A new study finds one in three people treated with prescription opioid painkillers show symptoms of dependence and opioid use disorder, The Guardian reports.

The researchers reviewed 148 studies enrolling more than 4.3 million adult chronic pain patients treated with prescription opioid painkillers. In the journal Addiction, the researchers report that nearly 10% of patients experience opioid dependence or opioid use disorder, and nearly one-third show symptoms of dependence and opioid use disorder.

“Clinicians and policy makers need a more accurate estimate of the prevalence of problematic opioid use in pain patients so that they can gauge the true extent of the problem, change prescribing guidance if necessary, and develop and implement effective interventions to manage the problem,” lead author Kyla Thomas, Professor of Public Health Medicine at the University of Bristol said in a journal news release. “Knowing the size of the problem is a necessary step to managing it.”