Americans and Canadians are seven times more likely to fill a prescription for opioid pain pills in the week after surgery than Swedes, says a study published Wednesday, one of the first to quantify international differences.

More than 75% of patients in the U.S. and Canada filled a prescription for opioids following four common surgeries, compared with 11% of Swedes, researchers report in JAMA Network Open. Americans also received the highest doses of opioids.

So, are Americans and Canadians wimpier than Swedes when it comes to pain, or is something else going on?

“There are a lot of tough people in lots of places,” demurred Mark Neuman, an associate professor of anesthesiology at the University of Pennsylvania Perelman School of Medicine and a co-author of the study.

He pointed to a host of other potential factors, from cultural differences to variations in marketing, regulation and long-standing, ingrained prescribing habits.

“It’s possible that in the U.S. people think about opioids as pain relief in a drastically different way than in other places,” he said.

Researchers examined four types of surgeries — minimally invasive types of appendectomy and gallbladder removal, as well as arthroscopic surgery to repair a torn meniscus in the knee and breast tumor removal. All the surgeries occurred from 2013 to March 2016, a time of growing concern about opioid dependence in the United States but before more recent guidelines suggesting that fewer pills are needed following many common surgeries.

Even so, “for the same exact surgery, the same exact tissue trauma, we have seven times more people in the U.S. getting opioids,” said Neuman.

On average, patients in the U.S. filled prescriptions for about 33 pills, each equivalent to 5 milligrams of oxycodone, he said, although the type of drug varied. Swedes who filled prescriptions had an average of 26 pills, while Canadians had 22.

Canadians and Swedes were also far more likely to get codeine or tramadol — painkillers that rely on a different mechanism in the body and are considered weaker types of opioids. Americans were far more likely to get hydrocodone or oxycodone, some of which were heavily marketed to physicians by drugmakers. States and cities are currently suing manufacturers, alleging they misrepresented the drugs’ risks and didn’t properly monitor suspiciously large sales, contributing to the opioid crisis.

The study does not comment on the marketing aspect but did note two factors that might account for some of the difference in the types of drugs prescribed. One is that, during the research period, low-dose codeine was available over the counter in Canada. Tramadol is still not classified as a controlled substance there, although it has been a controlled substance in Sweden since 2007 and in the U.S. since 2014.

“While prescribers may view these so-called weak opioids as safer alternatives, data suggests that both codeine and tramadol have the potential for misuse and life-threatening adverse effects,” the study says.

The U.S. and Canada were chosen because they have the highest per capita consumption rate of opioids in the world. Sweden was picked as a European counterpoint because researchers could obtain detailed prescription information from databases there.

While the study was large — following about 129,000 patients in the U.S. with job-based insurance, 84,600 in Canada’s Ontario province and 9,800 in Sweden — it did have limitations. For one, researchers could not track how many pills patients actually took of those prescribed, or the number of patients who didn’t fill prescriptions they were given. Secondly, they don’t have data on how well patients felt their pain was controlled following surgery.

“It’s possible that in Sweden everyone’s pain treatment is less than in the U.S., although I think that is unlikely,” said Neuman, noting that other studies have shown that patients in the U.S. often do not take all the pills they’ve been prescribed following surgeries.

In addition, for certain types of surgeries, patients do not report greater dissatisfaction when prescribed fewer pills after surgery. Researchers in Michigan, for example, recently reported on what happened after dozens of hospitals recommended new prescribing guidelines — drawn up after studying how many pills patients actually took — following certain surgeries. While recommendations were often for far fewer than 30 tablets, researchers found no increase in reported pain.

Like the group in Michigan, some academic medical centers and other experts have recently issued guidelines calling for fewer pills following many procedures. Those grew out of concern that patients with what is called acute pain — the kind following surgical procedures, for example — were given far too many pills.

An analysis of Medicare data by Kaiser Health News with researchers at Johns Hopkins Bloomberg School of Public Health, for example, found prescribing from 2011 to 2016 exceeded levels now recommended by organizations like Johns Hopkins. For example, Medicare patients took home 48 pills in the week following coronary artery bypass, 31 following laparoscopic gallbladder removal, 28 after a lumpectomy and 34 after minimally invasive hysterectomies.

According to postsurgical guidelines spearheaded by Johns Hopkins last year, those surgeries should require at most 30 pills for a bypass, and 10 pills for minimally invasive gallbladder removal, lumpectomy and minimally invasive hysterectomy.

Postsurgical opioid use can lead to long-term dependency in a small but significant percentage of patients, studies have shown, but unused pills can also be a danger. Those tablets can make their way to the street or fall into the hands of other family members.

Researcher Dr. Chad Brummett, who worked on the guidelines in Michigan, said he thinks prescribing amounts in the U.S. and Canada have likely dipped in recent years, given the increased attention.

Still, he cautioned that the amounts likely remain too high in both countries and that the new study illustrates the wide disparity between North America and at least one European country.

“We know that marketing in the U.S. has affected prescribing in all domains, including surgery,” said Brummett. “This study and others show that [surgeons] in the U.S. and Canada can drastically reduce prescribing standards without adversely affecting patient care.”