It was encouraging to observe the concordance of the recommendations for proper blood pressure measurement and lifestyle modifications across the CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] with the 2017 ACC/AHA guideline [22] and the 2018 ESC/ESH guideline [23]. Accurate measurement and recording of blood pressure are of utmost importance in order to accurately classify the level of blood pressure, to guide management of hypertension, and to ascertain blood-pressure-related cardiovascular risk [22]. Although measurement of blood pressure in the office settings is relatively easy, it is not redundant for the emphasis in the CPGs for proper techniques of measurement, since in real-world clinical practice, it is often performed without adequate attention to the specified preconditions required for a valid measurement, which could lead to misestimation of patients’ true level of blood pressure and prescription of unnecessary treatment [22, 23]. On the other hand, nonpharmacological lifestyle interventions are effective in lowering blood pressure for patients with hypertension, with the most important approaches being weight loss, sodium reduction, increased physical activity, increased consumption of vegetables and fruits, reduction in alcohol consumption, and smoking cessation [22, 23]. The recommendations of these lifestyle interventions were consistent across CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35], and thus complete concordance with the 2017 ACC/AHA guideline [22] and the 2018 ESC/ESH guideline [23].
The blood pressure targets for patients with hypertension had always been controversial since the publication of the 2017 ACC/AHA guideline [22] which issued a groundbreaking recommendation that the goal blood pressure for most of the patients with hypertension should be < 130/80 mm Hg, including those without comorbidity. However, the 2018 ESC/ESH guideline [23] did not concur with the 2017 ACC/AHA guideline where a primary goal blood pressure of < 140/90 mm Hg was still recommended for all patients with hypertension but without comorbidity. Likewise, the recommended blood pressure target for patients with hypertension but without comorbidity was divided across the CPGs for the management of hypertension in Southeast Asia. Specifically, the CPGs originated from Malaysia [30], Brunei [31], and Singapore [32] respectively, were concordant with the 2018 ESC/ESH guideline [27], and the CPGs originated from Thailand [33], Indonesia [34], and Vietnam [35] respectively, were concordant with the 2017 ACC/AHA guideline [22], on the goal blood pressure for patients with hypertension age 18–60 years without comorbidity. None of the CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] was concordant with the 2017 ACC/AHA guideline [22] on the goal blood pressure (< 130/80 mm Hg) for patients with hypertension age > 60 years but without comorbidity, but the CPGs originated from Malaysia [30], Brunei [31], Singapore [32], and Thailand [33], respectively, were concordant with the 2018 ESC/ESH guideline [23] on the goal blood pressure (< 140/90 mm Hg) for patients with hypertension age 60–80 years but without comorbidity. CPGs originated from Indonesia [34] and Vietnam [35] respectively, advocated different blood pressure targets (< 140/80 mm Hg) than that specified in either the 2017 ACC/AHA guideline [22] or the 2018 ESC/ESH guideline [23]. Nonetheless, these CPGs from Southeast Asia [30,31,32,33,34,35] did not provide the rationale as to their recommended blood pressure targets in these patient populations.
Undeniably, the totality of the existing evidence in patients with hypertension indicates a reduction in the risk of major cardiovascular events and cardiovascular mortality with more intensive blood pressure lowering relative to standard blood pressure lowering. Specifically, the systematic review and meta-analysis (n = 23,169) [36] performed to inform the 2017 ACC/AHA guideline [22], which included randomized controlled trials with a systolic blood pressure target of < 130 mm Hg compared with any higher systolic blood pressure target reported significant risk reduction for stroke (relative risk = 0.82; 95% CI 0.70–0.96) and major cardiovascular events (relative risk = 0.84; 95% confidence interval 0.73–0.99). Similarly, another meta-analysis [37] of all available randomized controlled trials (n = 613,815) which had been cited in the 2018 ESC/ESH guideline [23] observed that further reduction per 10 mm Hg in systolic blood pressure reduced the rate of major cardiovascular events and death, even in patients with baseline systolic blood pressure between 130 and 139 mm Hg, indicating benefit at achieved systolic blood pressure of < 130 mm Hg. However, a meta-analysis of randomized trials (n = 255,70) [38] also reported that permanent discontinuation of drug therapy owing to adverse effects was significantly higher in patients with hypertension who had been targeted to achieve lower blood pressure. Therefore, advocating more intensive blood pressure lowering has to be considered alongside the accompanying risk of treatment discontinuation due to adverse events, which may counterweigh the limited incremental risk reduction of major cardiovascular events, and such consideration was the rationale that the 2018 ESC/ESH guideline [23] still recommended a primary blood pressure target of < 140/90 mm Hg. The recommendations of goal blood pressure across the included CPGs of Southeast Asia [30,31,32,33,34,35] most probably did not consider the cost-effectiveness of different goals blood pressure; in order to better inform the clinical practice, the CPG developer groups should conduct local cost-effectiveness analyses to determine if more intensive blood pressure lowering relative to standard blood pressure lowering is cost-effective, to balance between potential cost saving associated with an incremental reduction in major cardiovascular events and additional cost that would be spent for clinical care used to maintain lower blood pressure, including treatment for adverse events.
CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] were concordant with the recommendations in both the 2017 ACC/AHA guideline [26] and the 2018 ESC/ESH guideline [27] that ACE inhibitors, ARBs, and calcium channel blockers as the options for initial first-line therapy for patients with hypertension and no comorbidity. These three classes of antihypertensive agents have proven ability to reduce blood pressure and cardiovascular events, with broad equivalence on the risk reduction of overall cardiovascular morbidity and mortality in meta-analyses [37, 39]. However, CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] were non-concordant with the recommendation of thiazide diuretics as an option for first-line therapy in the said population as specified in both the 2017 ACC/AHA guideline [22] and the 2018 ESC/ESH guideline [23]. The non-concordance was stemmed from the CPG originated from Brunei [31] which did not consider thiazide diuretics as an option for first-line therapy without rationale provided for their exclusion (thiazide diuretics as an option for second-line therapy); the remaining CPGs in Southeast Asia [30, 32,33,34,35] listed thiazide-type diuretics as one of the first-line options.
Nonetheless, a systematic review and meta-analysis (n = 247,006) [39] of head-to-head trials of various classes of antihypertensive agents found that the effects of all classes of antihypertensive agents (thiazide diuretics, calcium channel blockers, ACE inhibitors, and ARBs) were not significantly different on all evaluated outcomes, including the risks of stroke, cardiovascular disease, heart failure, cardiovascular death, and all-cause death, when their achieved blood pressure was equivalent. Indeed, thiazide diuretics were superior compared to all other classes of antihypertensive agents to reduce the risk of heart failure in patients with hypertension (relative risk = 0.83; 95% confidence interval 0.73–0.94) [39]. Likewise, the systematic review and meta-analysis (n = 152,379) [36] performed to inform the 2017 ACC/AHA guideline [22] which included head-to-head trials of different classes of antihypertensive agents reported that no other classes of antihypertensive agents (ie, calcium channel blockers, ACE inhibitors, and ARBs) were significantly better than thiazide diuretics as the first-line therapy for the following evaluated outcomes: thiazide diuretics were associated with a significantly lower risk for heart failure relative to calcium channel blockers; significantly lower risk for cardiovascular events and stroke relative to ACE inhibitors; and significantly lower risk for cardiovascular events relative to calcium channel blockers.
Whether beta-blockers should be included as one of the options for initial first-line therapy for patients with hypertension but without comorbidity is still debatable, with divided recommendations between the 2017 ACC/AHA guideline [22] and the 2018 ESC/ESH guideline [23]. The 2017 ACC/AHA guideline [22] did not include beta-blockers as one of the options for first-line therapy, which was followed suit in the CPGs originated from Brunei [31], Indonesia [34], and Vietnam [35], respectively; whereas the 2018 ESC/ESH guideline [23] included beta-blockers as one of the options for first-line therapy, which was followed suit in the CPGs originated from Malaysia [30], Singapore [32], and Thailand [33]. The CPG originated from Malaysia [30] particularly cited a 2017 systematic review [40] which reported that beta-blockers are effective in patients with hypertension < 60 years of age in terms of preventing death, stroke, or myocardial infarction (versus placebo and other antihypertensive agents) and thus they are highly reasonable first-line options in the treatment of hypertension for this population, although the CPG originated from Malaysia [30] itself did not specify the age of patients which beta-blockers should be listed as one of the first-line options. The CPG originated from Thailand [33] though acknowledged that beta-blockers may be inferior to other antihypertensive agents to reduce the risk of cardiovascular diseases, beta-blockers were still being listed as one of the options for first-line therapy due to their similar effects on blood pressure-lowering with other established first-line antihypertensive agents, including ACE inhibitors, ARBs, calcium channel blockers, and thiazide diuretics. The remaining CPGs in Southeast Asia [31, 32, 34, 35] did not provide a rationale for the inclusion or exclusion of beta-blockers as one of the options for first-line therapy.
The notion in the 2018 ESC/ESH guideline [23] that mortality and major cardiovascular outcomes were broadly similar with initial therapy using beta-blockers compared to other first-line antihypertensive agents including ACE inhibitors, ARBs, calcium channel blockers, and thiazide diuretics may not hold true with the currently available evidence. The meta-analysis [39] cited in the 2018 ESC/ESH guideline to justify the recommendation of beta-blockers as one of the initial first-line options for patients with hypertension but without comorbidity has been updated recently. The updated meta-analysis (n = 165,850) [41] which included hypertension trials reported significantly increased risks of stroke (relative risk = 1.21; 95% confidence interval 1.07–1.38), composite of stroke and cardiovascular diseases (relative risk = 1.09; 95% confidence interval 1.01–1.17), and all-cause mortality (relative risk = 1.06; 95% confidence interval 1.01–1.12) with beta-blockers as compared to other first-line antihypertensive agents. Nonetheless, although beta-blockers were listed as one of the options for first-line therapy in the 2018 ESC/ESH guideline, thiazide diuretics, ACE inhibitors, ARBs, and calcium channel blockers were being preferred over beta-blockers as first-line therapy for patients with uncomplicated hypertension [23].
