Incidence of Anemia in Older People: An Epidemiologic Study in a Well Defined Population

Abstract

To assess the incidence and clinical spectrum of anemia among older people. Inception cohort assembled and followed by medical records linkage until death or last clinical contact through January 1994. Population-based study in Olmsted County, Minnesota. All 618 Olmsted County men and women aged 65 years or more with anemia by World Health Organization criteria that was first recognized in 1986. Age- and sex-adjusted incidence rates, corrected for prevalent anemia, and survival estimates using the Kaplan-Meier method, with calculation of standardized mortality ratios for specific causes of death. The corrected annual incidence of anemia rose with age, and rates were higher in men (90.3 per 1000; 95% CI, 79.2-101.4) than women (69.1 per 1000; 95% CI, 62.3-75.8). In 465 cases (75%), anemia was detected in conjunction with a hospitalization, but admission was due to anemia in only 57 instances. Half of the cases were caused by blood loss, two-thirds of these as a result of surgery. The cause of anemia was uncertain in 102 cases (16%). One-third of the patients were transfused with a median of 3 units each. Overall survival was worse than expected but was better among those with anemia caused by blood loss. Mortality attributable to malignancy, mental disorders, circulatory and respiratory diseases, ill-defined conditions, and injuries was significantly increased among these older patients with anemia. The incidence of anemia among older people is 4 to 6 times greater than that suspected clinically, rises with age, and is higher in men than in women. The apparent cause in half the cases is blood loss. Even mild anemia is associated with reduced survival, especially during the first year, but this could relate to underlying comorbid conditions.