Associations of albuminuria with interstitial lung abnormalities in older community-dwelling adults confounded by age.

BACKGROUND

Pulmonary microvascular dysfunction has been suggested to be an early feature of interstitial lung changes, which may precede interstitial lung disease. The prospective association of albuminuria, a marker of endothelial dysfunction, with interstitial lung abnormalities (ILA) and high-attenuation areas (HAA) remains unexplored.

METHODS

The study included participants with available spot urinary albumin-creatinine ratio (UACR) and computed tomography data for ILA and HAA enrolled in two independent cohorts, Multi-Ethnic Study of Atherosclerosis (MESA; n=2248) and Age Gene/Environment Susceptibility (AGES)-Reykjavik (n=3509). HAA were defined as the percentage of imaged lungs with attenuation between -600 and -250 HU (MESA only). Regression modelling was performed to assess the associations of UACR with ILA and HAA, adjusted for anthropometric and demographic variables and kidney function. Cox proportional-hazard models were used to examine whether ILA modified the association between albuminuria and all-cause mortality.

RESULTS

Log-transformed UACR was significantly associated with ILA, with an OR 1.21 (95% CI 1.12-1.30) in MESA and OR 1.13 (95% CI 1.06-1.21) in AGES-Reykjavik. In multivariable-adjusted models incorporating age, albuminuria was no longer associated with ILA, nor with ILA progression in AGES-Reykjavik. In MESA, higher levels of albuminuria were associated with greater HAA (mean increase of 1.01% per 1-unit increment in log-transformed UACR, 95% CI 1.01-1.02%), even after adjusting for covariates including age. Albuminuria was more strongly associated with death among those with ILA in MESA, but not in AGES-Reykjavik.

CONCLUSIONS

Albuminuria was not associated with ILA after accounting for chronological age. Our findings suggest that there may be a common systemic pathology of ageing that underlies albuminuria and interstitial lung changes.