Psychological determinants of drug adherence and severity of hypertension in patients with apparently treatment-resistant vs. controlled hypertension.

Purpose: In a pilot study including 35 patients with apparently treatment-resistant hypertension (ATRH), we documented associations between psychological profile, drug adherence and severity of hypertension. The current study aims to confirm and expand our findings in a larger and more representative sample of patients with ATRH, using controlled hypertensive patients as the comparator.

Materials and methods: Patients with ATRH were enrolled in hypertension centres from Brussels and Torino. The psychological profile was assessed using five validated questionnaires. Drug adherence was assessed by high-performance liquid chromatography-tandem mass spectrometry analysis of urine samples, and drug resistance by 24-hour ambulatory blood pressure was adjusted for drug adherence.

Results: The study sample totalised 144 patients, including 81 ATRH and 63 controlled hypertensive patients. The mean adherence level was significantly lower in the "resistant" group (78.9% versus 92.7% in controlled patients, p-value = .022). In patients with ATRH, independent predictors of poor drug adherence were somatisation, smoking and low acceptance level of difficult situations, accounting for 41% of the variability in drug adherence. Independent predictors of severity of hypertension were somatisation, smoking, more frequent admissions to the emergency department and low acceptation, accounting for 63% of the variability in the severity of hypertension. In contrast, in patients with controlled hypertension, the single predictors of either drug adherence or severity of hypertension were the number of years of hypertension and, for the severity of hypertension, alcohol consumption, accounting for only 15-20% of the variability.

Conclusion: Psychological factors, mostly related to somatisation and expression of emotions are strong, independent predictors of both drug adherence and severity of hypertension in ATRH but not in controlled hypertensive patients.