Blood pressure modifies outcomes in patients with stage 3 to 5 chronic kidney disease

Observational studies have demonstrated that low blood pressure is related to poor clinical outcomes in patients with chronic kidney disease (CKD). Subgroup analyses from the SPRINT trial showed that targeting systolic blood pressure under 120 mmHg is less beneficial for patients with CKD. Although malnutrition and inflammation are common in patients with advanced CKD, such patients are usually excluded from clinical trials. Therefore, we hypothesized that malnutrition-inflammation-cachexia syndrome could explain this J-shaped relationship. To test this, we studied 2441 patients with CKD stages 3-5 who received anti-hypertensive treatment for at least one year. Averaged blood pressures of the first year were used in the analyses. Fine-Gray competing risks regression showed a J-shaped relationship between continuous systolic blood pressure and end-stage kidney disease (ESKD) with a nadir risk at a systolic blood pressure of 120 mmHg. Adjusted sub-distribution hazard ratios of categorical systolic blood pressure 100-109 and 110-119 mmHg were 2.17 (95% confidence interval: 1.21-3.89) and 1.37 (0.94-1.99) for ESKD, respectively, compared with systolic blood pressures of 120-129 mmHg. Cox regression also showed J-shaped relationships between continuous systolic or diastolic blood pressures, and the composite outcomes of cardiovascular events and all-cause mortality. Logistic regression demonstrated the odds ratios of blood pressure components for Malnutrition-Inflammation Scores over 4 were J-shaped. Sub-distribution hazard ratios of systolic blood pressure 100-119 mmHg for ESKD was higher in those with a Malnutrition-Inflammation Score over 4, compared to 0.93 (0.53-1.63) in those with a score of 4 or under with significant interaction. Thus, malnutrition-inflammation-cachexia syndrome is associated with low blood pressure and modifies the J-shaped relationship in patients with advanced CKD.