The US Medicare prescription drug benefit has boosted medicines use among seniors, improved their adherence to essential drug treatment and reduced their out-of-pocket drug costs, according to a new study.

For older people who had only limited prescription drug coverage before the Medicare health programme's prescription drug benefit - known as Part D - was introduced in January 2006, the launch has led to significant reductions in non-drug medical spending, such as for in-patient and skilled nursing faulty care, add researchers J Michael McWilliams of Harvard Medical School and Brigham and Women's Hospital in Boston et al, reporting their findings in the July 27 issue of the Journal of the American Medical Association (JAMA).

The study estimates that savings to Medicare resulting from Part D have averaged around $12,000 a year for each older person with previously inadequate prescription drug coverage, or around $12 billion a year in total.

Because of the prescription drug benefit, seniors can afford medications which lower their cholesterol and blood pressure and control their diabetes without the need for hospital treatment, and they can also now receive drug therapy more cheaply at a doctor's office rather than in hospital, the results show.

"Spending on one type of service can reduce spending on another type of service. By expanding Medicare to include drug benefits, clearly we're spending more, but we're getting a lot of value out of that spending," the Associated Press reports Dr McWilliams as commenting.

The authors say that these new findings echo earlier study results which have suggested that wider use of, and adherence to, medication achieved through expanded drug coverage for seniors is linked to lower spending on non-drug medical care.

"The economic and clinical benefits suggested by these reductions may be enhanced by further expansions in prescription drug coverage for seniors, improvements in benefit designs for drug-sensitive conditions and policies that integrate Medicare payment and deliver systems across drug and non-drug services," they add.

Meantime, the IMS Institute for Healthcare Informatics has reported that the average costs of medicines used frequently by Medicare Part D beneficiaries have declined "significantly" since the programme was launched.

Specifically, average daily costs for medicines in the top 10 therapeutic classes in Part D fell by more than a third between January 2006 and December 2010, from $1.50 to $1.00, according to the IMS Institute. The report also forecasts that these costs will continue to decline, to $0.65 by the end of 2015, thus constituting a total decrease of 57% since 2006.

The Pharmaceutical Research and Manufacturers of America (PhRMA), which commissioned the report, said these findings provided "further evidence that Part D is a successful programme that provides unprecedented access to life-saving medicines for seniors."

The industry group also pointed out that both seniors and taxpayers are paying less than anticipated for the drug benefit, with the Congressional Budget Office (CBO) reporting recently that spending on Part D was actually 41% lower than its initial 10-year estimate.