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Background and objectivesThe incidence and risk of Mycobacterium tuberculosis in people with predialysis CKD has rarely been studied, although CKD prevalence is increasing in certain countries where Mycobacterium tuberculosis is endemic. We aimed to investigate the association between predialysis CKD and active Mycobacterium tuberculosis risks in a nation with moderate Mycobacterium tuberculosis risk.Design, setting, participants, & measurementsIn this nationwide retrospective cohort study, we reviewed the National Health Insurance Database of Korea, screening 17,020,339 people who received a national health screening two or more times from 2012 to 2016. Predialysis CKD was identified with consecutive laboratory results indicative of CKD (e.g., persistent eGFR <60 ml/min per 1.73 m2 or dipstick albuminuria). People with preexisting active Mycobacterium tuberculosis or kidney replacement therapy were excluded. A 1:1 matched control group without CKD was included with matching for age, sex, low-income status, and smoking history. The risk of incident active Mycobacterium tuberculosis, identified in the claims database, was assessed by the multivariable Cox regression model, which included both matched and unmatched variables (e.g., body mass index, diabetes, hypertension, places of residence, and other comorbidities).ResultsWe included 408,873 people with predialysis CKD and the same number of controls. We identified 1704 patients with active Mycobacterium tuberculosis (incidence rate =137.5/100,000 person-years) in the predialysis CKD group and 1518 patients with active Mycobacterium tuberculosis (incidence rate =121.9/100,000 person-years) in the matched controls. The active Mycobacterium tuberculosis risk was significantly higher in the predialysis CKD group (adjusted hazard ratio, 1.21; 95% confidence interval, 1.13 to 1.30). The risk factors for active Mycobacterium tuberculosis among the predialysis CKD group were old age, men, current smoking, low income, underlying diabetes, chronic obstructive pulmonary disease, and Kidney Disease Improving Global Outcomes CKD stage 1 (eGFR≥90 ml/min per 1.73 m2 with persistent albuminuria) or stage 4/5 without dialysis (eGFR<30 ml/min per 1.73 m2).ConclusionsIn the Korean population, the incidence of active Mycobacterium tuberculosis was higher in people with versus without predialysis CKD.

BackgroundAdditional study is warranted to investigate the causal effects between kidney function and obstructive lung disease.MethodsThis study was a bidirectional two-sample Mendelian randomisation (MR) analysis. The CKDGen genome-wide association study (GWAS) meta-analysis for estimated glomerular filtration rate (eGFR) including individuals of European ancestry (N=567 460) provided the genetic instrument for kidney function and outcome summary statistics. A GWAS for FEV1/FVC including individuals of European ancestry from the UK Biobank (N=321 047) provided the genetic instrument for FEV1/FVC and outcome data. A polygenic score (PGS) analysis was performed to test the causal estimates from kidney function to binary obstructive lung disease outcomes, including chronic obstructive pulmonary disease (COPD), asthma, and FEV1/FVC<70%, and to perform non-linear MR with individual-level UK Biobank data.ResultsThe causal estimates by summary-level MR indicated that genetically predicted increased kidney function was significantly associated with increased FEV1/FVC Z scores [10% increase in eGFR, beta 0.055 (0.024, 0.086)]. The PGS for increased eGFR showed a significant association with a reduced risk of FEV1/FVC<70% [OR 0.93 (0.87, 0.99)], COPD [OR 0.93 (0.87, 0.99)] and late-onset (≥50 years old) asthma [OR 0.93 (0.88, 0.99)]. The non-linear MR demonstrated that the causal effect from eGFR to FEV1/FVC was apparent in eGFR ranges lower than 60 mL/min/1.73 m2. On the other hand, genetically predicted FEV1/FVC showed nonsignificant causal estimates of eGFR change [beta 0.568% (−0.458, 1.605%)].ConclusionThis study supports kidney function impairment would be a causative factor for obstructive lung disease.

The association of lipid parameters with cardiovascular outcomes and the impact of kidney function on this association have not been thoroughly evaluated in chronic kidney disease (CKD) patients with diabetes. We reviewed the National Health Insurance Database of Korea, containing the data of 10,505,818 subjects who received routine checkups in 2009. We analyzed the association of lipid profile parameters with major adverse cardiovascular events (MACEs) risk and all-cause mortality in a nationally representative cohort of 51,757 lipid-lowering medication-naïve patients who had CKD and diabetes. Advanced CKD patients with eGFR <30 mL/min/1.73 m 2 (n = 10,775) had lower serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) but higher non-HDL-c levels and triglyceride (TG) to HDL-c ratios. There was a positive linear association between serum LDL-c and MACE risk in both early and advanced CKD patients (P <0.001 for trend), except for the category of LDL-c 30-49 mg/dL in extremely low LDL-c subgroup analyses. A U-shaped relationship was observed between serum LDL-c and all-cause mortality (the 4 th and 8 th octile groups; lowest hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.87-1.05 and highest HR 1.14, 95% CI 1.04-1.26, respectively). A similar pattern remained in both early and advanced CKD patients. The TG/ HDL-c ratio categories showed a positive linear association for MACE risk in early CKD (P <0.001 for trend), but this correlation disappeared in advanced CKD patients. There was no correlation between the serum TG/HDL-c ratio and all-cause mortality in the study patients. The LDL-c level predicted the risk for MACEs and all-cause mortality in both early and advanced CKD patients with diabetes, although the patterns of the association differed from each other. However, the TG/HDL-c ratio categories could not predict the risk for either