If the doctor is working with an inaccurate medication list it is possible the therapeutic decision could be based on faulty information. This simply cannot help improve patient outcomes.
In addition to the challenges of keeping a chart up to date, the fact is that patient self-reported data is rarely 100% accurate. It takes time and expertise to discover the true list of all the substances a patient is or is not taking.
And the simple reality is that they tell their pharmacist things that they won’t tell their doctor.