Cost sharing for insured adults increased 37 percent per inpatient hospitalization from 2009 to 2013, with variations in insurance policies resulting in a higher burden of out-of-pocket costs for some patients, according to an article published online by JAMA Internal Medicine.

Patients have been increasingly responsible for a growing share of their health care expenditures in out-of-pocket costs as health insurance policies have changed in recent years. Proponents argue this has the potential to reduce overuse and inappropriate care but increased out-of-pocket spending can also impede access to care and affect treatment choices.

Emily R. Adrion, PhD., M.Sc., of the University of Michigan Medical School, Ann Arbor, and coauthors used data from a large commercial health insurance claims database to examine out-of-pocket spending for hospitalizations among nonelderly adults (18 to 64 years old).

The analysis of medical claims for 7.3 million hospitalizations used 2009 to 2013 data from Aetna, UnitedHealthcare and Humana, representing about 50 million members. The nonelderly adults were enrolled in employer-sponsored and individual-market health insurance plans.

Cost sharing per inpatient hospitalization increased 37 percent from $738 in 2009 to $1,013 in 2013. The increase was largely driven by a jump in the amount applied to deductibles, which grew by 86 percent from $145 in 2009 to $270 in 2013, and by increases in coinsurance, which grew 33 percent from $518 in 2009 to $688 in 2013, the authors report.

The study found that adults enrolled in individual market plans and consumer-directed health plans had the highest total cost sharing.

Cost sharing also varied across regions, diagnoses and procedures. For example, the states in 2013 with the highest total cost sharing per inpatient hospitalization were Utah, Alaska and Oregon. Also, out-of-pocket spending associated with emergency hospitalization for heart attack grew by 37 percent to $1,586 and for acute appendicitis by 40 percent to $1,509, the results indicate.

The authors suggest their findings point toward a trend of fewer plans requiring copayments at the time of services and more plans requiring higher coinsurance and deductibles after care is delivered.

The authors note study limitations, including that the study period did not extend far enough to capture the implementation of several provisions of the Affordable Care Act of 2010 that affect benefit design and have implications for out-of-pocket spending.

"With an estimated 85 percent of all commercial health insurance benefit packages requiring coinsurance for inpatient hospitalizations in addition to meeting an annual deductible, cost sharing for inpatient hospitalizations remains an important, if often overlooked, area for policy reform," the article concludes.

In a related editor's note, JAMA Internal Medicine Deputy Editor Mitchell H. Katz, M.D., writes: "To require consumers to pay large amounts of out-of-pocket expenses for health care may lead to delay or foregoing of needed care or to financial ruin, the latter of which insurance is supposed to protect you against. There are no easy answers for how to deal with the rising cost of medical care, but increasing out-of-pocket spending for unavoidable, necessary care is counter to the goals of a health insurance system."