Time in Target Range for Hemoglobin A1c and Systolic Blood Pressure: Association With Adverse Kidney Events.

RATIONALE &

OBJECTIVE

Time in target range (TTR) for systolic blood pressure (SBP) and hemoglobin A1c (HbA1c) integrates information about average and variability of levels over time. Their impact on kidney outcomes has not been fully evaluated. This study investigated the association of HbA1c-TTR and SBP-TTR, individually and jointly, with kidney outcomes among patients with type 2 diabetes and hypertension.

STUDY

DESIGN

Post hoc observational cohort analysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial data.

SETTINGS &

PARTICIPANTS

6,542 ACCORD participants with ≥ 3 HbA1c and SBP measurements during the first 12 months.

EXPOSURE: HbA1c-TTR and SBP-TTR during the first 12 months after randomization, each categorized separately as either 100% or in tertiles among the remaining study participants. In addition, 4 categories jointly assessing TTR for HbA1c and SBP were created: both HbA1c-TTR and SBP-TTR ≤ 80%, HbA1c-TTR ≤ 80% and SBP-TTR > 80%, HbA1c-TTR > 80% and SBP-TTR ≤ 80%, and both HbA1c-TTR and SBP-TTR > 80%.

OUTCOME: A composite kidney outcome, defined as incident albuminuria, estimated glomerular filtration rate decline ≥ 40% from baseline, or kidney failure.

ANALYTICAL APPROACH: Associations of HbA1c-TTR and SBP-TTR, individually and in combination with kidney outcomes, were analyzed using Cox proportional hazards models.

RESULTS

Compared with HbA1c-TTR of ≤ 49.6% (the lowest tertile), HbA1c-TTR of 100% was associated with a 20% lower risk of the composite kidney outcome (HR, 0.80 [95% CI, 0.68-0.94]). Compared with SBP-TTR of ≤50.7% (the lowest tertile), SBP-TTR of 100% was associated with a 32% lower risk of the composite kidney outcome (HR, 0.68 [95% CI, 0.58-0.80]). Participants with both HbA1c-TTR and SBP-TTR > 80% had a 29% (HR, 0.71 [95% CI, 0.61-0.83]) lower risk of the composite kidney outcome compared with participants with both HbA1c-TTR and SBP-TTR ≤ 80%.

LIMITATIONS: Limited duration of follow-up and low number of kidney failure events.

CONCLUSIONS

Longer time with HbA1c and SBP within target range was associated with a lower risk of adverse kidney events.

PLAIN-LANGUAGE SUMMARY: The concept of "time in target range" (TTR), defined as the proportion of time within a defined range, has been proposed in managing diabetes and hypertension. The combined effect of hemoglobin A1c (HbA1c)-TTR and systolic blood pressure (SBP)-TTR on adverse kidney events remains unknown. We evaluated the association of HbA1c-TTR and SBP-TTR, both individually and in combination, with incident kidney outcomes among patients who were enrolled in a clinical trial. We found that higher HbA1c-TTR and SBP-TTR were individually associated with a lower risk of adverse kidney events in patients with type 2 diabetes and hypertension. Having more time with both HbA1c and SBP within target range was also associated with a lower risk of adverse kidney outcomes compared with having either 1 individual parameter or neither individual parameter within target range.