Objective: To compare the prevalence of anemia among community and ref
erral patients. Design: 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 interv
al was used for those 70 years of age or older).Material and Methods:
Using the World Health Organization criteria for anemia, we estimated
the prevalence of anemia as of July 1, 1987, among Olmsted County resi
dents 20 years of age or older (community patients) and compared this
finding with the prevalence among non-Olmsted County patients of the s
ame age registered at the Mayo Clinic during the same year (referral p
atients). Results: The crude prevalence of anemia among Olmsted County
men was less than that among male referral patients, but this differe
nce was decreased by adjusting for the older mean age of referral pati
ents (6.6% versus 7.0%; P = 0.01). Even after age-adjustment, the prev
alence of anemia was greater among community women than among female r
eferral patients (12.4% versus 8.2%; P<0.001). Before age 55 years, th
e prevalence of anemia was lower among men than among women, but after
that age, anemia became more frequent in men, reaching a 44.4% preval
ence among community men 85 years of age or older. The overall prevale
nce rate was sensitive to the criteria used to define a low hemoglobin
level, however. Conclusion: Clinicians should be aware of the high pr
evalence 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.