The majority of elderly people in assisted-living or residential care facilities do not receive the medications they need for heart attacks, osteoporosis, heart failure or strokes, according to study results released Monday.

Researchers at the University of North Carolina in Chapel Hill reviewed the medical records of 2,014 assisted living or residential care facility residents, all 65 years of age or older. They found that for people with a history of heart attack, more than 60% were not taking aspirin and 75% did not receive beta-blockers, which are used to prevent repeat attacks.

Among the study’s other findings, more than 60% of the residents with osteoporosis were not taking calcium supplements, with over half not receiving treatment at all. More than 60% of subjects with congestive heart failure and more than one-third of stroke patients did not receive proper medication, according to a report on the study in the Archives of Internal Medicine.

Doctors are sometimes hesitant to prescribe elderly residents medication because of lack of information about drug safety in older patients, said expert Dr. Jerry H. Gurwitz. More studies involving the treatment of older patients with new medications could alleviate the alarming under treatment of elderly residents, Gurwitz said.