Uninsured adults ages 59 through 64 who suffer from hypertension, diabetes, heart disease or stroke had health costs that were 51 percent higher than their insured counterparts once they entered Medicare, according to a recent Commonwealth Fund report.

The study, conducted by researchers at Harvard Medical School and published in the July 12 issue of the New England Journal of Medicine, found that those who were uninsured reported 13 percent more doctor visits and 20 percent more hospitalizations than those who had health insurance before becoming eligible for Medicare. Moreover, those higher costs continued through age 72 for the individuals who did not have health insurance before entering the federal health care program for the elderly and disabled.

“This study highlights the importance of health insurance coverage for all Americans to improve the efficiency of our health care system, as well as the quality of our health care and health outcomes,” Commonwealth Fund President Karen Davis said in a statement.

In a Commonwealth Fund news release, the study authors noted that poor control of high blood pressure and glucose and cholesterol levels can cause life-threatening complications such as heart attacks, strokes and kidney failure, increasing the need for costly medical care, hospitalizations and medications. The authors also noted that the costs of expanding health insurance for uninsured adults before age 65 may be partially offset by subsequent reductions in health care services after they reach age 65.

The study is based on a nationally representative sample of adults from the Heart and Retirement study, which is federally financed. Researchers followed 5,158 adults from 1992 through 2004, before and after they became eligible for Medicare, comparing the use of health care services for those who were insured to those who did not have health care insurance before entering Medicare.

Separately, new data from the Agency for Healthcare Research and Quality (AHRQ) found that a lack of health insurance also prevents many American women from not having a routine screening test for cervical cancer. According to the agency, one-fourth of uninsured U.S. women between the ages of 18-64 reported not having a Pap smear within the last three years when surveyed in 2005. That rate was double the 11 percent rate for women with private insurance and more than the 15 percent rate for women covered by Medicaid or any other public insurance.