medwireNews: Resistant hypertension is linked to an increased risk for cardiovascular outcomes in type 1 diabetes, with renal damage accounting for a large part of the association, say researchers.
Per-Henrik Groop (University of Helsinki, Finland) and team defined resistant hypertension as having blood pressure (BP) of 130/85 mmHg or higher despite use of at least three antihypertensive classes, including a diuretic, or requiring at least four antihypertensive drugs to achieve BP target.
This applied to 18.7% of 1103 participants of the Finnish Diabetic Nephropathy Study who were taking antihypertensive treatment. The study participants overall were aged an average of 43.7 years, 56% were men, and their average type 1 diabetes duration was 26.3 years.
Individuals with resistant hypertension had a significantly higher 15-year cumulative risk for coronary heart disease (CHD) than other study participants, at 35.1% compared with 24.8% in people with BP that was uncontrolled but not treatment resistant (57.9% of the cohort), and just 12.8% in those with controlled BP (23.4% of the cohort).
This equated to nearly a threefold increased risk for CHD for people with resistant hypertension versus those with controlled BP, and the association remained significant albeit somewhat reduced after accounting for factors such as age, sex, waist-to-hip ratio, and previous CHD.
However, people with resistant hypertension had a markedly reduced average estimated glomerular filtration rate (eGFR), at 43.3 mL/min per 1.73 m2 compared with 80.5–82.6 mL/min per 1.73 m2 in the other two groups. Likewise, the prevalence of macroalbuminuria was 74.3% versus 34.5–36.1%.
After accounting for albuminuria status, the association between resistant hypertension and CHD lost statistical significance.
“This is in line with clinical findings showing a strong association between [resistant hypertension] and [diabetic nephropathy] that, in turn, is known to be a dominant contributor to excess cardiovascular mortality,” write the researchers in Diabetes Care.
Furthermore, resistant hypertension was significantly associated with the risk for stroke; this retained statistical significance after accounting for albuminuria status, but not after further adjustment for eGFR.
People with resistant hypertension also had an increased risk for progression of diabetic nephropathy, with this occurring in 56.6%, compared with around 25% of the other groups. The increased risk remained after accounting for potential confounders, and the risk was particularly marked in those with macroalbuminuria at baseline.
The researchers note that BP control is particularly difficult in patients with late-stage kidney disease, with or without type 1 diabetes.
“Because [resistant hypertension] and advanced kidney disease is a challenging combination, robust evidence on their close relationship in various clinical conditions, such as in type 1 diabetes, is urgently needed to be able to identify the high-risk individuals who should be provided optimal clinical care and counseling as early as possible,” they conclude.
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