Obstructive spirometry pattern and the risk of chronic kidney disease: analysis from the community-based prospective Ansan-Ansung cohort in Korea

Abstract

Objective: There have been limited studies on the relationship between obstructive spirometry pattern and the development of chronic kidney disease (CKD). We investigated the association between obstructive spirometry pattern and incident CKD development in a large-scale prospective cohort study.

Methods: We reviewed the data of 7960 non-CKD adults aged 40-69 years who participated in the Ansung-Ansan cohort, a prospective community-based cohort study. Prebronchodilation results for the ratio of forced expiratory volume per 1 s (FEV1) to forced vital capacity (FVC) were used as the primary exposure. The primary outcome was incident CKD, defined as the first event of an estimated glomerular filtration rate <60 mL/min/1.73 m². HRs and 95% CIs were calculated using multivariate Cox proportional hazard regression analysis.

Results: Over a mean follow-up period of 11.7 years, incident CKD developed in 511 subjects (6.4%). An increase of 0.1 in FEV1/FVC was associated with a decreased risk of incident CKD (HR 0.76, 95% CI 0.68 to 0.84, p<0.001). Compared with the fourth quartile, the HR (95 % CI) of the first quartile of FEV1/FVC ratio was 1.81 (1.39 to 2.36, p<0.001). In the restricted cubic spline curve, the renal hazard associated with a decreased FEV1/FVC ratio was evident at FEV1/FVC values <0.80, showing a U-shaped relationship. In subgroup analysis, the renal hazard associated with a decreased FEV1/FVC ratio was particularly evident in people without metabolic syndrome (p for interaction=0.018).

Conclusion: Decreased FEV1/FVC ratio was independently associated with an increased risk of incident CKD development, particularly in people without metabolic syndrome. Future studies need to be conducted to confirm these results.

Keywords: chronic airways disease; chronic renal failure; respiratory physiology.

Figure 1

Flow chart of the study subject selection. CKD, chronic kidney disease.

Figure 2

Kaplan-Meier CKD-free survival curves among four groups defined by the FEV1/FVC ratio. CKD, chronic kidney disease; FEV1, forced expiratory volume in 1 s; FVC, functional vital capacity.

Figure 3

Restricted cubic splines curve of Cox proportional hazards regression analysis according to the FEV1/FVC ratio. All covariates of model 2 shown in table 2 were used for adjustment. The solid line indicates the calculated line of association between the FEV1/FVC ratio and estimated HR. The shaded region represents the 95% CIs for value of HR according to the FEV1/FVC ratio. CKD, chronic kidney disease; FEV1, forced expiratory volume in 1 s; FVC, functional vital capacity.

Figure 4

Subgroup analysis for the relationship between the FEV1/FVC ratio and the risk of incident CKD. Adjusted beta and 95% CI were analysed using Cox proportional hazards regression analysis. All covariates of model two shown in table 2 were used to adjustment. BMI, body mass index; CKD, chronic kidney disease; CRP, C reactive protein; eGFR, estimated glomerular filtration rate; FEV1, forced expiratory volume in 1 s; FVC, functional vital capacity; MetS, metabolic syndrome; WCC, white cell count.