The presidential hopefuls aren't the only ones eyeing health-care issues for 2020. Large employers are putting together benefit plans for next year, and they are expecting the rise in employee health costs to hit a four-year high, in part, due to rising drug prices.

Private employer medical costs are projected to increase by an average of 6% next year, after averaging about 5.5% annually over the last three years, according to PwC Health Research Institute's annual Medical Cost Trend survey of more than 500 of the nation's largest employers.

The jump in spending is being attributed to expensive specialty drugs that weren't available a few years ago. Researchers say spending on specialty medications to treat cancer and other complex diseases now makes up more than 40% of overall employer drug spending.

"The portion of the pie that goes to specialty drugs is growing and has grown substantially, so that's one big reason why we think there'll be a big uptick in drug spending over the next decade," said Ben Isgur, who leads PwC's Health Research Institute.

Drug spending is expected to grow more than 3% next year, and that growth rate is expected to double by 2023. While still well below the 13% spike in costs following the introduction of new hepatitis C drugs in 2014, the trend has employers looking to get ahead of increases.