Adopting Systolic Pressure Intervention Trial (SPRINT)-like office blood pressure measurements in clinical practice

In this issue of the Journal of Hypertension Leenen et al.[1] report the percentage of high blood pressure (BP) control obtained, about 10 years ago, in a sample representative of the Ontario (Canada) population, in which BP was measured in a fashion similar to that employed in the hypertensive patients of the Systolic Pressure Intervention Trial (SPRINT) [2]. That is, by averaging several values obtained via a semiautomatic measuring device in individuals left alone in a room for several minutes, a procedure shown to be unaffected by the alerting response and the rise that characterize BP when measured by or in the presence of healthcare responsible personnel [3–5]. The results show that this BP measuring approach is associated with a strikingly high number of treated patients in whom BP control is achieved. They further show that control is extremely common (>80% of the treated population) when, as recommended by guidelines [6–8], the target for treatment is set at less than 140/90 mmHg (SBP/DBP). It is also quite frequently achieved when a lower target (i.e. <130/80 mmHg) is adopted, a goal supported by some guidelines [9] in few clinical conditions (diabetes and proteinuric nephropathy), but usually regarded as so hard to reach as to have a limited practical value [10]. Interestingly, the low unattended semiautomatic BP values obtained in SPRINT by intense treatment were frequently seen also in the elderly fraction of the hypertensive population, somewhat unexpectedly without requiring, unlike in SPRINT [2], the administration of two or, in most patients, three antihypertensive agents. In the population survey of Leenen et al.[1] treated and controlled hypertensive patients exhibited a BP far lower than 140/90 mmHg (about 120/70–75 mmHg), although receiving only one antihypertensive drug in the majority (51%) of the cases, those under a three-drug regimen being only 14%. Two or three drug administration was more common in the most advanced age stratum (70–79 years) in which, however, one drug administration continued to be successfully prescribed in about one-third of the patients. This last set of data attenuates the concern that adoption of the low BP target shown to be beneficial in the SPRINT trial would wipe out antihypertensive monotherapy, making multiple antihypertensive drug administration the only strategy to be used, with a possible increase in therapeutic costs, drug-related side-effects and treatment discontinuation. Indeed, that the low BP values pursued by SPRINT can be frequently achieved in the real world setting without a substantial increase in the complexity of the prescribed treatment regimen provide guidelines that will decide to adopt the SPRINT BP values as a target for treatment with the important information that in clinical practice this may meet with less therapeutic difficulties and more success than it might be expected. The observations of Leenen et al.[1] may strengthen the position of those who advocate ‘SPRINT-like’ office BP measurements on a routine basis, a switch from the time-honoured conventional BP measuring approach that is opposed, however, by several counterarguments. First, several results of the SPRINT trial are not easy to be interpreted making further discussion of its results and confirmation by additional trials desirable [11]. Second, as discussed below, SPRINT-like BP measurements have an uncertain quantitative relationship with the conventional office BP measurement approach that has extensively documented the protective effects of treatment-dependent BP reductions [12]. Third, the SPRINT-like BP measurement approach is more time consuming and expensive than the conventional one. It requires prolongation of the medical visit well beyond its usual duration in most countries. It needs a wider space to allow patients to be kept alone and undisturbed. It necessitates a number of BP measuring devices, which may increase diagnostic costs. Finally, limited information is available on whether unattended semiautomatic office BP is a marker of the BP-dependent risk at least as good as the attended office values, whose prognostic ability is, in contrast, documented by a huge number of studies in untreated and treated individuals [13,14]. In a recent observational investigation, also performed in Canada, semiautomatic unattended diastolic BP did not bear any relationship with outcomes, a relationship with SBP being observed only below 120 and above 150 mmHg [15]. This suggests a limited prognostic sensitivity within a BP range where most of the treated patients lay. Another aspect of the Ontario survey performed by Leenen and coworkers [1] deserves a comment. Namely that its data should not be inappropriately interpreted as to mean that in the hypertensive population an effective BP reduction is common rather than rare, the consensus that poor BP control is a main factor opposing cardiovascular prevention thus originating from a misconception. This is because the BP data obtained in the Ontario population are lower than those from which the extent of population-based hypertension control have been derived, all of which based on measurements performed in attended patients and thus with a white-coat effect [12]. Although, believed to amount to only a few mmHg by some investigators [16], it seems possible that larger differences divide these measuring approaches. Intraarterial ambulatory BP monitoring studies, for example, have shown that during a doctor's visit mean arterial pressure increased by an average of about 17 mmHg [4,5]. Furthermore, in a recent study a 15 mmHg difference between attended manual and unattended semiautomatic SBP measurements has been reported [17]. This suggests that major correction factors need to be applied to the unattended semiautomatic office BP to make them confrontable with the target BP recommended by guidelines. Information from studies measuring both conventional and SPRINT-like office BP in large groups of patients with different demographic and clinical characteristics, will be needed to achieve this goal. Alternatively, hypertension control will have to be quantified by comparing unattended semiautomatic office BP values with the lower target BP values established in outcome trials by the same BP measuring approach. This will require confirmation of the SPRINT results as well as their extension to clinical conditions that SPRINT did not explore. ACKNOWLEDGEMENTS Conflicts of interest There are no conflicts of interest.

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