On 2016 Aug 21, David Keller commented:

Goulden's results confirm the J-shaped relationship of all-cause mortality with alcohol intake

In my recent letter about Goulden's study, I pointed out that his data actually confirm the benefit of mild alcohol ingestion for reducing all-cause mortality. I supply the text of my letter below, exactly as it was published, for convenient reference. Goulden should have titled his paper, "Yet more data confirming that a "J-shaped" relationship exists between the amount of alcohol consumed daily and the risk of all-cause mortality." My detailed rebuttal of Goulden's reply is at the following URL:

http://www.ncbi.nlm.nih.gov/pubmed/27453387#cm27453387_26107

Here is the text of my letter:

"Goulden's conclusion that moderate alcohol consumption is not associated with reduced all-cause mortality in older adults conflicts with the findings of other studies, which he attributes mainly to residual confounding and bias. However, Goulden's own Table 2 indicates that regular drinkers who consume less than 7 drinks per week (whom I shall call “light drinkers”) actually do exhibit the lowest average mortality hazard ratio (HR), compared with nondrinkers or heavy drinkers (>21 drinks per week), even when fully adjusted by Goulden, for all 11 categories of subjects, based on age, sex, health, socioeconomic, and functional status.

"Likewise, for those who consume 7 to 14 drinks per week (“moderate drinkers”), Table 2 reveals that their average mortality HR is less than that of nondrinkers or heavy drinkers, with only 1 outlying category (of 11 categories). This outlier data point is for subjects aged less than 60 years, which may be explained by the fact that the ratio of noncardiovascular mortality (particularly automobile accidents) to cardiovascular mortality is highest in this youngest age category. Thus, the trends exhibited by Goulden's average data are consistent with the previously reported J-shaped beneficial relationship between light-to-moderate ethanol ingestion and mortality, with the single exception explained above.

"Goulden defines a new category, “occasional drinkers” as those who “report drinking at least once, but never more than ‘less than once per week,’” and assigns them the mortality HR of 1.00. Because occasional drinkers consume alcohol in amounts greater than nondrinkers, but less than light drinkers, their mortality should be between that of nondrinkers and that of light drinkers.

"However, for 5 of the 11 categories of subjects analyzed, the mortality HR for occasional drinkers is less than or equal to that of light drinkers. This may be due to subjects who miscategorize their light alcohol intake as occasional. The effects of this error are magnified because of the small amounts of alcohol involved, and thereby obscure the J-shaped curve relating alcohol intake and benefit.

"The only way to determine with certainty what effect ethanol ingestion has on cardiovascular and total mortality is to conduct a randomized, controlled trial, which is long overdue."

Reference

1: Goulden, R. Moderate alcohol consumption is not associated with reduced all-cause mortality. Am J Med. 2016; 129: 180–186.e4

On 2016 Aug 21, David Keller commented:

Goulden's results confirm the J-shaped relationship of all-cause mortality with alcohol intake

In my recent letter about Goulden's study, I pointed out that his data actually confirm the benefit of mild alcohol ingestion for reducing all-cause mortality. I supply the text of my letter below, exactly as it was published, for convenient reference. Goulden should have titled his paper, "Yet more data confirming that a "J-shaped" relationship exists between the amount of alcohol consumed daily and the risk of all-cause mortality." My detailed rebuttal of Goulden's reply is at the following URL:

http://www.ncbi.nlm.nih.gov/pubmed/27453387#cm27453387_26107

Here is the text of my letter:

"Goulden's conclusion that moderate alcohol consumption is not associated with reduced all-cause mortality in older adults conflicts with the findings of other studies, which he attributes mainly to residual confounding and bias. However, Goulden's own Table 2 indicates that regular drinkers who consume less than 7 drinks per week (whom I shall call “light drinkers”) actually do exhibit the lowest average mortality hazard ratio (HR), compared with nondrinkers or heavy drinkers (>21 drinks per week), even when fully adjusted by Goulden, for all 11 categories of subjects, based on age, sex, health, socioeconomic, and functional status.

"Likewise, for those who consume 7 to 14 drinks per week (“moderate drinkers”), Table 2 reveals that their average mortality HR is less than that of nondrinkers or heavy drinkers, with only 1 outlying category (of 11 categories). This outlier data point is for subjects aged less than 60 years, which may be explained by the fact that the ratio of noncardiovascular mortality (particularly automobile accidents) to cardiovascular mortality is highest in this youngest age category. Thus, the trends exhibited by Goulden's average data are consistent with the previously reported J-shaped beneficial relationship between light-to-moderate ethanol ingestion and mortality, with the single exception explained above.

"Goulden defines a new category, “occasional drinkers” as those who “report drinking at least once, but never more than ‘less than once per week,’” and assigns them the mortality HR of 1.00. Because occasional drinkers consume alcohol in amounts greater than nondrinkers, but less than light drinkers, their mortality should be between that of nondrinkers and that of light drinkers.

"However, for 5 of the 11 categories of subjects analyzed, the mortality HR for occasional drinkers is less than or equal to that of light drinkers. This may be due to subjects who miscategorize their light alcohol intake as occasional. The effects of this error are magnified because of the small amounts of alcohol involved, and thereby obscure the J-shaped curve relating alcohol intake and benefit.

"The only way to determine with certainty what effect ethanol ingestion has on cardiovascular and total mortality is to conduct a randomized, controlled trial, which is long overdue."

Reference

1: Goulden, R. Moderate alcohol consumption is not associated with reduced all-cause mortality. Am J Med. 2016; 129: 180–186.e4