Blood Pressure, Kidney Function, and Kidney Mortality Among Mexican Adults.
RATIONALE & OBJECTIVE Chronic kidney disease (CKD) is a major cause of death in Mexico and blood pressure (BP) may be an important contributor. This study investigated the associations of BP with CKD, albuminuria, and death from kidney failure. STUDY DESIGN Prospective cohort study. SETTING & PARTICIPANTS 133,470 adults aged ≥35 to <85 years without CKD or other chronic disease (except diabetes), recruited from two districts of Mexico City between 1998 and 2004, and who survived ≥5 years after recruitment. A random subset of 9198 underwent additional evaluation 2015-2019. EXPOSURES Systolic BP (SBP), diastolic BP (DBP) and hypertension (participant report of taking blood pressure lowering medication or BP ≥140/90 mm Hg). OUTCOMES Kidney failure mortality during follow-up, and CKD (self-report and/or eGFR <60 mL/min/1.73m2) and albuminuria at the time of repeat clinical evaluation. ANALYTICAL APPROACH Multivariable Cox regression for the association of BP with kidney failure mortality and multivariable logistic regression for the association of baseline BP with CKD and albuminuria at the time of re-evaluation. RESULTS Among all participants, SBP showed a continuous "log-linear" association with kidney failure mortality; each 20 mm Hg lower SBP being associated with 24% lower risk at ages 40-84 years (kidney failure death hazard ratio [HR] 0.76, 95% confidence interval 0.69-0.84). The association was stronger among those without diabetes (HR 0.54, 0.45-0.69) than with diabetes (HR 0.90, 0.80-1.01) but the absolute excess risk associated with higher BP was similar in these subgroups. Hypertension accounted for 9% of kidney failure deaths. Among those re-evaluated, 6% had developed CKD and 25% had albuminuria. 20 mm Hg lower baseline SBP was associated with 24% lower odds of both CKD (odds ratio [OR] 0.76, 0.68-0.85) and albuminuria (OR 0.76, 0.68-0.84) at the time of re-evaluation. Results were similar for DBP. LIMITATIONS Baseline urine samples were unavailable and kidney function trends over time could not be assessed. CONCLUSIONS This large prospective study in Mexican adults highlights elevated BP as a major modifiable risk factor for kidney failure mortality, CKD, and albuminuria.