A 65-year-old couple retiring in 2008 will need around $225,000 to cover medical costs in retirement, according to a new study.

Fidelity Investments, Boston, which conducted the study, notes that its total retirement health care cost estimate increased by 4.7% over its 2007 estimate of $215,000.

Since Fidelity first calculated the cost in 2002, the figure has risen a total of 41%, or an annual average of 5.8%.

The estimate assumes individuals do not have employer-sponsored retiree health coverage. It includes expenses associated with Medicare Part B and D premiums (30%), Medicare cost-sharing provisions (39%) and prescription drug out-of-pocket costs (31%). It does not include such other health-related expenses as over-the-counter medications, most dental services and long term care.

Significant causes of the cost increase from 2007 to 2008 include higher costs for a doctor’s visit, more doctor visits per person, new health care technologies, prescription drugs and an increase in some chronic conditions such as diabetes, Fidelity says.

The company calculated the impact that a $225,000 health care liability would have on a retiree’s Social Security benefit. It found that a 65-year-old worker today who is earning $60,000 and who decides to retire this year could expect 50% of his or her pre-tax Social Security benefit would be used to pay for personal health care expenses in the next 17 to 19 years.

The estimate assumes a 3% Social Security annual cost-of-living adjustment and annual medical inflation of 6.6%.