Low-income older adults who live in more affluent areas are healthier than those living in less affluent areas, according to a study published in Annals of Internal Medicine. Researchers found that the prevalence of chronic conditions among low-income older adults is highly spatially correlated.

The researchers conducted a cross-section association analysis using 100% of Medicare administrative records for 2015 to analyze the relationship between the prevalence of chronic conditions in low-income older adults (N=6,363,097) and the affluence of their area of residence. Local areas were defined as a commuting zone because this geographic aggregation reflects ties to local economic and social activity. Investigators computed the adjusted prevalence for 48 chronic health conditions in 736 commuting zones. Spatial covariation of prevalence was assessed and a per-commuting zone composite condition prevalence index (local area chronic condition index [LACCI]) was constructed using factor analysis. Associations between morbidity and local affluence were measured by comparing house value deciles across median commuting zones.

Of the 6,363,097 study participants, 61% were white and 67% were women. The mean age of participants was 77.7 years (SD, 8.2) and mean duration of receiving low-income Part D Medicare subsidies was 68.1 months (SD, 41.3). The crude prevalence of the 48 conditions researchers assessed ranged from 0.6 per 100 for posttraumatic stress disorder to 72.5 per 100 for hypertension, with the 5 most prevalent conditions being hypertension, anemia, hyperlipidemia, osteoarthritis and rheumatoid arthritis, and ischemic heart disease.

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Adjusted prevalence varied substantially by commuting zone. For example, while the average prevalence of hypertension was 75.0/100 in an average commuting zone, the prevalence varied from 34.8/100 around Bethel, Alaska, to 91.9/100 around Lake Providence, Louisiana (SD, 10.0; interquartile range [IQR], 70.1-83.6). The average prevalence of diabetes was 38.8/100 in the average commuting zone, but varied from less than 12/100 in Alaska to 63.0/100 near Frederick, Oklahoma (SD, 7.6; IQR, 35.2-43.6). The average prevalence of Alzheimer’s disease and related dementia was 22.4/100 in the average commuting zone, but varied from 4.8/100 in the Bethel, Alaska, area to 36.3/100 around the Madison, Indiana, area (SD, 4.5; IQR, 19.6-24.4).

In urban commuting zones, LACCIs in the second decile were 14.5 points higher than in the top decile (SD difference, 1.6; 95% CI, 5.5-23.6; P =.002 vs LACCI, 95.5), and while LACCI varied by decile in a similar fashion in rural areas, the average LACCI in rural commuting zones was substantially lower, with a difference of 8.2 points (P =.25) in the first-lowest decile and 8.5 points (P =.048) in the second-lowest decile.

Overall, researchers found that the health of low-income older Americans varies substantially by geographic region in a way that cannot be attributed to a narrow set of conditions or to one specific disease. Populations of study participants tended to be systematically unhealthy or systematically healthy based on area affluence, with chronic condition prevalence being high in unhealthy areas. The study investigators concluded, “These results suggest the likely importance of local location-based public health efforts that target the general health of the population rather than any specific conditions.”

Reference

Polyakova M, Hua LM. Local area variation in morbidity among low-income, older adults in the United States: a cross-sectional study [published online September 10, 2019]. Ann Intern Med. doi:10.7326/M18-2800