Related: How best-in-class employers control health care costs

According to the findings, most employees lack basic understanding of how health plans work, how to choose the most appropriate plan and how to use health coverage effectively, leading them to choose other options than HDHPs. Says the report, "Employees' health care illiteracy—coupled with their concerns about privacy—have led to lower utilization of employer-sponsored benefits like HDHPs and wellness programs."

Findings also indicate that voluntary benefits are popular, but the types of voluntary benefit offerings is shifting. Among the top offerings in 2018 are supplemental life insurance, legal services, critical illness insurance and identity theft protection, but two of 2017's most popular voluntary benefits have fallen in prevalence. Supplemental life insurance fell 38 percent in prevalence since last year, and accidental death and dismemberment coverage dropped by 32 percent. The change is possibly due to more employers offering these coverages as part of their ERISA plans, according to the report.

Specialty drug costs, it adds, are stable—for now—with the median copay for specialty drugs rising just three percent from last year. That could change this year, however, with specialty drug costs expected to rise by nearly 18 percent in 2018, and with specialty drugs projected to represent half of all drug sales by 2020. That means that employers will have to be on the lookout for ways to manage cost increases and utilization.

One big boost is telemedicine, with 55 percent of employers offering it as part of at least one of their health care offerings; that's an increase from a tad over a third of employers in 2017. In addition, many organizations are covering telemedicine in full, at either 100 percent or for a $0 copay. The rise may be thanks to increasing employee interest in the program, coupled with state law changes that have eliminated known barriers to adoption. And median copays have gone down a bit for telehealth providers, now being on part with that for a traditional office visit—in the neighborhood of $20—to encourage their use.

One other thing that's falling: incentives for wellness participation. In 2017, more than half of employers offered wellness incentives, but now less than a third are. Employers may fear the future legality of such plans, in addition to still having questions about how valuable wellness incentives actually are in controlling costs and improving health.

The elimination of the individual mandate could make 2019 "very interesting," according to Brian Kropp, HR practice leader at Gartner, who said in a statement, "We could see employers drop coverage, which could result in lost productivity should their employees become ill or injured. Or we could see employers pass increased premiums onto employees, which might cause employees to drop coverage and force organizations to absorb the increases and take a hit to their bottom lines. To get ahead of these challenges, employers are going to need to get creative in the ways they control costs."