People with HIV who have a low-level detectable viral load—meaning between 50 and 999—have a higher risk of death and serious non-AIDS health outcomes than those with an undetectable viral load (below 50).

Researchers studied data from some 7,000 Swedish people living with HIV who were followed for a median of nearly six years.

After adjusting the data to account for various differences between the cohort members, the study authors found that, compared with having an undetectable viral load, having a viral load between 50 and 999 was associated with about a twofold increased risk of death.

What’s more, having a viral load between 200 and 999 was associated with a doubled risk of AIDS and serious non-AIDS adverse health events. These events included cardiovascular disease, deep vein thrombosis, high blood pressure, chronic kidney disease, advanced liver disease and non-AIDS-defining cancers.

“Importantly, another study is needed to confirm or refute a causal relationship between low-level [detectable viral load] and adverse [health] outcomes. And our results need confirmation in other cohorts,” says the study’s lead author, Olof Elvstam, a research student at Lund University in Sweden.