Introduction: Anemia among the elderly population is often under-diagnosed or goes undetected. The incidence of anemia among this population is believed to be 4–6 times greater than reported, with an underlying condition found in over half of anemics, especially men and older individuals (

J Am Geriatr Soc
). Given the number of comorbidities in elderly patients a better understanding of the relationship between these underlying conditions and anemia is warranted.

Methods: A retrospective analysis of a large health claims database (1997–2002) examined the prevalence of anemia and associated comorbidities in patients >/=65 years with >/=3 years of follow-up. Chronic anemia was defined using the WHO criteria (hemoglobin [Hb] </= 12 for women; </= 13 for men) among patients with >/=2 Hb measurements >30 days and </= 1 year apart; patients with nutrient deficiencies, chemotherapy, HIV, HCV, and hematological diseases were excluded. Comorbidities were defined by the presence of >/=2 ICD-9 diagnosis codes or >/=1 CPT code for each condition, and categorized a priori as ‘linked’ [potential association with anemia (rheumatoid arthritis and/or lupus, CKD, CHF, untreated cancer and TB)] or ‘non-linked’ [not associated with anemia (diabetes, asthma and/or COPD, osteoarthritis, osteoporosis, hypertension and CVD]. Patients were categorized by number of comorbidities (0–1, 2–3, 4–5, >5) and age (65–74, 75–84, >/= 85).

Results: The mean age among the study sample (chronic anemics: n=2729; non-anemics: n=7648) was 72.9 years (SD=5.9); 56.8% were women and 31.2% were African American. Mean Hb was similar for all groups (65–74 [n=1446]: 11.7±0.89; 75–84 [1080]: 11.7±0.94; >/=85[203]: 11.6±0.96, and >/=65[2729]: 11.7±0.91). Only 19.6% of anemics had an anemia diagnosis code. Patients with chronic anemia had significantly more comorbid conditions than those without anemia (p<.0001) (chronic anemics: 9.6%, 43.9%, 35.8% and 10.7%; non-anemics: 20.1%, 54.3%, 22.9% and 2.8% with 0–1, 2–3, 4–5 and >5 comorbidities, respectively). The same trend was observed across all age groups. Regardless of anemia status, the number of comorbid conditions increased with age among patients with and without anemia, however, patients with anemia were 2.5 times as likely to have >3 comorbidities compared to patients without anemia across all ages (OR=2.51, 95%CI=2.30–2.75). The number of linked comorbidities was observed to increase with age. Approximately 7% of non-anemic patients had >/=2 linked diseases, while almost 23% of chronic anemics had >/=2 linked comorbidities (p<.0001). Non-linked conditions were twice as common among anemics than non-anemics (>3 conditions: 19.5% vs. 11.0%, p<.0001).

Conclusions: Comorbid disease is common among older adults and is frequently unrecognized. Elderly patients with chronic anemia are more likely to have comorbid disease than non-anemic patients, including conditions not considered to be associated with anemia. These data identify a potential relationship between anemia and comorbid conditions in the elderly.

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