Demographic and Health Surveys Methodology - Measure DHS

Handling of Missing ValuesChildren who were not tested and those children whose values were not recorded are excluded from boththe denominator and the numerators.Notes and ConsiderationsChildren less than six months of age are not included because they have higher levels of hemoglobin atbirth and just after birth and thus may distort the indication of prevalence of anemia.People residing at higher altitudes (greater than 1,000 meters (3,300 feet)) have higher Hb and Hct levelsthan those residing at sea level. This variation is due to the lower oxygen partial pressure at higheraltitudes, a reduction in oxygen saturation of blood, and a compensatory increase in red cell production toensure adequate oxygen supply to the tissues. Thus, higher altitude causes a generalized upward shift ofthe Hb distributions. This shift may be associated with the underdiagnosis of anemia for residents ofhigher altitudes when sea-level cutoffs are applied (CDC, unpublished data). Therefore, the properdiagnosis of anemia for those residing at higher altitudes requires an upward adjustment of Hb cutoffs.The values for altitude-specific adjustment of Hb are derived from data collected by the CDC PediatricNutrition Surveillance System on children residing at various altitudes in the mountain states. Altitudeaffects Hb levels throughout pregnancy in a similar way (J.N. Chatfield, unpublished data). Altitude datashould always be obtained to adjust where the altitude of the dwelling is more than 1,000 meters.Substitution of cluster altitude is usually accepted instead of altitude for each dwelling in the cluster.ReferencesCenters for Disease Control and Prevention. 1998. Recommendations to prevent and control irondeficiency in the United States. Morbidity and Mortality Weekly Report 47 (RR-3): 1–29.Centers for Disease Control and Prevention. 1989. Current trends CDC criteria for anemia in children andchildbearing-aged women. Morbidity and Mortality Weekly Report 38, (22): 400–404.Guide to DHS Statistics 139 Updated October 2012