Medicaid spending is rising even though enrollment is flat, according to the Kaiser Family Foundation’s annual survey of state Medicaid directors.

Why it matters: This is unusual. Historically, enrollment is the key driver of overall Medicaid spending, and the two have tended to rise or fall roughly in tandem.

Why it’s happening: Enrollment is flat largely because the economy is doing well. Medicaid’s rolls generally swell during a recession; low unemployment keeps the program steady.

• Spending growth is outpacing enrollment growth because of high prescription drug costs, Kaiser says, particularly drugs to treat hepatitis and HIV.
• Many states have also bolstered their coverage for mental health and addiction treatment services, in light of the opioid crisis.

What we’re watching: Enrollment is being pulled in both directions.

• Red states’ embrace of work requirements will shrink their Medicaid programs.
• But a combination of ballot initiatives and competitive governor’s races this year could bring more states into the Affordable Care Act’s Medicaid expansion, potentially causing an enrollment bump in 2019 or 2020.