Physicians, pharmacists, and staff at Partners HealthCare have created guidelines to help doctors and nurse practitioners make the most cost-effective drug choices for their patients. The guidelines use a color system to denote price classes of drugs. Those that are “green” are the least costly and most favored. Yellow is the second choice and red is last. Patients want to save money on their drugs and less costly drugs help them save on out-of-pocket costs and co-payments. But, such drugs help others, too. They matter to employers who fund health insurance plans. They also matter to providers who have a stake in ensuring that precious health care dollars are spent wisely.