Association of systolic blood pressure with incident chronic kidney disease estimated by marginal structural model: a nationwide population-based study

Background: We aimed to investigate the association between systolic blood pressure (SBP) and risk of incident chronic kidney disease (CKD) using marginal structural model (MSM) to reflect mutual effects of exposure and confounders on the outcome. Methods: A total of 195,970 adults with an estimated glomerular filtration rate (eGFR) of >60 mL/min/1.73 m2 and no proteinuria were included from a nationally representative sample cohort of Korean population. SBPs were measured through national health examinations. Primary outcome was incident CKD, defined as a composite of events of a decrease in eGFR to <60 mL/min/1.73 m2 or a newly developed proteinuria for at least two consecutive measurements. The association between SBP and risk of CKD was examined using Cox model, time-dependent Cox model, and MSM. Results: During a follow-up of 5 years, CKD occurred in 3,355 participants (1.7%). With SBP treated as a continuous variable, each 10-mmHg increment was associated with higher risk for incident CKD, regardless of analytical models used. Compared to SBP group of 120-129 mmHg, hazard ratios (95% confidence intervals) for incident CKD for SBP groups of <110, 110-119, 130-139, and >= 140 mmHg in MSM were 0.70 (0.62-0.80), 0.85 (0.77-0.95), 1.16 (1.05-1.27), and 1.63 (1.47-1.80), respectively. Conclusion: In this nationwide study, we found a significant relationship between higher SBP and higher risk of incident CKD. Further studies are warranted to verify the potential significance of high SBP as a preventable risk factor for the development of CKD in those with preserved renal function.