More than 43 million US senior citizens have started choosing a new prescription drug plan under the biggest change to the country's Medicare scheme since 1965. But many are finding the choice of different schemes bewildering.

Senior citizens can join without penalty as late as 15 May 2006, but for coverage to begin by 1 January 2006, they must select by the end of this year. The drug benefit is going to cost an estimated $724bn (£421bn; €615bn) over 10 years, as senior citizens have on average six prescriptions each. Some say it is President Bush's biggest domestic achievement. Up to now, …