blood sample collection and Hemocue analysis. 

Due to cost of the Hemocue machines and microcuvettes, haemoglobin measured using the Hemocue may not be an appropriate indicator for regular monitoring. However baseline and endline measures in programme communities are recommended to assess the contribution of a programme to reductions in anaemia. Additionally the relatively high cost limits its use in routine clinical services in primary health facilities. However haemoglobin measured with the Hemocue can be used for quality assurance comparison with other haemoglobin methods used by primary health facilities.

It should be noted that the concerns and considerations specified above are also present if field teams are collecting blood samples for haematocrit analysis. Though the use of haematocrits collected in the field has similar costs as the Hemocue in terms of disposable materials (lancets, gloves, tubes, etc.) this indicator requires larger sample sizes and may carry additional considerations such as the proper storage and transport of samples to facilities for analysis.

 

WHAT IS NOT ADDRESSED IN THIS GUIDE

This guide is not intended to be a field guide for training field teams on the use of the Hemocue, planning anaemia surveys, or implementing such surveys in the field. While these topics are briefly introduced, for a detailed step-by-step field guide that addresses these items, the reader is referred to the 2002 manual by Burger and Pierre-Louis “How to assess iron deficiency anaemia and use the Hemocue”. This tool is available online at http://pdf.usaid.gov/pdf_docs/PNACW824.pdf. The 2001 World Health Organization (WHO) publication “Iron Deficiency Anaemia: Assessment, Prevention and Control. A guide for Program Managers” provides additional details on anaemia, iron deficiency and their assessment in populations. This tool is available online at http://www.who.int/nutrition/.../ida_assessment_prevention_control.pdf 

This guide focuses on the use of haemoglobin as a core indicator for anaemia and its measurement in the field. Currently the measurement of haemoglobin using the Hemocue machine is one of only two methods recommended by WHO for assessing anaemia using haemoglobin (WHO 2001). The other method, the cyanmethemoglobin method, must be done in a laboratory and therefore is not addressed in this document. Haematocrit is also a commonly used biological indicator to assess anaemia. It is the volume of packed red blood cells as a portion of the total volume of blood and is measured and expressed as nmol/L or l/l of whole blood. The WHO also views haematocrit as an acceptable and recommended biological indicator for anaemia. For haematocrit determination, blood is collected in anticoagulant-treated capillary tubes and spun in a specially designed centrifuge. Because the method for determining haematocrit is less relevant for field teams, it is not discussed extensively in this document though distinctions are made between it and haemoglobin when this information may be useful.

Additional methods exist for assessing anaemia in the laboratory or in the field that are not addressed in this guidance document. For example, a common field tool for assessing anaemia is the presence of physical signs. However the use of physical signs is only valid for identifying severe anaemia and is not recommended for detecting moderate and mild anaemia due to low sensitivity and specificity. For more information on alternative anaemia measurements we refer the reader to the WHO guide “Iron Deficiency Anaemia: Assessment, Prevention and Control. A Guide for Program Managers” available online athttp://www.who.int/nutrition/.../ida_assessment_prevention_control.pdf

We understand that programmes differ in regards to capacities, objectives, context and resources. For this reason we encourage the programme manager to consult with the World Vision Nutrition Centre of Expertise to determine the best measurement method based on the programme’s context, objectives and capacity.

 

ADDITIONAL RESOURCES

Anemia Prevention and Control: What Works? Part II Tools and Resources. Monitoring, Evaluation, and Design Support (MEDS) project; USAID. Available athttp://pdf.usaid.gov/pdf_docs/PNACU946.pdf
Berger and Pierre-Louis. 2002. How to assess iron deficiency anemia and use the Hemocue. Helen Keller International and USAID. Available athttp://pdf.usaid.gov/pdf_docs/PNACW824.pdf
WHO/UNICEF/UNU. 2001. Iron Deficiency Anaemia: Assessment, Prevention, and Control. A guide for programme managers. Available athttp://www.who.int/nutrition/publications/en/ida_assessment_prevention_control.pdf

 

APPENDIX 1: ADJUSTMENTS TO INDIVIDUAL HAEMOBLOBIN BASED ON ALTITUDE AND SMOKING

 

Altitude (m)
Adjustment (g/dL)
< 1000
No adjustment
≥1000, <1250
-0.2
≥1250, <1750
-0.5
≥1750, >2250 
-0.8
≥2250, <2750 
-1.3
≥2750, <3250 
-1.9
≥3250, <3750 
-2.7
≥3750, <4250 
-3.5
≥4250, <4750
-4.5
≥4750, <5250
-5.5
≥5250
-6.7
Cigarettes smoked per day
< 10
No adjustment
10–19 per day
–0.3
20–39 per day
–0.5
40 or more per day
–0.7
Unknown quantity or non-cigarette smoking (i.e. pipes, bidis)
–0.3
 

APPENDIX 2: DETAILED LIST OF SUPPLIES NEEDED TO CONDUCT HAEMOGLOBIN MEASUREMENT USING HEMOCUE

Necessary Supplies
Number per unit
HemoCue Machine + case
1 per survey team
Shoulder bag or back pack to carry equipment and supplies
1 per survey team
 New or recharged AA batteries (5 + 5 backup)
10 per survey team
Control microcuvette that matches the serial number of the HemoCue machine
1 per survey team
Quality Assurance Logbook
1 per survey team
Bottle of alcohol
1 per survey team
Disinfectant: Lysol spray or bleach 1 survey team
1 per survey team
Roll of paper towels to disinfect the worktable
1 per survey team
Soap, basin, and cup for hand washing or large bottle of hand sanitizer
1 per survey team
Plastic sheet to drape over work surface (paper towels can be used if the table is made of metal or plastic that can be cleaned with disinfectant)
1 per survey team
Tacks or tape to secure plastic sheet 1 survey team
1 per survey team
Hard plastic Sharps Biohazard container to dispose of lancets and microcuvettes
1 per survey team
Container lined with a plastic bag for items contaminated with blood
1 per survey team
Pens
2 survey team
Clipboard for writing down responses to the questionnaire
1 per survey team
Sturdy folder to protect questionnaires
1 per survey team
Questionnaires (see WV 7-11 site for example anaemia survey questions)
1 per survey subjects+10%
Microcuvettes
1 per blood sample+5% for errors
Disposable sterile lancets
1 per blood sample +5% for errors
Band-Aids
1 per blood sample
Disposable (non-sterile) latex gloves
2 per blood sample
Gauze pads 5 cm x 5 cm (2 in x 2 in)
3 per blood sample
Depending on location of sample collection
 
Chairs for survey workers and the subject
2-3 per survey team
A thick cloth or mat for survey subjects to lie down if they feel faint
 
Lightweight portable worktable. An additional table for notebooks and supplies is desirable
1 per survey team
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