The role of the alcohol biomarker PEth in hypertension management in primary care

<p dir="ltr">Background and aim</p><p dir="ltr">Alcohol increases the risk of developing hypertension and of blood pressure remaining poorly controlled. To prevent cardiovascular diseases and in the management of hypertension, a low alcohol intake is recommended. Patients with hypertension mainly receive their treatment in primary care. There are challenges in identifying hazardous alcohol use and for patients to reach a well-controlled blood pressure. The use of the alcohol biomarker PEth has increased in primary care, including in the management of hypertension. However, there is limited knowledge regarding the consequences of using PEth in primary care. The overall aim of this thesis was to investigate the implications of using PEth in hypertension management in primary care. The specific aims of the four studies were to: Explore patients' and general practitioners' experiences of PEth; describe alcohol consumption through PEth, Alcohol Use Disorders Identification Test (AUDIT), Alcohol Use Disorders Identification Test-Consumption (AUDIT-C), and alcohol history in relation to blood pressure control; and, finally, to examine the documentation of alcohol consumption and assess its association with blood pressure control, sex, age, and comorbidities.</p><p dir="ltr">Material and methods</p><p dir="ltr">Study I comprised five focus groups with GPs (n = 12) from different parts in Sweden, using an interview guide and qualitative content analysis. Study II was an observational cross-sectional study including 270 patients aged 30-85 years with hypertension from three primary care centres in Region Stockholm. Participants were stratified into three categories of blood pressure control: controlled, uncontrolled, and apparent treatment-resistant hypertension (aTRH). Alcohol consumption was assessed using the biomarker PEth 16:0/18:1, AUDIT, and AUDIT-C in relation to blood pressure control. Correlations between PEth and AUDIT, and between PEth and AUDIT-C were calculated. Study III was an observational cross-sectional study based on data from electronic medical records from 1,826 patients with hypertension at a primary care centre in Region Dalarna routinely using PEth. Documentation of alcohol consumption, with alcohol history and PEth, and its association with blood pressure control, sex, age, and comorbidities was examined. Additionally, proportion of patients with hazardous alcohol use, with PEth and alcohol history, in relation to BP-control was described. Study IV involved semi-structured telephone interviews with patients (n = 13) with hypertension from three Swedish primary care centres located in three regions in Sweden: Stockholm, Dalarna, and Kalmar. A topic guide was used, and the data were analysed with Grounded Theory.</p><p dir="ltr">Results</p><p dir="ltr">The overarching theme in Study I, "I don't hesitate anymore", captured how GPS had overcome their initial concerns that patients might react negatively to the use of PEth and instead experienced that its benefits outweighed potential drawbacks. This overarching theme encompassed four subthemes: 1) Serving as an eye-opener, 2) Improving the dialogue, 3) Using with care, and 4) Learning by doing.</p><p dir="ltr">Results from study II showed that the proportion of individuals with high and regular alcohol consumption, based on PEth, was approximately three times higher in the group with aTRH compared with those with controlled (p = 0.027) or uncontrolled (p = 0.013) blood pressure, whereas AUDIT did not identify differences between the blood pressure groups (p = 0.865). The correlation between PEth and AUDIT-C was somewhat higher than that observed between PEth and AUDIT. Overall, AUDIT-C identified a slightly higher proportion of individuals with hazardous alcohol use (≥4 points for women, ≥5 for men) than PEth (>0.122 umol/L): 28.6% versus 22.9%. Hazardous alcohol use identified with AUDIT was 12.4% in the overall study population. Hazardous alcohol use could be identified using PEth, AUDIT, and AUDIT-C alcohol across all levels of blood pressure control.</p><p dir="ltr">The results from Study III showed that, across the overall study population, alcohol consumption was documented twice as often using PEth (31.2%) compared with alcohol history (15.1%). Documentation varied by blood pressure group, age, sex, and certain comorbidities. Patients in the groups with uncontrolled blood pressure or aTRH were more likely to lack documentation of alcohol consumption (31.4 % and 31.6% respectively) than those in the group with controlled blood pressure (24.1%) (p = 0.00). PEth was slightly more commonly documented in younger patients and in those without diabetes. In the overall study population, the prevalence of hazardous alcohol use was 18.4% when defined as PEth (>0.122 umol/L), compared with 7.1% as identified with alcohol history (≥ 10 standard units of alcohol per week). No significant difference was observed in the prevalence of hazardous alcohol use among the three blood pressure control groups.</p><p dir="ltr">The main result from study IV was the theory "Double-layered insight". Four categories underpinned the main result: 1) Personal concern and agency, 2) Trusting the healthcare system to deliver, 3) Losing trust, and 4) Empowered by insight. Actions by both patient and GP influenced whether the patient lost trust or felt empowered. PEth provided objective information which could be uncomfortable but was generally perceived as meaningful. Transparency regarding PEth and non-judgmental dialogues were crucial for promoting motivation. PEth could be the only factor initiating a dialogue about alcohol.</p><p dir="ltr">Conclusion</p><p dir="ltr">PEth emerged as a valuable complement to established methods for assessing alcohol consumption in patients with hypertension in primary care, especially in the group with aTRH. PEth provided objective information and improved the interaction between the patient and the GP. The highest prevalence of hazardous alcohol use was identified using AUDIT-C. However, PEth indicated a higher prevalence of hazardous alcohol use compared with AUDIT and alcohol history. Hazardous alcohol use could be identified, with the four methods, across all groups of blood pressure control. PEth has influenced documentation practices, yet alcohol consumption remained least documented in patients with uncontrolled blood pressure and aTRH, indicating missed opportunities for risk identification in clinically vulnerable groups. PEth could both challenge and empower patients. Respect for patient autonomy and a non-judgmental dialogue appeared to be crucial for patients' acceptance of PEth testing and for preserving trust in the GP.</p><h3 dir="ltr">List of scientific papers</h3><p dir="ltr">I. <b>Thurfjell Å,</b> Sandlund C, Adami J, Hasselström J, Hagströmer M, Lundh L. GPs' experiences of Phosphatidylethanol in treatment of hypertension: a qualitative study. BJGP Open. 2023; 7 (4). <a href="https://doi.org/10.3399/BJGPO.2023.0037">https://doi.org/10.3399/BJGPO.2023.0037</a></p><p dir="ltr">II. <b>Thurfjell Å,</b> Hagströmer M, Ivarsson C, Norrman A, Adami J, Lundh L, Hasselström J. Hypertension and alcohol: a cross-sectional study comparing PEth with AUDIT and AUDIT-C in primary care. Family Practice. 2026; 43(1). <a href="https://doi.org/10.1093/fampra/cmaf097">https://doi.org/10.1093/fampra/cmaf097</a></p><p dir="ltr">III. Norrman A, <b>Thurfjell Å,</b> Hagströmer M, Adami J, Lundh L, Hasselstrom J. Comparing the documentation of Phosphatidylethanol and alcohol history in hypertension management in primary care: a cross-sectional study. [Manuscript]</p><p dir="ltr">IV. <b>Thurfjell Å,</b> Hagströmer M, Adami J, Hasselström J, Lundh L. Patients' experiences of Phosphatidylethanol in hypertension treatment in primary care: qualitative study. BJGP Open. <a href="https://doi.org/10.3399/BJGPO.2025.0201">https://doi.org/10.3399/BJGPO.2025.0201</a></p>