The study published Monday examined

The study published Monday examined just how many new cases of drug-resistant HIV would result in Los Angeles County if test-and-treat policies were followed here. Lead study author Neeraj Sood, a clinical pharmacy professor at the USC Schaeffer Center for Health Policy, and colleagues used national and local HIV tracking data from 2000 to 2009 to create a mathematical model of the disease's spread.

Los Angeles is the county with the nation's largest incident population of HIV. Study authors determined that if the county adopted a test-and-treat policy now, in 10 years it would see a 34% reduction in new infections, a 19% reduction in deaths and a 39% reduction in AIDS cases. However, the county would also experience an increase in the number of cases of drug-therapy-resistant HIV -- an increase from 4.70% to 9.06%.

Study authors said that it was unclear how this increased resistance would affect the course of the HIV epidemic but that health officials should consider it when evaluating treatment policies. They also said that by just increasing testing and not changing treatment protocols, patients would see only half the benefits of a test-and-treat plan, but there would be no increase in drug resistance.

"With such uncertainty about the course of multi-drug resistance (MDR), it is unclear whether benefits from increasing test-and-treat outweigh costs of increasing MDR," the authors wrote. "If policymakers are risk-averse, a more cautious approach to HIV prevention might involve more focus on testing without changing treatment guidelines to cover early-stage HIV."