NBER, in examining this strategy, said that it was like other strategies in that it has not significantly changed the trajectory of rising health care costs in the U.S. "Managed care, changes in provider payment methods, and increasing patient cost-sharing have all been shown to have some effect on lowering the level of spending as they are phased in, but, after they have been adopted and diffused, there is strong evidence that spending growth tends to resume its former path," the authors of the study write.

They added that the effect of cost-sharing on privately insured spending growth has not been well-studied, despite growing concerns about the HDHP model.

A model adopted across the industry

High deductibles have become very common among all types of insurance plans. Even the Affordable Care Act's "bronze" plans—the second-most popular plan on that marketplace—have incorporated high deductibles as a prominent feature.

One rationale behind the HDHP model has been the premise that if consumers have more "skin in the game"—that is if they experience health care costs more directly—they will become better-informed about their options and therefore, smarter shoppers.

However, this premise has been challenged in a number of ways. Health care pricing details remain generally opaque for all purchasers, whether they are employer plans or consumers themselves. Questions about quality are difficult for consumers to answer, despite some guidance from Medicare and other sources. And many consumers are located in geographic areas where a choice of providers is limited.

The authors point to data that "…Raise the concern that HDHPs may have high adverse health consequences when patients delay, reduce, or forgo care to curb costs, even when costs are moderate compared to health benefits. Few researchers have investigated the concern that HDHPs may negatively impact vulnerable, disadvantaged populations such as those who are low-income and high risk."

A reduction in levels of spending, but not growth of spending

The researchers looked at both large and small samples of spending among plan members. The findings were somewhat mixed—for example, members who switched from low-deductible plans to high-deductible plans did see lower growth rates of spending, however, the reduction generally did not last for more than one year.

One interesting finding was that HDHP did seem to discourage the use of less cost-effective drugs. The authors write that it is plausible that those with higher-deductible plans have more of an incentive to search for lower-price options, if prices in their area increase but their options on prices overall stay the same. Since drugs can be purchased via-mail order pharmacies, geographic constraints may be less of a factor for consumers—although this point is not addressed by the study.

Overall, the study found HDHPs had no effect on aggregate spending growth for insured plans, but did find a modest but meaningful effect on spending growth for drugs.

"High deductibles do not curb runaway medical spending, but may lead to more selective choices among drugs that better balance health benefits and cost," the report said. "It appears that HDHPs do not have as much potential for long- term cost containment as their advocates contend, nor do they pose as much risk to the use of effective and cost-effective care as their detractors fear."

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