SALT LAKE CITY — To a medical researcher, finding out that a longtime hunch is correct can be as good as getting a present on Christmas Day.
Dr. Kurt Hegmann, director of the Rocky Mountain Center for Occupational and Environmental Health at the University of Utah, has been working on one hunch for more than 20 years.
Hegmann started noticing in the 1990s that patients with musculoskeletal disorders like tendonitis and carpal tunnel often also had issues like high blood pressure, diabetes or tobacco use.
"It got me to wonder if there wasn’t a cardiovascular disease mechanism for these different disorders," said Hegmann.
Now, he has his answer — or at least a big hint.
Results from a study led by Hegmann and colleagues to be published in an upcoming issue of the Journal of Occupational and Environmental Medicine show that people who have risk factors for heart disease are several times more likely to have shoulder and rotator cuff issues.
Heart disease risk factors seem to be more correlated with shoulder problems than repeated physical strain, which many people have assumed is the biggest culprit.
"Even when you expect to find something and you find it, you're still surprised," said Hegmann. "... It's the joy of, 'Oh my gosh, a theory is panning out.'"
The study by Hegmann and colleagues is unique in its intensity, scope and length.
Researchers at the University of Utah and University of Wisconsin-Milwaukee began recruiting participants in 2002. They enrolled more than 1,200 workers in over a dozen types of occupations and surveyed them about their health issues.
An ergonomic team also videotaped them at their jobs, measuring the weights of the objects they lifted or moved to determine the physical stress.
Then they followed them for nine years.
Hegmann and colleagues were looking at many types of musculoskeletal disorders, including carpal tunnel and tennis elbow.
But the findings about shoulder injuries stood out.
The data shows a strong association between cardiovascular disease risk factors — like hypertension, tobacco use and diabetes — with shoulder joint pain and rotator cuff tendinopathy.
The more risk factors a patient had, the more likely he or she was to have shoulder issues, according to the study.
When adjusted for factors like gender, body mass index, job satisfaction and family stress, the 36 people with the most severe risk factors were 4.6 times more likely to have shoulder joint pain and 6 times more likely to have rotator cuff tendinopathy.
People with midlevel cardiac disease risk factors were about 1.5 to 3 times more likely to have either shoulder condition.
“When you see that kind of pattern, the probability of there being a significant cause is much higher,” Hegmann said. "These are not minor risks.”
The study only proves correlation, not cause-and-effect, but Hegmann said patients should be aware of the link — particularly young people who are at risk of heart disease and have shoulder pain.
"I would be at my doctor saying, 'I'm probably one of those people that needs to go take those cholesterol medications,'" Hegmann said.
The study also found that a more physically demanding job was not correlated with shoulder injury.
Between airbag manufacturers, cabinet makers and meat processors, there was no evidence that a more physically strenuous job translated to more shoulder problems.
Researchers are not sure why heart disease might be associated with shoulder joint pain and rotator cuff injury, but the theory is that decreased blood supply to the shoulder causes the tendons to weaken.
Hegmann estimates he and colleagues will be analyzing the data for another five years, mining it for more discoveries.
That will be time-consuming work, but it's worth it, Hegmann said.
"You look at the data and you say, 'Oh, we have to analyze this,’” he said. “This is not optional."