Association of lead and cadmium exposure with frailty in US older adults.

BACKGROUND

Environmental lead and cadmium exposure is associated with higher risk of several age-related chronic diseases, including cardiovascular disease, chronic kidney disease and osteoporosis. These diseases may lead to frailty, a geriatric syndrome characterized by diminished physiologic reserve in multiple systems with decreased ability to cope with acute stressors. However, no previous study has evaluated the association between lead or cadmium exposure and frailty.

METHODS

Cross-sectional study among individuals aged ≥ 60 years who participated in the third U.S. National Health and Nutrition Examination Survey and had either blood lead (N=5272) or urine cadmium (N=4887) determinations. Frailty was ascertained with a slight modification of the Fried criteria, so that individuals meeting ≥ 3 of 5 pre-defined criteria (exhaustion, low body weight, low physical activity, weakness and slow walking speed), were considered as frail. The association between lead and cadmium with frailty was evaluated using logistic regression with adjustment for relevant confounders.

RESULTS

Median (intertertile range) concentrations of blood lead and urine cadmium were 3.9 µg/dl (2.9-4.9) and 0.62 µg/l (0.41-0.91), respectively. The prevalence of frailty was 7.1%. The adjusted odds ratios (95% confidence interval) of frailty comparing the second and third to the lowest tertile of blood lead were, respectively, 1.40 (0.96-2.04) and 1.75 (1.33-2.31). Lead concentrations were also associated with the frequency of exhaustion, weakness and slowness. The corresponding odds ratios (95% confidence interval) for cadmium were, respectively, 0.97 (0.68-1.39) and 1.55 (1.03-2.32), but this association did not hold after excluding participants with reduced glomerular filtration rate: 0.70 (0.43-1.14) and 1.09 (0.56-2.11), respectively.

CONCLUSIONS

In the US older adult population, blood lead but not urine cadmium concentrations showed a direct dose-response relationship with frailty. These findings support that lead exposure increases frailty in older adults.