The annual review of internal QC is performed to answer two questions:

1. What is the quality (random and systematic effects) currently in the laboratory? Has the quality significantly changed?
2. Are control limits and central line in the control chart still optimal for detecting situations out of control?

Guidance for this is difficult to give but a general approach is given in the Trollbook (Nordtest TR569) chapter 10 and in example 8 is presented in detail the statistical calculations

In the annual review you should also look at your PT data.