The number of people covered by the health insurer Blue Cross Blue Shield who were diagnosed with an opioid addiction rose almost 500 percent from 2010 to 2016, CNN reports.

The findings, from a study by the insurer, found few patients receive any treatment for their addiction. During the study period, there was only a 65 percent increase in the number of patients who received medication-assisted treatment for their addiction.

The study found states that have experienced the greatest growth in the use of medication-assisted treatments are not necessarily the areas most impacted by opioid use disorders. High rates of treatment relative to opioid use disorder occur in New England and lower rates occur in the South and parts of the Midwest.

Among those 45 and older, women have a higher rate of opioid use disorder than do men, according to the study. Among people younger than 45, men have higher rates of opioid use disorder than women.