You will not be able to implement a productivity-based compensation model without the pitfalls. Like Sharon says, you should focus on quality measures including patient access. By doing so, physicians will be interested in organizing their work flow. Succesfull implementations of LEAN learns us that by focussing on output, you will get an efficient process and consequently good productivity.
A combination of the telephone reminder calls, text messages and e-mail will effective for many patients, especially when you will be able to do it in the language they speak. In addition, you could also consider charging a fee for no shows. My dentist does if you don’t cancel your appointment prior to the scheduled time. Of course these people probably don’t pay either and than the story continues.