Prevalence of Neutropenia in the U.S. Population: Age, Sex, Smoking Status, and Ethnic Differences

3 April 2007 | Volume 146 Issue 7 | Pages 486-492

Background: Benign reductions in neutrophil counts may be more common at certain ages and in certain ethnic groups and may be affected by sex and smoking status.

Objective: To determine differences in neutrophil counts in the U.S. population according to ethnicity, age, sex, and smoking status.

Design: Population-based, cross-sectional study.

Setting: Various locations in the United States.

Participants: 25 222 participants in the 1999 to 2004 National Health and Nutrition Examination Survey who were 1 year of age or older.

Measurements: Complete blood counts and comparison of means and the proportion of participants with neutropenia.

Results: Relative to white participants, black participants had lower leukocyte counts (mean difference, 0.89 x 10⁹ cells/L; P < 0.001), lower neutrophil counts (0.83 x 10⁹ cells/L; P < 0.001), and similar lymphocyte counts (0.022 x 10⁹ cells/L; P = 0.36), whereas Mexican-American participants had slightly higher mean leukocyte counts (0.16 x 10⁹ cells/L; P = 0.014), higher neutrophil counts (0.11 x 10⁹ cells/L; P = 0.026), and higher lymphocyte counts (0.095 x 10⁹ cells/L; P < 0.001). The prevalence of neutropenia (neutrophil count <1.5 x 10⁹ cells/L) was 4.5% among black participants, 0.79% among white participants, and 0.38% among Mexican-American participants. The prevalence of neutropenia was higher among males and children younger than 5 years of age. Neutrophil counts less than 1.0 x 10⁹ cells/L were observed in fewer than 1% of the overall sample (0.57% in black participants, 0.11% in white participants, and 0.08% in Mexican-American participants). Smoking was associated with higher leukocyte and neutrophil counts but had a smaller effect among black and Mexican-American participants than among white participants.

Limitation: Because estimates are based on single measures, fluctuations over time could not be determined.

Conclusions: In the United States, neutrophil counts are lower in black persons than in white persons and neutropenia is more prevalent in black persons. Neutrophil counts are slightly higher in Mexican-American persons than in white persons, and neutropenia is uncommon in both groups. The clinical implications of these findings are unclear, but they suggest that when determining the need for a diagnostic evaluation for neutropenia, clinicians should consider the patient's age, sex, ethnicity, and smoking status.

Editors' Notes Context Low neutrophil counts may be more common in certain ethnic groups and ages. Contribution When blood count data were analyzed from a national sample of presumably healthy persons, the authors found that neutrophil counts were lower and neutropenia was more prevalent in U.S. black persons compared with white persons. Smoking was associated with increased neutrophil counts, especially in white persons. Cautions Blood counts were measured only once and could have differed in a second measurement or changed over time. Implications Race and smoking status influence the number of blood neutrophils and should be taken into account when considering the need to evaluate abnormal counts. —The Editors

 

Author and Article Information

From National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, and Social & Scientific Systems, Inc., Silver Spring, Maryland.

Acknowledgments: The authors thank Drs. Geraldine Schechter and Daniel Wright for their helpful comments and Keith Rust for statistical analyses.

Potential Financial Conflicts of Interest: None disclosed.

Grant Support: By the intramural research program of the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health.

Requests for Single Reprints: Griffin P. Rodgers, MD, Molecular and Clinical Hematology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, Building 10, 9N 119, Bethesda, MD 20892; e-mail, gr5n{at}nih.gov.

Current Author Addresses: Drs. Hsieh, Tisdale, and Rodgers: Molecular and Clinical Hematology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, Building 10, 9N 119, Bethesda, MD 20892.

Dr. Everhart: Epidemiology and Clinical Trials Branch, Division of Digestive Diseases and Nutrition, National Institute of Diabetes and Digestive and Kidney Diseases, 2 Democracy Plaza, Room 655, 6707 Democracy Boulevard, MSC 5450, Bethesda, MD 20892-5450.

Ms. Byrd-Holt: Computer Systems Data Analysis Division, Social & Scientific Systems, Inc., 8757 Georgia Avenue, 12th Floor, Silver Spring, MD 20910.

Author Contributions: Conception and design: M.M. Hsieh, J.E. Everhart, J.F. Tisdale, G.P. Rodgers.

Analysis and interpretation of the data: M.M. Hsieh, J.E. Everhart, D.D. Byrd-Holt, J.F. Tisdale.

Drafting of the article: M.M. Hsieh, J.E. Everhart, D.D. Byrd-Holt, J.F. Tisdale, G.P. Rodgers.

Critical revision of the article for important intellectual content: M.M. Hsieh, J.E. Everhart, J.F. Tisdale, G.P. Rodgers.

Final approval of the article: M.M. Hsieh, J.E. Everhart, D.D. Byrd-Holt, J.F. Tisdale, G.P. Rodgers.

Statistical expertise: J.E. Everhart, D.D. Byrd-Holt.

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