Many of the thorniest issues in health care in recent years have had to do with chronic, long-term pain.

Regulators have debated how tightly to crack down on opiates that can lead to addictions.

Insurers have dithered over when to pay for acupuncture and alternative remedies.

And, most recently, lawmakers have debated whether intractable pain should be treated with medical marijuana.

Small wonder, then, that pain management was among the first topics analyzed by the Minnesota Department of Health with its new big-data tool, the All Payer Claims Database. The tool lets researchers crunch medical records of insured Minnesotans, minus identifying information, and compute health care trends.

In a report to the Legislature last week, state health economists found that the number of pain procedures increased 13 percent from 2010 to 2012.

About 60 percent involved women with chronic pain — acute procedures such as epidurals for childbirth are not included — and 44 percent involved patients 60 and older.

"It does reveal, perhaps, the graying of Minnesota and what might be driving some future health care costs in the state," said Diane Rydrych, a health department policy director.

The Legislature requested the report to identify what type of practitioners perform chronic pain procedures.

Most of the 660,000 pain procedures were spinal injections for back pain or tendon injections for joint pain. Most were performed by MDs who are pain specialists, though primary care doctors also performed nerve blocks to numb pain and tendon injections. Osteopathic doctors and nurse anesthetists combined to perform fewer than one in 10 of the procedures.

Other forms of chronic pain relief provided by chiropractors, podiatrists or other alternative health care providers were not studied.

"It does raise some interesting follow-up research ideas," Rydrych said. "What's the cost of chronic pain? What's the burden of chronic pain on the health care system?"

Now, state researchers have the big data at hand to answer such questions.