Redefining Optimal Phosphatidylethanol (PEth) Cutoffs for Alcohol Screening (ROCS) - Unhealthy alcohol use, which ranges from exceeding cutoffs for moderate drinking to severe alcohol use disorder, is often unrecognized due to patient under-reporting and low utilization, despite longstanding recommendations for yearly screening. A blood-based alcohol biomarker, phosphatidylethanol (PEth), that reflects the total volume of alcohol consumed in the prior 2-4 weeks, may improve detection of unhealthy alcohol use, aid in appropriately targeting interventions to drinking level, and motivate behavior change. PEth tests are currently available at major commercial laboratories and could be incorporated into routine lab testing, along with standard tests such as cholesterol. However, there is no established PEth cutoff for unhealthy alcohol use, while there are consensus cutoffs for very low and very high levels of alcohol consumption. Previous investigations of PEth cutoffs have mostly relied on retrospective self-report about alcohol consumption over weeks or months, which has been shown to have many limitations. Also, while some studies have shown PEth levels may be affected by sex and body mass index (BMI), characteristics known to affect alcohol metabolism, current PEth cutoffs do not account for these. In addition, we lack data on the extent of under-reporting in primary care screening. Thus, the potential gains to be made by utilizing PEth-based screening in primary care are currently unknown. We propose the Redefining Optimal PEth Cutoffs for Alcohol Screening (ROCS) to recruit 900 persons who drink alcohol using the electronic health records of a large urban health system, who had recent (past 3 months) alcohol screening. New technology allows for nearly continuous objective data on alcohol use that can be used as an excellent gold standard for determining PEth cutoffs. We will measure alcohol use over 28 days, using (1) a wrist-worn device called the BACtrack Skyn that measures alcohol excreted through the skin (transdermal alcohol concentration -TAC) every 20 seconds, and (2) brief daily surveys via a cell-phone app, to elicit drinks consumed in the prior 24 hours. We will create a composite gold standard measure of 28-day drinking combining the TAC and daily survey results to determine if 28-day drinking exceeds the NIAAA threshold for heavy drinking (≥8/≥15 drinks/week or ≥4/≥5 drinks/day for women/men). We will determine the optimal PEth cutoff for heavy drinking overall and by sex and BMI (under/normal weight vs. overweight/obese) and explore PEth cutoffs for other drinking thresholds (Aim 1),. Next, we will determine if other biologic factors independently affect PEth levels, such as age, race/ethnicity, body composition, liver fibrosis risk, and anemia (Aim 2). Lastly, we will estimate under-reporting of unhealthy alcohol use in primary care, by comparing PEth measured unhealthy drinking at ROCS baseline to self- reported unhealthy drinking that was reported during a recent (past 3 months) primary care visit (Aim 3). This research can be used by healthcare providers to improve recognition of unhealthy alcohol use, determine appropriate alcohol treatment and referral, and inform future use of PEth in healthcare.
