To do so, they used national registry data that included information on 6.3 million adults in Denmark. The participants, aged 46 to 56, were split into groups with either low, moderate or high baseline cardiovascular risk and were followed for 20 years from 1996 until 2016.
They found that, within 30 days of starting diclofenac, there was an increased rate of major adverse cardiovascular events, such as irregular heart beat or flutter, ischemic stroke, heart failure and heart attack, compared to those starting other traditional NSAIDs.
» RELATED: Common painkillers linked to increased heart risks, new study finds
In fact, the risk of having an adverse cardiovascular event was upped by 50 percent among those who took diclofenac, compared to those who had not.
Furthermore, they said there was also a relationship between diclofenac and an increased rate of cardiac death and upper gastrointestinal bleeding.
"Treatment of pain and inflammation with NSAIDs may be worthwhile for some patients to improve quality of life despite potential side effects," the team wrote in a statement. "Considering its cardiovascular and gastrointestinal risks, however, there is little justification to initiate diclofenac treatment before other traditional NSAIDs."
The scientists acknowledged the study was observational. However, they noted their sample size was larger than most previous analyses on similar topics.
A 2018 study of 57,000 people in Taiwan, published in the British Journal of Clinical Pharmacology, revealed that some prescription pain relievers, such as ibuprofen and naproxen, may be linked to irregular heartbeat.
Another study published in March 2017, which analyzed nearly 30,000 patients, concluded that the consumption of any kind of NSAIDs such as ibuprofen could boost the risk of heart attack by 31 percent.
» RELATED: More than 11 million Americans prescribed wrong dose of common drugs, scientists say