Parillo’s recommendations are pretty straightforward. Physicians must computerize their billing systems, she said. They must carefully review the bills they send out and the payments that insurers send back. They must hire office personnel to deal with the insurance companies. A well-run office can get the insurer’s rejection rate down from 30 percent to, say, 15 percent. That’s how a doctor earns money, she told me. It’s a war with insurance, every step of the way.