Medicare may be shortchanging geriatric physicians, a new, limited study finds.

For every 30 minutes that a sample of geriatricians spent seeing patients, they also spent an average of more than six additional minutes providing care that was not reimbursed by Medicare. This care could include time spent talking to families, ordering medicine or consulting with other physicians. This could equate to eight uncompensated hours every week, researchers found.

The study of 16 geriatric physicians took place at the Mount Sinai School of Medicine in New York. It appeared in last month’s Annals of Internal Medicine. The Centers for Medicare & Medicaid Services reportedly said the findings were based on a false assumption about Medicare payment for services.