The goal of this observational cross-sectional study is to map the prevalence of hazardous alcohol use in 270 adult patients with hypertension in Primary Health Care (PHC). The main question it aims to answer is: What is the prevalence of hazardous alcohol use in a population with hypertension in primary care detected with PEth and AUDIT, analysed in relation to patients with controlled, uncontrolled and treatment resistant hypertension? Participants will, in conjunction with annual control of hypertension with a General Practitioner (GP) at their Primary Health Care Centre (PHCC), visit a study nurse. The study nurse will collect following data: • Physical measurements• Lifestyle habits• Quality of life and demographic data • Drugs for hypertension and comorbidity • Laboratory tests including Phosphatidylethanol (PEth).

Hypertension, tobacco smoking, and alcohol use are the three leading risk factors for global disease burden. Treatment of hypertensive disease is important for the prevention of atherosclerotic disease, atrial fibrillation, heart failure, stroke, and dementia. In Sweden 27 % of adults have hypertension and a majority are treated in PHC but only 37 % reach target blood pressure. Alcohol can be one factor behind the low number of goal completion of blood pressure level.

Prevalence of hazardous alcohol use in Sweden is between 10-30 % in adults. Alcohol has an important role for over 200 diagnoses. There is a causal and dose dependent relationship between blood pressure levels and regular alcohol intake. Previous studies have reported hypertension to be attributable to alcohol in a wide range, depending on for example population, sex, and cultural context. But studies about the prevalence of hazardous alcohol use in patients with hypertension is few or even lacking.

General Practitioners (GPs) miss to identify a majority (60-70%) of patients with hazardous alcohol use even though guidelines on hypertension include risk stratification and detection of harmful lifestyle and the fact that general practitioners find it important to talk about alcohol with their patients.

Alcohol Use Disorders Identification Test (AUDIT) is a validated screening test for hazardous and harmful use in PHC setting, although concerns have been raised to its sensitivity. GPs experience that patient underestimate their consumption and that AUDIT does not meet the requirements to be a useful tool to detect hazardous alcohol use and AUDIT is seldomly used in PHC.

The alcohol biomarker Phosphatidylethanol (PEth) has high sensitivity and specificity to detect alcohol use. PEth can detect chronic heavy consumption. PEth is one of the newest alcohol biomarkers, but despite promising characteristics of PEth it is not routinely applied in clinical practice. PEth is used in a variety of settings like addiction care, emergency rooms, treatment of HIV-patients and patients with liver disease. PEth has started to be used in PHC but few studies on the use of biomarkers for alcohol consumption have been carried out in PHC.

The Swedish National Board of Health and Welfare has presented methods to use for supporting patients to change hazardous alcohol use. First the GPs need to identify if the patient has hazardous alcohol use. To our knowledge studies on whether PEth is a useful tool to detect hazardous use in patients with hypertension, in a primary health care context, is scarce or missing.

Study design

Based on that 12% of the hypertensive patients is related to alcohol intake and a presumed prevalence of hazardous drinking of 15 % the required sample size, given an effect size of 21%, significance level 5%, and power of 80% using contingency tables with 2 degrees of freedom, the study will require 270 patients with an included 10 % to compensate for missing values.

To perform an effective recruitment of patients we will invite patients from three well-functioning PHCCs with approximately 15.000 listed patients. Criteria for well-functioning is stable management and staff, routines for handling hypertension as well as unhealthy life-style habits and ability to offer locals for the project. By using the tool Medrave4 all patients 30-85 years old with hypertension (ICD-10 diagnose code I10.9) will be extracted from the PHCCs. The patients will be stratified to three groups of hypertension: •Controlled (blood pressure < 140/90), •Uncontrolled (blood pressure ≥ 140/90) and, •Treatment resistant hypertension (≥ 140/90 with three or more drugs against hypertension). Strata groups will be randomised, and the patients will be invited top to bottom. Recruitment will stop when 30 patients from each group has been included.

The PHCCs operations manager invites patients by letter. Patients have the opportunity to register their interest in participating in the study by letter or phone. Patients can also notify that they do not wish to be contacted. After 2-3 weeks the study nurse calls the patients and ask if they want to participate. The study nurse makes an initial assessment of the inclusion and exclusion criteria over the phone.

At the visit with the study nurse the final assessment of inclusion and exclusion criteria will be made. Finally the patients will be included after written informed consent. At the visit following data will be collected and stored at the digital platform REDCap:• Physical measurements (Blood pressure, pulse, weight, height, and waist measurement) • Lifestyle habits ( Alcohol, tobacco, food, and physical activity) • Quality of life (EQ-5D-5L) •Comorbidity with relevance to hypertension (Diabetes type 1 or 2, atrial fibrillation, angina pectoris, heart failure, myocardial infarction, stroke, and Transient ischemic attack) • Socioeconomic data (year of birth, gender, education, employment, occupation, people in the household) • Drugs for hypertension (Beta blockers, Calcium blockers, Thiazides, ACE inhibitors, ARB blockers, and Potassium-sparing diuretic) • Blood- and urine tests for hypertension and Phosphatidylethanol (PEth).

Patients will then visit their GP for an usual annual control of hypertension. The patients will receive results of blood tests and if needed adjustment of treatment will be done. Study nurse and GPs will talk about life style factors, including alcohol, with the patient. If hazardous alcohol use they will give short advice and offer more support if the patient needs and wants it. Before the start of the study GPs from the PHCCs will attend a short education of how to interpret PEth and AUDIT.

Detection of hazardous alcohol use, by the two methods PEth and AUDIT, will be described in the three strata (controlled, uncontrolled and treatment resistant hypertension) of the whole cohort. We will adjust for possible confounders (lifestyle factors, socio-economic data and patients' perceived health). We will relate our calculations to established risk stratification models for cardiovascular disease. All patients with hypertension and the drop-out population will be analysed according to what is ethically possible. Usual statistical presentation methods based on the scale level of collected data and other properties will be used.

Inclusion Criteria:

• Hypertension ICD-10 code I10.9.
• Age 30-85 years.

Exclusion Criteria:

• Not able to come to the primary health care centre
• Not understanding swedish
• Not speaking swedish
• Severe disease
• Dementia
• Serious mental illness

From 2-3 PHCCs, in Stockholm region in Sweden, we will find patients with the extraction tool Medrave4. Patients with hypertension from the last two years will be extracted and the criteria for inclusion will be applied. A stratified and random sample will be created of three different groups of hypertension: Controlled, Uncontrolled and, Treatment resistant hypertension.