Kaiser's mental health and optical workers were joined by nurses in a sympathy strike.

They demanded adequate staffing and protested proposed cuts to retirement and health benefits.

Dylan Roby of the UCLA Center for Health Policy Research says rising health costs are a root cause of many labor disputes these days, even at health care institutions.  

ROBY:  "Health care costs have been going up at about 7-9% per year for a long time now, and we're starting to hit a point where it becomes very difficult for employers to make ends meet, and employees, because they've been suffering from stagnant wages for a long time, can't really absorb that deficiency in their income."

Roby says we're like to keep seeing labor disputes over benefits as long as health care costs are not under control.