People with HIV who smoke were 91% less likely to achieve an undetectable viral load than those who didn’t smoke, according to data published in the journal Drug and Alcohol Dependence.

Meanwhile, people who were heavy drinkers but didn’t smoke saw no such significant associations, an observation that differs from previous research findings.

Derek Satre, PhD, of the University of California San Francisco, and colleagues reviewed the medical records of 8,958 people living with HIV who received treatment at Kaiser Permanente Northern California and tracked data on how often the participants reported smoking and drinking. Then they followed how likely the participants were to be linked to HIV care, to remain engaged in care and to experience viral suppression.

Just 9% of Kaiser members with HIV were women, and there were no measures of transgender experience. About half of the participants were white (54%), 18% were Latino and 15% were Black. The median age was 48.

The researchers defined unhealthy alcohol use as men age 65 or younger having four or five or more drinks in a single day, or eight or more or 15 or more drinks a week in the past 90 days. The number of drinks was lower for women. For smoking, they only looked at whether the Kaiser member reported current cigarette smoking.

They found that nearly three out of four members didn’t smoke and didn’t report unhealthy drinking. But one in 10 Kaiser members did report unhealthy alcohol use, and nearly twice as many,19%, were current smokers. Most of those, 16%, only smoked and didn’t report unhealthy levels of drinking. Three percent of participants both smoked and met the criteria for unhealthy drinking.

Overall, 84% of members were engaged in care, defined as at least two visits or lab results in a 12-month period that were at least 60 days apart. The researchers defined undetectable viral load as fewer than 75 copies; 92% of the participants achieved such viral suppression during the analysis period.

When the researchers looked at smoking and drinking in the context of the HIV care continuum, they found that Kaiser was least likely to link to care people who were both smokers and heavy drinkers, with 2.8 times fewer of them linked to care. But people in that group who were linked to care were equally likely to stay in care and achieve an undetectable viral load.

Likewise, Kaiser did a good job of linking and engaging heavy drinkers in care, and those individuals also were as likely to achieve an undetectable viral load as their non–problem-drinking peers.

But the system did less well in serving smokers, who were 60% less likely to be linked to HIV care in the first place, 30% less likely to stay engaged in care and a full 91% less likely to achieve an undetectable viral load. This was after adjusting for race, socioeconomic status and sex.

Previous studies have suggested that people with HIV were less likely to be offered nicotine replacement therapy than their HIV-negative peers, but previous research into nicotine-replacement prescribing at Kaiser Permanente Northern California found that people with HIV were more likely to be prescribed nicotine replacement.

“Our findings on the relationship of smoking to poor viral control provide added urgency to address smoking among [people living with HIV],” Satre and colleagues wrote. “These findings contribute to the literature on the relationship of smoking to health among people with HIV.”

Click here to read the study abstract.

Click here to read more about smoking and HIV.