. 2019 Feb 1;199(3):321–332. doi: 10.1164/rccm.201803-0402OC

Table 2.

Associations between Albuminuria, Initial Lung Function, and Absolute and Relative Rates of Change in Lung Function in Adults without Prevalent Chronic Lower Respiratory Diseases

	Albuminuria Categories						ln Albuminuria
	<2 mg/dl (n = 891)	2–3 mg/dl (n = 1,226)	3–6 mg/dl (n = 3,648)	6–12 mg/dl (n = 2,497)	12–30 mg/dl (n = 1,644)	≥30 mg/dl (n = 1,055)	Per SD (95% CI) (n = 10,961)	P Value
Initial
FEV₁, ml	Ref.	0.65	−1.39	−16.80	−25.15	−63.47^*	−22.64 (−29.86 to −15.42)	<0.0001
FEV₁/FVC, %	Ref.	0.47^*	0.12	0.41^*	0.48^*	0.16	0.06 (−0.04 to 0.15)	0.27
Absolute rate of change
FEV₁, ml/yr	Ref.	−0.24	−1.61	−1.92	−2.51^*	−2.98^*	−0.89 (−1.50 to −0.27)	0.0047
FEV₁/FVC, % yr	Ref.	0.01	−0.02	−0.04^*	−0.06^*	−0.03	−0.02 (−0.3 to −0.01)	0.0011
Relative rate of change^†
FEV₁, % average rate (−31.5 ml/yr)	Ref.	−0.77	−5.12	−6.10	−7.94^*	−9.43^*	−2.81 (−4.76 to −0.86)	0.0047
FEV₁/FVC, % average rate (−0.2%/yr)	Ref.	5.59	−10.57	−22.09^*	−38.42^*	−21.21	−11.02 (−17.62 to −4.43)	0.0011

Definition of abbreviations: CI = confidence interval; Ref. = reference.

Results exclude participants with prevalent clinical chronic lower respiratory disease, airflow limitation (FEV₁/FVC < lower limit of normal [LLN]), or restriction on spirometry (FEV₁/FVC > LLN, FVC < LLN) at time of albuminuria measurement. Linear mixed models predicted lung function from baseline albuminuria, time since albuminuria assessment (years), and their multiplicative interaction term, with cohort-specific unstructured covariance matrix, adjusted for time-varying height, weight, and smoking status; time-invariant age (centered), birth-year (centered), study, sex, race/ethnicity, educational attainment, pack-years of smoking, hypertension status, hypertension medications, systolic blood pressure, diastolic blood pressure, total cholesterol, angiotensin-converting enzyme inhibitor/angiotensin-II receptor blocker medication, diabetes status, diabetes medication, and estimated glomerular filtration rate. All time-invariant factors were modeled for both cross-sectional associations and longitudinal associations via inclusion of the covariate as well as its interaction with time since albuminuria assessment. Separate models were run using categorical (grouped quantile) and continuous (natural log–transformed albuminuria) predictors, and effect estimates were reported per category or per SD, respectively. Model fit was compared by the Akaike information criterion (AIC). For FEV₁, the AIC for the categorical analysis was lower (better) than for the continuous term (295,296.8 vs. 295,509.5). For the FEV₁/FVC, the AIC for the categorical analysis was higher (worse) than for the continuous term (121,725.5 vs. 121,715.7).

Statistically significant at P < 0.05.

^{^†}

Estimates for absolute and relative rates of change in lung function are derived from the same model. The estimates for the latter reflect the estimates for the former divided by the model-based average rate of decline in the total sample; negative values indicate greater loss of lung function.