Uncontrolled and apparent treatment resistant hypertension: a cross-sectional study of Russian and Norwegian 40-69 year olds.

Background: Uncontrolled hypertension is a major cardiovascular risk factor. We examined uncontrolled hypertension and differences in treatment regimens between a high-risk country, Russia, and low-risk Norway to gain better understanding of the underlying factors.

Methods: Population-based survey data on 40-69 year olds with hypertension defined as taking antihypertensives and/or having high blood pressure (140+/90+ mmHg) were obtained from Know Your Heart Study (KYH, N = 2284), Russian Federation (2015-2018) and seventh wave of The Tromsø Study (Tromsø 7, N = 5939), Norway (2015-2016). Uncontrolled hypertension was studied in the subset taking antihypertensives (KYH: N = 1584; Tromsø 7: 2792)and defined as having high blood pressure (140+/90+ mmHg). Apparent treatment resistant hypertension (aTRH) was defined as individuals with uncontrolled hypertension on 3+ OR controlled on 4+ antihypertensive classes in the same subset.

Results: Among all those with hypertension regardless of treatment status, control of blood pressure was achieved in 22% of men (KYH and Tromsø 7), while among women it was 33% in Tromsø 7 and 43% in KYH. When the analysis was limited to those on treatment for hypertension, the percentage uncontrolled was higher in KYH (47.8%, CI 95 44.6-50.9%) than Tromsø 7 (38.2, 36.1-40.5%). The corresponding figures for aTRH were 9.8% (8.2-11.7%) and 5.7% (4.8-6.8%). Antihypertensive monotherapies were more common than combinations and used by 58% in Tromsø 7 and 44% in KYH. In both KYH and Tromsø 7, untreated hypertension was higher in men, those with no GP visit in the past year and problem drinkers. In both studies, aTRH was associated with older age, CVD history, obesity, and diabetes. In Tromsø 7, also male gender and any drinking. In KYH, also chronic kidney disease.

Conclusion: There is considerable scope for promoting combination therapies in line with European treatment guidelines in both study populations. The factors associated with untreated hypertension overlap with known correlates of treatment non-adherence and health check non-attendance. In contrast, aTRH was characterised by obesity and underlying comorbidities potentially complicating treatment.