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AFHSC Surveillance Case Definitions
Case Definition and Incidence Rules
For surveillance purposes, a case of iron deficiency anemia is defined as:
One hospitalization with any of the defining diagnoses of iron deficiency anemia (see ICD9 and ICD10 code lists below) in the first or second diagnostic position; or
Two outpatient medical encounters, occurring within a 365-day period , with any of the defining diagnoses of iron deficiency anemia (see ICD9 and ICD10 code lists below) in the first or second diagnostic position; or
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Exclusions:
None
ANEMIA; IRON DEFICIENCY
Does Not Include Pregnancy-Related Anemia; Includes Case Identification Criteria for
Recurrent Iron Deficiency Anemia
Background
This case definition was developed by the Armed Forces Health Surveillance Center (AFHSC) for the purpose of epidemiological surveillance of iron deficiency anemia not related to pregnancy. Due to regular menstrual bleeding, iron deficiency anemia is a condition that primarily affects women although young men and women engaged in strenuous physical activity (e.g., during basic training or operational deployments) are also at risk.^1 Iron deficiency anemia causes fatigue and reduced physical work capacity. 2 As such, the condition may impact situations that require maximal performance such as on the field of combat. 3
Clinical Description
Iron deficiency anemia is a condition resulting from too little iron in the body which decreases the body’s ability to produce hemoglobin. Iron deficiency is the most common cause of anemia in the United States.^1 Iron deficiency anemia has many causes that fall into two main categories: increased iron needs (e.g., due to rapid growth, pregnancy, or blood loss); or decreased iron intake and absorption (e.g., due to lack of heme iron sources in the diet or excessive antacid use). A person with mild iron deficiency anemia may have no signs or symptoms of the condition; in more severe cases the individual may have one or more of the following common signs or symptoms (i.e., pale skin, fatigue, weakness, shortness of breath, headache, dizziness, cold hands and feet, irritability, glossitis and decreased work and school performance). Treatment is based on the underlying cause and often includes dietary changes and iron supplementation.^4
(^1) McClung, JP, Marchitelli, LJ, Friedl, KE and Young AJ. Prevalence of Iron Deficiency and Iron
Deficiency Anemia among Three Populations of Female Military Personnel in the US Army. J Am Coll Nutr. February 2006; Vol 25 (1), 64-69. (^2) Centers for Disease Control and Prevention. Iron deficiency – United States, 1999–2000. MMWR
2002; 51:897–899. (^3) Gardner G. Edgerton V, Senewiratne B. Barnard RJ. Ohira Y: Physical work capacity and metabolic
stress in subjects with iron-deficient anemia. Am J Clin Nutr 1977; 30: 910-7. (^4) Centers for Disease Control and Prevention. Recommendations to Prevent and Control Iron
Deficiency in the United States. MMWR 1998; 47 (No. RR-3) p. 5.
AFHSC Surveillance Case Definitions
Case Definition and Incidence Rules (continued)
Two outpatient medical encounters with any of the defining diagnoses of “unspecified anemia” (see ICD9 and ICD10 code lists below) in the first or second diagnostic position, followed by one outpatient medical encounter with any of the defining diagnoses of iron deficiency anemia (see ICD9 and ICD10 code lists below) in the first or second diagnostic position, and all occurring within a 365 - day period.
Incidence rules:
For individuals who meet the case definition:
The incidence date is considered the date of the first hospitalization or outpatient medical encounter that includes a diagnosis of iron deficiency anemia.
An individual can be considered an incident case once per lifetime.
If analysis requires recurrent case counts , an individual is considered a recurrent case if he or she has met the criteria for an incident case, and then has one hospitalization or outpatient medical encounter, 365 days or more after the incident date, with a defining diagnosis of iron deficiency anemia (see ICD9 and ICD10 code lists below) in the first or second diagnostic position.
Exclusions:
Individuals with possible pregnancy-related anemia within 2 years prior to a case defining encounter as suggested by:
- ICD9 codes 630-679 (complications of pregnancy childbirth, and the puerperium) and V22.x (normal pregnancy), V23.x (supervision of high-risk pregnancy), V24.x (postpartum care and examination), V27.x (outcome of delivery), V28.x (antenatal screening), V72.42 (pregnancy examination or test, positive result)
- ICD10 codes O00-O9A (pregnancy, childbirth and the puerperium) and Z33-Z (persons encountering health services in circumstances related to reproduction; does not include contraceptive management (Z30) or procreative management (Z31).
Codes
The following ICD9 and ICD10 codes are included in the case definition:
Condition ICD-10-CM Codes ICD-9-CM Codes
Iron deficiency anemia
D50 (iron deficiency anemia) 280 Iron deficiency anemias
- D50.0 (iron deficiency anemia secondary to blood loss; chronic)
280.0 (iron deficiency anemia secondary to blood loss; chronic)
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AFHSC Surveillance Case Definitions
cases; as such, the definition presented here was modified to exclude all pregnant women who had been pregnant within the 2 years prior to the case defining encounter.^6
The case finding criteria are limited to the first and second diagnostic position in an effort to capture cases of iron deficiency anemia that are the primary reason for an individual’s medical hospitalization or outpatient medical encounter. The criteria increase the sensitivity of the case definition but may underestimate the number of cases. Because iron deficiency anemia often occurs secondary to other medical conditions, expanding the case finding criteria to include the third and fourth diagnostic positions should be considered when planning special studies.
The specification that outpatient medical encounters must occur “within a 365- day period of each other” for case identification is used because individuals with iron deficiency anemia are typically treated for at least 6 months with iron supplementation. Six months of therapy is often required in a normal adult to rebuild the body’s iron stores.^9 In addition, patients not compliant with iron therapy secondary to the side effects of treatment may require treatment beyond six months to achieve adequate response. As such, 365 days was established to allow for the likelihood that “true” cases of iron deficiency anemia would be identified and treated within this timeframe.
The case definition includes criteria to capture cases of recurrent iron deficiency anemia. These cases are important because post treatment (i.e., when iron supplements are no longer consumed) iron deficiency anemia commonly returns.^10
Code Set Determination and Rationale
ICD9 codes 281.9 (unspecified deficiency anemia) and 285.9 (anemia, unspecified) are included in the code set because these codes are often used as first encounter criteria for case identification because the diagnosis of iron deficiency anemia often requires two or more medical encounters to determine the specific type of anemia. The first medical encounter for a patient with symptoms of anemia may be characterized and recorded as “other or unspecified anemia.”
Reports
None
Review
Jul 2015 Case definition reviewed and updated by the AFHSC Surveillance Methods and Standards (SMS) working group.
Jan 2013 Case definition reviewed and adopted by the AFHSC Surveillance Methods and Standards (SMS) working group.
Nov 2011 Case definition developed and reviewed by AFHSC staff.
Comments
None
(^9) Braunwald, E., Fauci, A., Longo, D. et al. 2008. Harrison’s Principles of Internal Medicine. 17th ed.
United States: McGraw-Hill Professional. (^10) Ross, EM : Evaluation and treatment of iron deficiency in adults. Nutr Clin Care 2002 ; 5 (5) : 220-4.
