Observational Modeling of Strict vs Conventional Blood Pressure Control in Patients With Chronic Kidney Disease

IMPORTANCE: The effect of strict blood pressure control on clinical outcomes in patients with chronic kidney disease (CKD) is unclear. OBJECTIVE: To examine the association of a treated systolic blood pressure (SBP) of <120 mmHg with the currently recommended SBP of <140 mmHg in a national CKD database of United States veterans. DESIGN: Historical cohort. SETTING: All US Department of Veterans Affairs healthcare facilities. PARTICIPANTS: Using a database of 651,749 CKD patients, we identified 77,765 individuals with estimated GFR<60 ml/min/1.73m(2) and uncontrolled hypertension, who then had administration of one or more additional blood pressure medications with evidence of a decrease in systolic blood pressure. 5,760 patients experienced follow-up treated blood pressure of <120 mmHg and 72,005 patients had SBP 120–139 mmHg. Propensity scores were calculated to reflect each individual’s probability for future SBP<120 vs. 120–139 mmHg. MAIN OUTCOME MEASURES: The effect of SBP on all-cause mortality was evaluated by the log-rank test, and in Cox models adjusted for propensity scores. RESULTS: A total of 19,517 patients died during a median follow-up of 6.0 years, with 2,380 deaths in the SBP <120 mmHg group (death rate, 95%CI: 80.9/1000 patient-years, 77.7–84.2) and 17,137 deaths in the SBP 120–<140 mmHg group (41.8/1000 patient-years, 41.2–42.4), p< 0.001. The mortality hazard ratio (95%CI) associated with follow-up SBP<120 vs. 120–139 mmHg was 1.70 (95%CI: 1.63–1.78) after adjustment for propensity scores. CONCLUSION AND RELEVANCE: Our results suggest that stricter SBP control is associated with higher all-cause mortality in CKD patients. Confirmation of these findings by ongoing clinical trials would suggest that modeling of therapeutic interventions in observational cohorts may offer useful guidance for the treatment of conditions which lack clinical trial data