Insurers must cover certain preventive services, like immunizations, cholesterol checks and screening for breast and colon cancer, at no cost to the consumer if the provider is in their network. But for other services and items, like prescription drugs, marketplace customers often have to meet their deductible before insurance starts to help.

While high-deductible plans cover most of the costs of severe illnesses and lengthy hospital stays, protecting against catastrophic debt, those plans may compel people to forgo routine care that could prevent bigger, longer-term health issues, according to experts and research.

“They will cause some people to not get care they should get,” Katherine Hempstead, who directs research on health insurance coverage at the Robert Wood Johnson Foundation, said of high-deductible marketplace plans. “Unfortunately, the people who are attracted to the lower premiums tend to be the ones who are going to have the most trouble coming up with all the cost-sharing if in fact they want to use their health insurance.”

Deductibles for the most popular health plans sold through the new marketplaces are higher than those commonly found in employer-sponsored health plans, according to Margaret A. Nowak, the research director of Breakaway Policy Strategies, a health care consulting company. A survey by the Kaiser Family Foundation found that the average deductible for individual coverage in employer-sponsored plans was $1,217 this year.

In comparison, the average deductible for a bronze plan on the exchange — the least expensive coverage — was $5,081 for an individual and $10,386 for a family, according to HealthPocket, a consulting firm. Silver plans, which were the most popular option this year, had average deductibles of $2,907 for an individual and $6,078 for a family.