Disease labels have an aura of authority and permanence. But definitions can drift considerably over time changing who is and is not classified as “diseased.” For hypertension, Greene [1] has nicely documented the steady lowering of the threshold over the past five decades, but we have kept the same label and same attitudes. It might be more truthful to say “you have hypertension version 3.1,” or perhaps we should drop the term altogether? Up until the 1950s “hypertension” was used for symptomatic patients, but most now labelled as hypertensive are asymptomatic, and the threshold BP has dropped steadily. But in asymptomatic patients we are concerned with cardiovascular risk and blood pressure is only one of several risk factors. Perhaps it is time to drop the individual risk factor arbitrary dichotomies (hypertension, hypercholesterolemia, obesity, and even diabetes), and focus on what patients are concerned about—cardiovascular risk.
At a satellite meeting of the International Society for Hypertension (perhaps a name change is overdue?) Rod Jackson argued we should abandon the term as it leads to mislabelling and mistreatment: over treatment of the low risk, and under treatment of the high risk. A blood pressure of 150/95 has a different meaning for a 45 year old women with no other risk factors, and a 55 year old male smoker with a cholesterol of 6.8 mmol/l. When we label low risk patients as “hypertensive,” there is an urge to start treatment, despite the recent Cochrane review [2] suggesting undetectable benefits in such patients. On the other hand, we are too complacent about “normal” blood pressure in patients after a myocardial infarction, TIA, or stroke. The last two particularly tend to still be under treated despite trials, such as PROGRESS [3], showing benefits for antihypertensives in patients after TIA or stroke, but with traditionally “normal” blood pressure. As Rod Jackson pointed out, the observational epidemiological studies show cardiovascular risk is lower with lower blood pressure, at least down to a systolic of 115 mm Hg. But reduction only becomes clearly worthwhile when combined risk is high enough.
We seemed to have moved halfway from single risk factors to a combined risk approach: we assess CVD risk, but continue to use single risk factor dichotomous labels, which can divert us from our real clinical task of lowering CVD risk in high risk patients. Anyone got a better term than “hyperCVDriskosis?”
References
1. Jeremy A Greene. Prescribing by Numbers: Drugs and the Definitions of Disease. Johns Hopkins Press, Baltimore 2007.
2. Diao D, Wright JM, Cundiff DK, Gueyffier F. Pharmacotherapy for mild hypertension. Cochrane Database Syst Rev. 2012
3. PROGRESS Collaborative Group. Randomised trial of a perindopril-based blood-pressure-lowering regimen among 6,105 individuals with previous stroke or transient ischaemic attack. Lancet. 2001;358:1033-41.
Paul Glasziou is professor of evidence based medicine at Bond University and a part-time general practitioner.
Declaration: PG was a member of the scientific committee of the ADVANCE trial which studied the impact of antihypertensives for diabetic patients irrespective of blood pressure.