Effectiveness of blood pressure-lowering drug treatment by levels of absolute risk: post hoc analysis of the Australian National Blood Pressure Study

Abstract

ObjectivesIn many current guidelines, blood pressure (BP)-lowering drug treatment for primary prevention of cardiovascular disease (CVD) is based on absolute risk. However, in clinical practice, therapeutic decisions are often based on BP levels alone. We sought to investigate which approach was superior by conducting a post hoc analysis of the Australian National Blood Pressure (ANBP) cohort, a seminal study establishing the efficacy of BP lowering in ‘mild hypertensive’ persons.DesignA post hoc subgroup analysis of the ANBP trial results by baseline absolute risk tertile.Setting and participants3244 participants aged 35–69 years in a community-based randomised placebo controlled trial of blood pressure-lowering medication.InterventionsChlorothiazide500 mg versus placebo.Primary outcome measuresAll-cause mortality and non-fatal events (non-fatal CVD, congestive cardiac failure, renal failure, hypertensive retinopathy or encephalopathy).ResultsTreatment effects were assessed by HR, absolute risk reduction and number needed to treat. Participants had an average 5-year CVD risk in the intermediate range (10.5±6.5) with moderately elevated BP (mean 159/103 mmHg) and were middle aged (52±8 years). In a subgroup analysis, the relative effects (HR) and absolute effects (absolute risk reduction and number needed to treat) did not statistically differ across the three risk groups except for the absolute benefit in all-cause mortality (p for heterogeneity=0.04). With respect to absolute benefit, drug treatment significantly reduced the number of events in the high-risk group regarding any event with a number needed to treat of 18 (10 to 64), death from any cause with 45 (25 to 196) and major CVD events with 23 (12 to 193).ConclusionOur analysis confirms that the benefit of treatment was substantial only in the high-risk tertile, reaffirming the rationale of treating elevated blood pressure in the setting of all risk factors rather than in isolation.

Effectiveness of an Adult Food Literacy Program

“…This method has been used with population or patient groups in epidemiological and clinical studies to determine those more at risk of specific outcomes. When a specific cut off value is unknown, a defined variable is used to specify tertiles, where the population is split into three groups [37]. Variables such as biomedical scores, clinical tests or dietary intake are used to define the lowest tertile group, the group with the highest risk or poor outcomes associated with the low score.…”

Identifying Participants Who Would Benefit the Most from an Adult Food-literacy Program

“…This is an accepted method used in clinical and epidemiological studies to determine the patient or population subgroups most at risk when the cut-off is unknown. Tertiles of patient and population groups have been determined from variables such as clinical tests, biomedical scores and dietary intakes to derive the lowest tertile group and; therefore, identify the group most at risk of poor outcomes associated with low scores [44,45,46]. This approach was taken to identify those most at risk of low food literacy by determining which participants scored in the lowest tertile for food literacy, and then test associated variables.…”

Exclusively plant, whole-food diet for polypharmacy due to persistent atrial fibrillation, ischaemic cardiomyopathy, hyperlipidaemia and hypertension in an octogenarian

“…Current treatment guidelines for cardiovascular disease recommend both pharmaceutical therapy and lifestyle modifications, such as diet and physical activity 7 8. Yet commonly used medications provide low absolute risk reduction of cardiovascular events and all-cause mortality9 10 and pose significant risk of adverse events 11 12. Furthermore, most physicians feel inadequately trained to advise patients about food and eating behaviour,13 and less than half of primary care physicians routinely discuss diet with patients diagnosed with cardiovascular disease 14.…”