Prevalence of Anemia in Medical Practice: Community Versus Referral Patients

To compare the prevalence of anemia among community and referral patients. A Mayo Clinic laboratory database was searched for hemoglobin determinations between Jan. 1, 1985, and Dec. 31, 1989, in residents and nonresidents of Olmsted County, Minnesota, who were 20 years of age or older (a more restricted period within this interval was used for those 70 years of age or older). Using the World Health Organization criteria for anemia, we estimated the prevalence of anemia as of July 1, 1987, among Olmsted County residents 20 years of age or older (community patients) and compared this finding with the prevalence among non-Olmsted County patients of the same age registered at the Mayo Clinic during the same year (referral patients). The crude prevalence of anemia among Olmsted County men was less than that among male referral patients, but this difference was decreased by adjusting for the older mean age of referral patients (6.6% versus 7.0%; P = 0.01). Even after age-adjustment, the prevalence of anemia was greater among community women than among female referral patients (12.4% versus 8.2%; P<0.001). Before age 55 years, the prevalence of anemia was lower among men than among women, but after that age, anemia became more frequent in men, reaching a 44.4% prevalence among community men 85 years of age or older. The overall prevalence rate was sensitive to the criteria used to define a low hemoglobin level, however. Clinicians should be aware of the high prevalence of anemia, especially among elderly community patients. This precaution should help minimize the overlooked diagnosis of anemia and the failure to identify and treat its underlying cause.