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Resistant and refractory hypertension

TL;DR — Most apparent treatment resistance is not resistance. Pooling 91 studies and 3,207,911 treated hypertensive patients gave apparent treatment-resistant hypertension in 14.7% (95% CI 13.1–16.3), pseudo-resistance in 10.3% (6.0–15.5) and true resistance in 10.3% (7.6–13.2) — with true resistance reaching 22.9% (19.1–27.0) in chronic kidney disease and 56.0% (52.7–59.3) in renal transplant recipients (Noubiap 2019, PMID 30087099). A 2026 review puts the filtering explicitly: of apparent resistant hypertension, about 37.5% is white-coat effect, about 50% involves medication non-adherence, and 5–25% is primary aldosteronism, leaving roughly 10% of all treated patients with true resistance (Azizi 2026, PMID 41870448). Once pseudo-resistance is excluded, spironolactone is the best-evidenced fourth agent: −8.70 mm Hg home systolic pressure versus placebo (95% CI 7.69–9.72) and −4.26 mm Hg (3.38–5.13) versus the mean of bisoprolol and doxazosin in PATHWAY-2's crossover design (Williams 2015, PMID 26414968). Newer options — aldosterone synthase inhibition, endothelin antagonism, renal denervation — all produce additional reductions in the 4–10 mm Hg range, none yet with hard-endpoint data.

Definitions and their consequences

Term Definition Note
Apparent treatment-resistant hypertension Office BP above target on ≥3 antihypertensive classes at maximally tolerated doses, ideally including a diuretic Based on office readings alone; over-counts
Pseudo-resistance Apparent resistance explained by white-coat effect, non-adherence, measurement error, or inadequate regimen ~10.3% of treated patients (Noubiap 2019, PMID 30087099)
True resistant hypertension Above-target out-of-office BP with confirmed adherence and an adequate regimen ~10.3% of treated patients (Noubiap 2019, PMID 30087099)
Refractory hypertension Uncontrolled on ≥5 agents including a mineralocorticoid receptor antagonist and a long-acting diuretic A distinct, more sympathetically driven phenotype (Modolo 2015, PMID 25979412)
Controlled resistant hypertension At target but requiring ≥4 drugs Carries residual risk and is often omitted from prevalence counts

Definitional variability is not pedantry — prevalence estimates differ by a factor of two or more depending on whether out-of-office measurement, adherence testing or both are required, and 70% of the 91 studies in the largest meta-analysis used office measurement alone (Noubiap 2019, PMID 30087099). Reviews set out the contested boundaries (Filippone 2024, PMID 37832756; Moreno 2022, PMID 35466494; Chernova 2019, PMID 31471727; Schiffrin 2024, PMID 38897628; Camafort 2024, PMID 38135468).

Excluding pseudo-resistance

White-coat effect. Ambulatory or home monitoring reclassifies a large fraction of apparent resistance — around 37.5% by one estimate (Azizi 2026, PMID 41870448). The white-coat effect in this population is not benign: it independently predicted myocardial ischaemia in resistant hypertension (Modolo 2014, PMID 24571101). Home monitoring has a defined role (Kim 2023, PMID 36641498), and the ambulatory profile of resistant hypertension has been characterised (de la Sierra 2013, PMID 23595047; Lazaridis 2015, PMID 26277726).

Non-adherence. Meta-analysis of 24 studies in apparent treatment-resistant hypertension gave pooled non-adherence of 31.2% (95% CI 20.2–44.7), with a range of 3.3–86.1% driven mainly by the assessment method — self-report and pharmacy records give much lower estimates than mass-spectrometry bioassay or directly observed therapy (Durand 2017, PMID 28777133). A 2025 synthesis of 70 chemical-adherence-testing papers gave pooled complete non-adherence 15.0% and any non-adherence 33.0% (I² 94.6% and 95.6%), and noted that testing has been done overwhelmingly in tertiary care and in predominantly White populations, so its generalisability is unknown (Highton 2025, PMID 40371625). Biochemical screening for non-adherence is itself an intervention: it was associated with blood-pressure reduction and improved adherence in one series (Gupta 2017, PMID 28847892), and routine urinary detection has been implemented at scale (Hamdidouche 2017, PMID 28505066). Psychological profile predicts both adherence and apparent resistance (Petit 2018, PMID 29952236; Georges 2022, PMID 36225118). Note the important negative: masked uncontrolled hypertension — normal office, high out-of-office pressure on treatment — is not explained by non-adherence (Siddiqui 2019, PMID 31327263), so the two phenomena require different responses.

