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. Plain language summary This study included 144 patients with Apparently-Treatment Resistant (ATRH) or controlled Hypertension: Patients with ATRH were more often poorly adherent to antihypertensive treatment than controlled hypertensive patients. In patients with ARTH but not patients with controlled hypertension, psychological traits were strong, independent predictors of drug adherence and severity of hypertension, over and above demographic and health-related factors. In patients with ATRH, the tendency to somatize, i.e. expressing somatic symptoms that cannot be adequately explained by organic findings was the most potent predictor of both poor drug adherence and severity of hypertension. These patients also often presented alterations in the expression of emotions. It may be hypothesised that subjects who have difficulties identifying and expressing emotions with words will express them by physical complaints, and, in the mid-long term, might develop overt diseases. In addition to more classical lifestyle and drug management and irrespective of their drug adherence level, patients with ATRH may benefit in priority from psychological evaluation and interventions. However, this needs to be studied in an interventional trial in the future.