PEth and AUDIT flagged different drinkers; neither is enough alone

Design

Retrospective cohort study using linked primary care and registry data

Population

3,679 patients with PEth and AUDIT; 8,934 with PEth and weekly drinks, Sweden

Primary outcome

Concordance between PEth and self-reported alcohol measures

Effect

Hazardous use: AUDIT 26.5%, PEth 14.6–18.3%, weekly drinks 8.5%; moderate, non-linear correlation

Phosphatidylethanol (PEth) is a blood marker of alcohol intake over the preceding two to four weeks, and it is increasingly offered as an objective alternative to asking. A retrospective study in the Annals of Family Medicine (21 September) used Swedish primary care records to compare PEth with the AUDIT questionnaire in 3,679 patients and with self-reported weekly drinks in 8,934.

How many patients looked hazardous depended on how you asked. AUDIT of 8 or more flagged 26.5%; PEth above 210 ng/mL flagged about 15–18%; ten or more reported drinks a week flagged only 8.5%. Each method picked up patients the others missed. PEth correlated only moderately with self-report, and the relationship shifted by patient: at the same PEth level, men and those with more education or income reported drinking more, and younger patients scored higher on AUDIT.

The practical message is that PEth adds information but does not replace the conversation. A high PEth in someone who reports little drinking is an opening for a non-judgemental discussion, not a verdict; a normal PEth does not cancel a high AUDIT. Where PEth is not available — as in much of Indian primary care — a structured questionnaire such as AUDIT-C remains the practical first step. This is observational data from one Swedish region, and the tests were not ordered at random.

• Use a structured questionnaire such as AUDIT-C as the routine first step for alcohol screening.
• Where PEth is available, interpret it alongside self-report, not instead of it.
• A raised PEth with low reported drinking is a prompt for a non-judgemental conversation.
• Reported weekly drinks alone identified the fewest at-risk patients; ask more than one question.

Why it matters

It challenges the idea that an objective blood test can replace asking patients about alcohol.

Don't overread it

PEth was tested when clinicians chose to order it, so these patients may not represent a general screening population.

The statistics, in plain English

The prevalence figures come from different thresholds and slightly different groups, so they show how much the method changes the answer, not which method is 'right'. A moderate correlation means PEth and self-report move together on average but often disagree for an individual.

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