Heavy drinkers more often end up in the hospital with pneumonia than those who go easy on the alcohol, suggests a new study from Denmark.

But it was only the biggest imbibers - men who said they had more than 50 drinks a week - who were at higher risk of catching the infection.

The study isn’t the first to draw a line between alcohol and pneumonia. Yet researchers can’t be sure that drinking by itself leads to pneumonia - it could be that alcohol-linked chronic diseases like liver and heart problems may be at play, for example.

In the current report, Dr. Reimar Wernich Thomsen, of Aarhus University Hospital, and his colleagues used data from a large Danish health study, including more than 45,000 people age 50 to 64, who had never had pneumonia.

All participants filled out surveys at the beginning of the study, which included questions on how often they drank beer, wine, and hard liquor. Women reported having an average of six drinks each week, while men said they downed 12 drinks per week.

Over the next 12 years, about four percent of the participants wound up in the hospital with pneumonia.

Regardless of how much they said they drank - from zero to more than 35 drinks each week - women had a similar risk of pneumonia, the researchers report in the European Respiratory Journal.

However, men who drank more than 50 drinks each week were about 80 percent more likely to go to the hospital for pneumonia than those who had between one and six drinks each week, after taking into account factors like smoking and weight.

About one in thirty men drank enough to land himself in that category.

When Thomsen and colleagues also accounted for other chronic diseases the men had developed, the link between alcohol and pneumonia remained, but was weaker.

“The general idea is that alcohol impairs the immune system - every single part of the immune system,” said Dr. Andriy Samokhvalov, of Toronto’s Center for Addiction and Mental Health, who was not involved in the new study.

If excessive drinking really does lead to pneumonia, exactly how much a person would need to drink to be at increased risk remains uncertain. And it doesn’t help that the study relied on people’s own reports of their drinking, which could weaken the results.

According to Samokhvalov, “we think there must be a threshold around four drinks per day.”

Both men and women had a higher pneumonia risk if they did their drinking infrequently in high doses, rather than spaced out over the week.

The researchers agreed it makes sense that people who binge drink and black out on the sidewalk would be hampering their immune system.

Dr. Marjolein de Wit, who studies alcohol and critical illness at Virginia Commonwealth University in Richmond, said that frequent drinkers also have a higher risk of picking up an infection like pneumonia in the hospital when they’re admitted for other reasons. And when they do get infected, their risk of dying is higher.

SOURCE: European Respiratory Journal, online June 9, 2011