When Dr. Eriko Onishi came to the United States from her home country of Japan, she ended up with culture shock on the number of opioids being prescribed.
Onishi got her medical training in Japan and spent about a year there practicing medicine before coming to the United States. She was used to that country's strict attitudes around opioid painkillers like Vicodin or Oxycontin, which are generally only prescribed in cases where a patient is in severe pain, as with cancer. In Japan, opioids for acute pain aren't typically covered by insurance.
When Onishi started practicing family medicine in Oregon, she was shocked to see patients getting opioids for injuries as minor as toothaches and sprained ankles. And she started seeing a disturbing trend among her own patients: people constantly requesting opioids for pain.
More from Vox:
Trump administration: sanctuary cities don't deserve crime-fighting help
If you want to know how the alt-right upended American politics, read Kill All Normies
Peter Thiel's investment in Donald Trump doesn't seem to be paying off
"It's the patient begging you to 'give me the opioid,'" Onishi said.
Onishi started wondering about a question at the heart of the American opioid crisis: Why is the United States such an outlier when it comes to dependence on powerful, addictive painkillers? After all, people in other countries also break bones, have surgery, and suffer from back pain and arthritis.
But the United States stands out for the sheer amount of opioids like Vicodin and Oxycontin it consumes, fueling a deadly drug epidemic. With just 4 percent of the world's population, the US accounts for about 27 percent of the world's drug overdose deaths.
The federal government estimated 8.5 million Americans, about 3 percent of the population, misused opioid painkillers in 2015, and 2.5 million were addicted to either painkillers or heroin. More than 33,000 people died that year from overdoses.
The European Union's entire population exceeds that of the United States, but it has a fraction of the opioid use. Out of the approximately 507 million people living in the EU in 2014, 1.3 million — or 0.4 percent — were considered high-risk opioid users. That same year, officials recorded 6,800 drug overdose deaths in the EU; opioids were to blame in about 80 percent of those deaths.
There are no corresponding statistics for Japan, but if you compare the United States to the entire continent of Asia, you see a similar picture. In 2015, 52,400 Americans died from drug overdoses, while about 62,000 people in Asia did.
Part of the difference is cultural: American and Japanese doctors view pain differently. Part of it is regulatory: In Europe, opioids are much more tightly regulated. The American opioid epidemic is what you get when you pair a culture that values treating pain at all costs with a regulatory environment that makes dangerous and addictive drugs relatively easy to obtain.