A new study by researchers at University of Limerick has found that control of high blood pressure in adults with chronic kidney disease (CKD) is ‘poor’.
This is significant, given that an estimated 400,000 patients in Ireland have chronic kidney disease and that hypertension, or high blood pressure, is a major risk factor for kidney failure, heart attacks and strokes.
The new study by researchers at University of Limerick School of Medicine has just been published in the Clinical Kidney Journal of the European Renal Association.
It is the largest study of its kind to explore the prevalence, awareness and management of hypertension in individuals with kidney disease using data from the Irish Longitudinal Study on Aging (TILDA).
It found that four out of five individuals (82 per cent) with chronic kidney disease in Ireland, age 50 and over, suffer from hypertension, and although the awareness of hypertension and treatment of hypertension are high, control of blood pressure (BP) is far from desired, with just under 50 per cent of individuals achieving a desired target.
The study revealed that the burden of hypertension was far more common in individuals with kidney disease than without (81.9% vs 59.7%), especially in men and in older individuals.
The investigators also found that individuals with chronic kidney disease and hypertension were more aware of their hypertension diagnosis than those who did not have kidney disease (70.1 vs 51.7%).
The research further revealed that individuals with hypertension and kidney disease were also more likely to be treated compared to those without kidney disease.
Among the key findings were:
- Prevalence of hypertension was extraordinarily high at 81.9 per cent and was much more common than in those without kidney disease.
- Patient awareness of hypertension was far higher in individuals with kidney disease than those without (70.1 vs 51.7%).
- A large proportion of patients with kidney disease were receiving antihypertensive medications (83.5 per cent).
- Two-thirds of patients with chronic kidney disease were receiving two or more blood pressure medications.
- Blood pressure control was poor, with only 49.3 per cent achieving a target <140/90mmHg.
- Blood pressure control was even poorer, with only 17.9 per cent achieving SBP <120mmHg.
The study was led by Dr Leonard Browne, Senior Research Fellow in Biostatistics, National Kidney Disease Surveillance System (NKDSS) at the UL School of Medicine.
He explained: “Hypertension is common in individuals with chronic kidney disease and a major risk factor for kidney failure, major cardiovascular events and death. Despite our best efforts using a wide variety of anti-hypertensive medications, achievement of blood pressure control in patients with kidney disease remains a major challenge.
“Our findings are in line with international studies and reveal that while there are high levels of awareness of hypertension, and high rates of treatment compared to individuals without kidney disease, we are not getting patients to desired targets associated with the best outcomes.”
Professor Austin Stack, senior author and Lead Investigator at NKDSS at UL’s School of Medicine and Consultant Nephrologist, University Hospital Limerick, explained: “Unfortunately, the high levels of awareness and treatment did not translate into better blood pressure control. The study shows that less than half of individuals with chronic kidney disease achieved a target blood pressure of 140 over 90, a target that has been set for the majority of patients for many years by the international scientific community.
“The results were markedly worse for individuals aged 75-plus years, where the per cent dropped to 42.4 per cent.
“Recently, there is evidence to suggest that more stringent control of blood pressure, targeting a lower systolic blood pressure < 120mmHg (rather than 140 mmHg) leads to greater clinical benefit for these patients by reducing further the risk of major cardiovascular events and death.
“However, when we applied this target to our study population, we found that just under 18 per cent of patients achieved this target. Although more stringent blood pressure control may be of benefit to many patients with chronic kidney disease, our data from TILDA with 5,356 individuals suggests that this target is only achievable in less than one-in-five patients.”
The researchers believe several factors contribute to suboptimal blood pressure control in patients with chronic kidney disease.
Dr Browne noted, “Non-adherence to medication is common among many patients, which may partially explain these findings. Additionally, some doctors may hesitate to prescribe additional blood pressure medications due to concerns about overtreatment, higher risk of falls, and ongoing controversy over blood pressure targets.”
“Our findings from TILDA revealed that 62 per cent of individuals with hypertension were receiving two or more antihypertensive medications, and this number reached 67 per cent in those age 75 and over. This implies that one-third of patients were treated with just a single blood pressure medication, leaving much room for improvement. The addition of a second or third antihypertensive medication is often a necessary step in these patients to ensure more effective blood pressure control along with lifestyle modification.”
