Democratic presidential hopeful Senator Barack Obama has lent his support to concerns over seriously-ill patients, after it emerged this week that US insurers are increasingly charging members being treated with the most expensive drugs a percentage of the costs of these medications, instead of the standard set copayment.

These so-called Tier 4 payments were unknown five years ago but started to appear after the Medicare prescription drug benefit was introduced in 2006. Under Tier 4, insurers require members being treated for diseases including some cancers, hepatitis C, multiple sclerosis and rheumatoid arthritis to pay as an average of 20%- 33% of the drug’s total costs, or thousands of dollars a month. 86% of Medicare plans and 10% of private plans now include a Tier 4 payment system - some even have a Tier 5 scheme for the most expensive drugs.

The practice was first exposed earlier this week by the New York Times, which puts the blame squarely with the high prices which it says drugmakers, and particularly biotechnology companies, charge for their products. Employers, including the federal government, also bear responsibility, by seeking to reduce their costs by shifting a greater share of prescription drug spending to patients, it adds.

Insurers’ traditional tiered formularies, in which patient copayments usually average $10-$30 and increase along with the drugs’ costs, are “a sensible approach for encouraging consumers to use the cheapest drug suitable for their condition,” but for Tier 4 drugs the copayments can be “huge” and suitable, cheaper alternatives for the medications may not exist, it goes on.

The insurers say that Tier 4 payments for the most expensive drugs allow premiums for the rest of their members to be kept down. However, says the Times: “it doesn’t take a health policy expert to recognize that something has gone terribly wrong when patients have to pay thousands of dollars a month for drugs that they need to maintain their health - and possibly save their lives.”

Sen Obama described the practice as “unconscionable” and has called for a response from Linda Springer, director of the Office of Personnel Management (OPM), which regulates the Federal Employees Health Benefit Program (FEHBP), as some of the plans offered by the Program to its more than 8 million members have been named as operating Tier 4 schemes.

The situation is “troubling for several reasons,” says Sen Obama, in a letter to Ms Springer. “For many of these drugs, there are no affordable drug alternatives, including generic drugs. These higher copayment schemes also do not take into consideration the value of a drug, with respect to long-term financial implications and health and quality of life outcomes for patients. Further, this practice runs contrary to the underlying premise of health insurance, which is to spread health care risk, unfairly penalizing patients who become ill,” he writes.

Sen Obama asks the OPM director to provide him with information, by April 30, on: the prevalence of the practice in certain plans; how many federal employees are charged in each tier of copayment; whether enrollees can choose between plans with various copayment options; and what further federal regulation is needed to ensure federal employees have access to affordable life-saving or disease modifying drugs.

The New York Times also calls on Congress to find out how many patients are now affected and how they can best be protected from medical and financial disaster. Legislators also need to encourage generic competition for biological drugs and allow the government to negotiate lower prices with drugmakers for supplying federal programmes such as Medicare, it adds.