I read with interest the article by Salles and colleagues.1 While suboptimal therapy is the most common cause of resistant hypertension, secondary hypertension contributes up to 10% of hypertension referrals.2 In this recent article by Salles et al1 and in previous publications from this cohort, it is not mentioned whether secondary causes of hypertension were excluded. Furthermore, it is well known that patients with secondary causes of hypertension often have not only nocturnal hypertension but also excess cardiovascular morbidity and mortality, which could be related to secondary hypertension.3 If patients with secondary causes of hypertension were not excluded, it is possible that the relationship between nocturnal hypertension and cardiovascular outcomes could be confounded by metabolic and other processes associated with secondary hypertension, such as hyperaldosteronism, elevated angiotensin II level, diabetes, or renal dysfunction.
Kittisupamongkol W. Secondary Causes of Resistant Hypertension. Arch Intern Med. 2009;169(7):717. doi:10.1001/archinternmed.2009.30