Introduction:
Since dialysis adversely affects the quality of life and is related to
high rates of cardiovascular events and mortality, avoiding the need for
dialysis is clinically relevant. Although both hyperglycemia and
hypertension are highly predictive of kidney disease [1], only a few
studies have investigated the associations between the severity of
hypertension and risk of end-stage renal disease (ESRD) especially the
initiation of renal replacement therapy in the presence or absence of
diabetes mellitus (DM) in the same cohort at the same time and under the
same conditions.
More strict blood pressure targets were recently recommended in the
guidelines for hypertension by the American College of Cardiology (ACC)
and the American Heart Association (AHA) [2]. In these guidelines,
the definition of adult hypertension was reduced from the long-standing
threshold of 140/90 mm Hg to 130/80 mm Hg. Although DM and hypertension
defined as SBP ≥140 mmHg, DBP ≥90 mmHg or the use of antihypertensive
treatment are well-known risk factors for ESRD defined according to the
initiation of renal replacement therapy [3], various SBP levels have
not been investigated with regard to the prevention of dialysis
according to DM status. Such an investigation would have clinical
relevance. The risk of chronic kidney disease (CKD) defined as the
requirement for dialysis, transplantation or by the notation of kidney
disease on the death certificate and confirmed by medical record review
significantly increased from SBP ≥160 mmHg compared to SBP <120 mmHg
with adjustment for DM [4]. Also, the risk of ESRD defined as
receipt of renal transplant or maintenance dialysis increased in
accordance with increases in SBP with adjustment for DM [5].
Although Hsu et al. [5] investigated the impacts of the presence of
DM and stratified SBP on ESRD defined as described above, HbA1c was not
used in defining DM. Moreover, only age was adjusted for as a covariate.
Tozawa et al. [6] showed that elevated SBP was a risk factor for the
development of ESRD among Japanese with and without DM. Also, Iseki et
al. [7] showed that hyperglycemia defined as fasting blood glucose
≥126 mmHg was a significant risk factor for the development of ESRD in a
Japanese general population. However, these studies [6.7] did not
use HbA1c to define DM and also did not evaluate the impact of
combinations of various SBP cut-offs among people with and without DM on
starting dialysis. Thus, the impacts of blood pressure control and
cut-off values on renal replacement therapy among people with and
without DM are still unknown.
Moreover, although patients with renal disease or on dialysis tend to be
prescribed hypertensive medication more often than those without renal
disease or on dialysis [1.4.8], these studies [4.5] did not
adjust for antihypertensive agents as a covariate. Thus, the effects of
antihypertensive medication must be considered in evaluating the impact
of various SBP levels on the initiation of dialysis.
Therefore, we investigated the risk of various SBP values for the
initiation of dialysis in the presence or absence of DM in addition to
considering the risk of various levels of SBP with adjustments for the
use of antihypertensive medications.