Alcohol intake increases blood pressure

A recent systematic review and meta-analysis of cohort studies found that any alcohol consumption was associated with an increased risk of hypertension in men, though only higher consumption was associated with an increased risk in women (see htn alcohol JAHA2018 in dropbox, or  DOI: 10.1161/JAHA.117.008202​).

Details
-- 20 reports from 18 international studies with 361,254 people (125,907 men and 235,347 women), and 90,160 incident cases of hypertension (32,426 men and 57,734 women) were included.
-- Mean age at baseline in men range from 25 to 57 years, weighted mean of 47 and mean follow-up duration of 5.3 years; and women mean age range from 25 to 60 with a weighted mean of 47 and mean follow-up of 7.3 years
-- most studies were adjusted for potential confounders
-- Hypertension was defined as a systolic blood pressure >140 mmHg and a diastolic >90 mmHg.
-- one alcohol drink was defined as 12 g of ethanol

Results:
-- in alcohol drinkers, the incidence of hypertension (as compared to alcohol abstainers) was:
    -- for men:
        -- 1 to 2 drinks per day: 19% increased risk, RR 1.19 (1.07-1.31)
        -- 3 to 4 drinks per day: 51% increased risk, RR 1.51 (1.30-1.76)
        -- 5 or more drinks per day: 74 % increased risk, RR 1.74 (1.35-2.24)
    -- for women:
        -- 1 to 2 drinks per day: no significant difference
        -- 3 or more drinks per day: 46% increased risk, RR 1.46 (1.22 1.66)
-- in former drinkers, there was no difference in hypertension as compared to lifetime abstainers

Commentary:
 -- hypertension is the 3^rd most important risk factor for the global burden of disease, affecting more than 1 billion people worldwide with a global prevalence of 20% that is increasing over time, and is responsible for 10.7 million deaths and 211 .8 million disability adjusted life-years
-- prior studies have shown that high levels of alcohol consumption were associated with hypertension, some suggesting there was a J curve where lower doses of alcohol consumption were actually protective/better than not drinking at all. This study found that no level of alcohol intake was associated with lower blood pressure​
-- the new AHA guidelines for detection evaluation and management of high blood pressure (see http://gmodestmedblogs.blogspot.com/2017/11/new-aha-hypertension-guidelines.html), notes that alcohol may account for 10% of the hypertensive population in the US, and recommends limiting daily alcohol intake to 2 drinks for men and one drink for women. [perhaps this should be reconsidered....]
--A meta-analysis of 36 trials with 2865 people found that in those who drank more than 2 drinks per day, a reduction in alcohol consumption was associated with a systolic blood pressure reduction of 5.5 mmHg and diastolic of 4.0 mmHg, and this was strongest in those who drank 6 or more drinks per day if they reduced their intake by 50%. However, only 401 women were part of this analysis.​ (see alcohol reduction dec BP lancetpubhealth2017 in dropbox, or Roerecke M. Lancet Public Health. 2017;2:e108–e120. nm)
-- limitations of this study: as a meta-analysis, there are the usual concerns: these were different studies in different populations with different inclusion and exclusion criteria, all jumbled together. There were sensitivity analyses done to see the effect of the intrinsic study differences by ethnicity/race, different potential confounders, differences in ages, and different sizes of studies; none of these analyses showed major differences (though in some cases the number of events was too low to be statistically useful). Most of these studies involved self-reported alcohol consumption, which may not be fully reliable. In addition this meta-analysis was based on observational cohort studies, so it is not possible to determine causality.​
-- also, this study only looked at total reported alcohol consumption, and did not look at patterns of drinking, including binge drinking. So, for example, for people averaging 2 drinks per day, this type of study would include those drinking 2 drinks every day in the same category as those drinking 7 drinks on 2 days per week. And the effects on hypertension as well as other alcohol-related morbidities may well be different.
-- relevant prior blogs:
    --For an analysis suggesting that even low levels of drinking may be harmful for cardiovascular health, see http://gmodestmedblogs.blogspot.com/2015/02/moderate-alcohol-and-cardioprotection.html  . this blog notes that the "protective" effect of moderate drinking may be that "non-drinkers" included people who had been excessive drinkers, who as a group may have increased mortality for a variety of reasons (depression, long-term effects of excessive drinking on many parts of the body). A long-term English study was reported that excluded former drinkers and found there was minimal "protection" overall at any level of alcohol consumption (see alcohol and mortality bmj 2015 in dropbox or https://www.bmj.com/content/350/bmj.h384 ). This blog also references Mandelian randomization studies, which methodologically decrease the likelihood of confounding and sort of act like RCTS, and did not find that alcohol decreased the CAD biomarkers (increased HDL, reduced CRP, reduced fibrinogen), and did not find the previously touted "health-promoting" effects on cognitive function or blood pressure (see https://onlinelibrary.wiley.com/doi/epdf/10.1111/add.12828 ).  
    ​--http://gmodestmedblogs.blogspot.com/2016/04/bmi-height-and-socioeconomic-status.html references a study (BMJ 2014; 349:g4164 4 doi: 10.1136/bmj.g4164​) of Manelian randomization finding that lower CAD rates were associated with genetic variants of alcohol dehydrogenase and not with alcohol consumption itself
-- though the relationship between alcohol consumption and hypertension in women was a bit unexpected to me, especially since the definition of moderate drinkers involves half the alcohol consumption by women than men, this has been a somewhat consistent finding, as noted in upcoming blog on binge drinkers
-- BUT, it is important to put the above result on hypertension in a broader context: alcohol is also a pretty potent carcinogen (see https://www.cancer.gov/about-cancer/causes-prevention/risk/alcohol/alcohol-fact-sheet ) -- for liver, head and neck, esophageal, and colorectal cancer, and also for breast cancer in women, where even "moderate" alcohol intake is associated with a 30-50% increased risk of breast cancer (see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3832299/ )

So, this article reinforces that even low levels of alcohol consumption may have serious consequences in terms of hypertension. And it reinforces that we clinicians should be regularly and repeatedly inquiring about alcohol consumption, in hypertensive and normotensive patients, and in men and in women, noting that even small amounts of alcohol may increase blood pressure (with its various clinical sequelae) as well as other bad outcomes (eg, cancer). And we should be helping patients work on plans to stop or at least decrease alcohol consumption in drinkers.

geoff​

If you would like to be on the regular email list for upcoming blogs, please contact me at gmodest@uphams.org

to get access to blogs since 8/15/17:

1. go to http://gmodestmedblogs.blogspot.com/ to see them in reverse chronological order

2. click on 3 parallel lines top left, if you want to see blogs by category, then click on "labels" and choose a category​

3. or you can just type in a name in the search box and get all the blogs with that name in them

to access older blogs from the BMJ website, from October 2013 until 8/15/17: go to http://blogs.bmj.com/bmjebmspotlight/category/archive/ 

please feel free to circulate this to others. also, if you send me their emails, i can add them to the list