The blood pressure cutoffs for the diagnosis of hypertension was perhaps the most robust debate in the domain of hypertension over the recent years; the 2017 ACC/AHA guideline [22] recommended diagnosis of hypertension based on the office (non-automated) systolic blood pressure reading of ≥ 130 mm Hg and/or diastolic blood pressure reading of ≥ 80 mm Hg, but the 2018 ESC/ESH guideline [23] did not follow suit and recommended the conventional cutoffs based on systolic blood pressure reading of ≥ 140 mm Hg and/or diastolic blood pressure reading of ≥ 90 mm Hg. Interestingly, none of the CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] followed the cutoffs recommended in the 2017 ACC/AHA guideline [22], including those [30, 31, 33,34,35] which are published later than the 2017 ACC/AHA guideline [22]; the conventional cutoffs (≥ 140/90 mm Hg) was still being recommended for practice. The developers of the CPG originated from Malaysia [30] believed that the new definition in the 2017 ACC/AHA guideline [22] would not change the way that patients with hypertension was treated, particularly those with cardiovascular complications and blood pressure of ≥ 130/80 mmHg who would need antihypertensive treatment regardless. In addition, the CPG originated from Vietnam [35] believed that the evidence was still insufficient to adopt the new definition recommended in the 2017 ACC/AHA guideline [22].
The notion that the evidence was insufficient with regard to the new cutoffs for diagnosis of hypertension recommended by the 2017 ACC/AHA guideline [22] was probably true since it was merely based on meta-analyses [24, 42,43,44,45,46,47,48,49,50,51,52] of observational data. The 2017 ACC/AHA guideline reviewed the available meta-analyses of observational studies [24, 42,43,44,45,46,47,48,49,50,51,52] and compared the reported hazards for cardiovascular events and stroke of different ranges of blood pressure with a blood pressure of < 120/80 mmHg: patients with a blood pressure of 120–129/80–84 mmHg was similarly at risk for cardiovascular events and stroke, with hazard ratios ranged between 1.1 to 1.5, compared to their counterparts with a blood pressure of 130–139/85–89 mmHg, with hazard ratios ranged between 1.5 to 2.0 [22]. However, the systematic review and meta-analysis [53] of randomized clinical trials with at least 1000 patient-years of follow-up cited in the 2018 ESC/ESH guideline [23] found significant risk reduction of death and cardiovascular events in patients with a baseline blood pressure of ≥ 140/90 mm Hg, while no observed benefits with lower baseline blood pressure. Therefore, it may be prudent to observe the impact in the management of hypertension in the United States of America with the new cutoff recommended in the 2017 ACC/AHA guideline [22] before the introduction of such cutoff in Southeast Asia. Despite not using the new cutoff proposed in the 2017 ACC/AHA guideline [22], all CPGs for the management of hypertension in Southeast Asia [30, 31, 33,34,35], except the CPG originated from Singapore [32], recommended consideration for antihypertensive drug treatment in patients who have the blood pressure of 130–139/80–89 mm Hg and elevated cardiovascular risk.
Detailed analysis of concordance of recommendations between the CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] and either the 2017 ACC/AHA guideline [22] or the 2018 ESC/ESH guideline [23] revealed that the justification for the non-concordant recommendations had been poorly described or had not been described at all in the CPGs in Southeast Asia [30,31,32,33,34,35]. This may be related to a lack of rigor in the construction of CPGs for the management of hypertension in Southeast Asia as previously reported [53]. We believe it might be a worthwhile option for the guideline development groups in Southeast Asia to adapt their recommendations from the existing high-quality CPGs based on formal adaptation frameworks (e.g., GRADE-ADOLOPMENT), as it helps to ensure that their recommendations stay true to the best available evidence while considering the local needs.
This study has some limitations. Firstly, only CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] published in an official (translated) language of English or Malay were included. Therefore, it was not known if the other versions of the included CPGs published in other official languages (e.g., Thai) had differences content-wise compared to the version of the CPGs published in an official (translated) language of English or Malay. Secondly, we only evaluated the concordance of recommendations in terms of their direction but without considering concordance in terms of their strength of evidence since not all of the included CPGs for the management of hypertension in Southeast Asia [30,31,32,33,34,35] adopted a formal consensus method to grade the level of evidence and/or strength of the formulated recommendations.
In conclusion, hypertension represents a significant issue that places health and economic strains in Southeast Asia and this demands guideline-based care, yet CPGs for the management of hypertension in Southeast Asia have a high rate of non-concordance with internationally reputable CPGs. Nonetheless, concordant recommendations could perhaps be considered a standard of care for hypertension management in the Southeast Asia region. Conversely, non-concordant recommendations should not be considered a true or stable standard of care, as these represent opposing standards from reputable sources which leave room for flexibility, and clinical autonomy should be used to individualize clinical decisions.