Secondary causes. Primary aldosteronism accounts for 5–25% of resistant hypertension depending on the criteria used (Azizi 2026, PMID 41870448), and biochemically overt disease was present in 22.0% (95% CI 17.2–26.8) of a resistant-hypertension cohort tested systematically (Brown 2020, PMID 32449886). Obstructive sleep apnoea, chronic kidney disease and drug-induced hypertension complete the differential — see secondary hypertension and (Jurca 2016, PMID 27671491; Wei 2018, PMID 29905926).

Prognosis

Resistant hypertension carries substantially higher cardiovascular risk than controlled hypertension: an absolute increase in cardiovascular death of 10.3% (95% CI 8.7–12.1) at 5–10 years (Azizi 2026, PMID 41870448). Combining apparent resistance with poor adherence identifies a group with a distinctly worse prognosis in national cohort data (Lee 2025, PMID 39543414). In ALLHAT, outcomes among people meeting treatment-resistance criteria differed by randomised initial drug (Bangalore 2017, PMID 27984005).

Treatment

Optimise before escalating

Guideline-concordant sequencing — a renin-angiotensin blocker, a calcium channel blocker and a thiazide-type diuretic at maximally tolerated doses — plus substitution of chlorthalidone for hydrochlorothiazide, sodium restriction below about 1,500 mg/day, alcohol reduction, ≥150 min/week aerobic activity, weight loss, and removal of pressor drugs are first steps (Azizi 2026, PMID 41870448). Single-pill combinations of 2–3 agents lowered systolic pressure by 3.99 mm Hg (95% CI 0.07–7.92) more than the same doses given separately in meta-analysis of 20 studies, presumably through adherence (Azizi 2026, PMID 41870448) — see pharmacological therapy.

Fourth agent

PATHWAY-2 randomised 335 patients with resistant hypertension in a double-blind, four-way crossover through spironolactone (25–50 mg), bisoprolol (5–10 mg), doxazosin MR (4–8 mg) and placebo for 12 weeks each. Averaged home systolic reduction with spironolactone was 8.70 mm Hg better than placebo (95% CI 7.69–9.72), 4.26 mm Hg better than the mean of the other two actives (3.38–5.13), 4.03 mm Hg better than doxazosin and 4.48 mm Hg better than bisoprolol; superiority was greatest at low plasma renin but present across the renin distribution; serum potassium exceeded 6.0 mmol/L once in 6 of 285 spironolactone-treated patients (Williams 2015, PMID 26414968). The mechanisms substudies showed that spironolactone's advantage tracked sodium retention and that amiloride was similarly effective, supporting the sodium-retention hypothesis directly (Williams 2018, PMID 29655877). Network meta-analysis of 24 randomised trials in 3,485 patients gives spironolactone 25–50 mg/day (in those with eGFR ≥45 mL/min/1.73 m² and potassium ≤4.5 mmol/L) −13.3 mm Hg office systolic (95% CI −17.89 to −8.72) and −8.46 mm Hg 24-hour ambulatory systolic (−12.54 to −4.38) versus placebo (Azizi 2026, PMID 41870448). Eplerenone is an alternative where anti-androgenic effects are limiting (Manolis 2019, PMID 30826898).

