LOS ANGELES — Doctors are fueling the epidemic of prescription drug addiction and overdose and represent the single largest supplier of these drugs to chronic abusers, according to a government study published Monday.

The finding challenges the conventional wisdom that the epidemic is caused primarily by abusers getting their drugs without prescriptions, typically from friends and family.

Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, said in an interview that the study shows the need to focus more on doctors who are “problem prescribers.”

Frieden said the new study, along with the Times investigation and a second JAMA article on the widespread use of narcotic painkillers in Tennessee, all showed that physician prescribing was a key contributor to the crisis of addiction and overdose that has continued to mount since the CDC declared it an epidemic in 2011.

Prescription drugs contribute to more than 16,000 fatal overdoses annually and are the main reason drugs have surpassed traffic accidents as a cause of death in the U.S.

“At this point, virtually everyone recognizes that this is a serious problem that has been getting much worse,” Frieden said. “What we now are figuring out is what’s going to work to reverse it.”

CDC researchers analyzed data from the National Survey on Drug Use and Health, an annual snapshot of the use of illegal drugs, such as heroin and cocaine, as well as the “nonmedical use” of prescription drugs. The survey is widely used by researchers to gauge the scope and contours of the nation’s drug problem and by policymakers to determine how best to combat it.

Previous analyses of the survey had lumped all types of prescription drug misuse, from occasional to chronic, together. Those analyses identified friends and family members as the most common sources of misused prescription drugs.

The new analysis found that, while most survey respondents got prescription drugs from people they knew, chronic users got them most often, more than a quarter of the time, from a doctor.