Particulate Air Pollution and Post-Discharge Recovery Among Older Adults Hospitalized for Heart Failure in the United States.

BACKGROUND The impact of exposure to fine particulate matter (PM2.5) on post-discharge recovery in older adults already hospitalized for heart failure remains unclear. We evaluated associations between exposure to PM2.5 and days spent at home (DAH) as well as mortality in a nationwide representative sample of U.S. adults aged 65 years and older.

METHODS Data from 66 854 Medicare Fee-for-service beneficiaries with heart failure hospitalization (2017-2019) were linked with validated, model-derived mean PM2.5 concentrations at Zip Code Tabulation Areas level during the month of hospital admission. Post-discharge 180-day DAH was defined as days alive minus days spent in inpatient hospitals, hospital observation units, nursing facilities, or emergency departments. All-cause mortality was assessed as time from hospital discharge to death within 180 days. Quantile regression and Cox proportional regression models, adjusted for covariates, were used to quantify associations.

RESULTS Exposure to the highest quartile PM2.5 level (>8.61 µg/m3) was associated with 5.05 fewer DAH (95% CI: -8.61, -1.48; P = 0.006) after discharge at the 20th percentile of DAH, compared with those exposed to the lowest PM2.5 quartile ( < =5.90 µg/m3). Exposure to the highest quartile PM2.5 levels was also associated with higher risk of all-cause mortality within 180 days after hospitalization as compared to the lowest PM2.5 quartile (hazard ratio = 1.05 (95%CI: 1.004-1.10, P = 0.033).

CONCLUSIONS Particulate air pollution may negatively impact recovery more strongly at the lower tail of recovery than at the median or higher tail, highlighting the need for targeted intervention strategies to protect the most vulnerable patients.