Newer pharmacology

Agent Trial Effect
Aprocitentan (dual endothelin antagonist) PRECISION, 730 randomised (PMID 36356632) Office systolic −3.8 mm Hg (97.5% CI −6.8 to −0.8) at 12.5 mg and −3.7 (−6.7 to −0.8) at 25 mg vs placebo at 4 weeks; 24-h ambulatory −4.2 and −5.9 mm Hg; withdrawal at week 40 raised office systolic by 5.8 mm Hg (3.7–7.9); oedema/fluid retention 9%/18% vs 2%
Baxdrostat (aldosterone synthase inhibitor) Phase 2 (PMID 36342143); BaxHTN phase 3 (PMID 40888730); Bax24 ambulatory (PMID 41794437) Dose-dependent reductions; approved 2026 (Blair 2026, PMID 42625106)
Lorundrostat Target-HTN (PMID 37690061), phase 2 (PMID 40267417), Launch-HTN (PMID 40587141) Consistent reductions in uncontrolled and resistant hypertension
Renal denervation Meta-analysis of 10 sham-controlled RCTs, 2,478 participants (PMID 41870448) 24-h ambulatory systolic −4.4 mm Hg (95% CI −6.1 to −2.7); office −6.6 (−9.7 to −3.6)

Aprocitentan's oedema signal is the main tolerability limitation, and its effect size, while statistically robust and sustained through a randomised withdrawal, is modest (Schlaich 2022, PMID 36356632; Naseralallah 2024, PMID 39520722; Nguyen 2025, PMID 40638911). Ambulatory-derived variables have been analysed separately (Schlaich 2026, PMID 41195725). Broader reviews of the emerging resistant-hypertension pharmacopoeia are cautious (Nardoianni 2024, PMID 38616212; Zoccali 2024, PMID 38186891).

Devices

Renal denervation has its own history and page — see device and interventional therapy. Its aggregate effect in sham-controlled trials (24-hour ambulatory systolic −4.4 mm Hg) is comparable to aprocitentan's and smaller than spironolactone's (Azizi 2026, PMID 41870448), which frames it as an option for people who cannot take or tolerate a mineralocorticoid receptor antagonist rather than as a first escalation. Intensive blood-pressure targets have been examined specifically in the resistant subgroup of STEP (Dong 2026, PMID 40796327).

Special settings

Resistant hypertension in dialysis has distinct epidemiology and management (Georgianos 2024, PMID 38227447), and in chronic kidney disease generally the prevalence of true resistance is more than double the general figure (Noubiap 2019, PMID 30087099; Burnier 2023, PMID 37053276). Fasting and microbiome-directed interventions are at the exploratory stage (Yun 2025, PMID 40701347).

Open questions

  • Given that roughly half of apparent resistance involves non-adherence detectable only by chemical testing (Durand 2017, PMID 28777133; Highton 2025, PMID 40371625), should adherence testing precede any escalation to device therapy? The 2026-09-01 PubMed and ClinicalTrials.gov searches located adherence-testing studies and device trials separately, but no trial randomising that sequence.
  • Should primary aldosteronism be excluded in every case of resistant hypertension before spironolactone is started, or is empirical mineralocorticoid receptor antagonism an acceptable and cheaper substitute for diagnosis? (Brown 2020, PMID 32449886; Adler 2025, PMID 40658480)
  • Spironolactone's benefit is greatest at low renin but present throughout the renin range (Williams 2015, PMID 26414968). Renin-guided selection was prospectively compared with aldosterone-antagonist care in a 44-patient primary-care pilot: pressure reduction was similar, control was 62.5% versus 25%, and fewer drugs were added with renin guidance (Egan 2016, PMID 27076600). The unresolved question is whether that signal replicates in an adequately powered, patient-randomised trial with clinical outcomes; SPIRO-First is registered but not yet recruiting (NCT07687160).
  • The 2026-09-01 searches located no completed cardiovascular-outcome trial of a drug specifically for resistant hypertension; published aprocitentan, baxdrostat and lorundrostat trials remain pressure-based (Schlaich 2022, PMID 36356632; Flack 2025, PMID 40888730). Is an outcome trial feasible in a population this heterogeneous?
  • Refractory hypertension (≥5 drugs) is described as a sympathetically driven phenotype distinct from resistant hypertension (Modolo 2015, PMID 25979412) — should it be the target population for denervation rather than resistant hypertension generally?

References

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