A Cross Sectional Study to Explore the Cases of red and amber lights whilst on clozapine in SLaM and to determine if those people also had low white counts when not on clozapine.

This study aims to find out the prevalence of patients on clozapine who have to stop it because of low white cell count. We also hope to determine what proportion of that group had white counts in the amber or red range before the start of clozapine treatment and continued to 3 months after discontinuation of clozapine; and to know how long these patients had been on clozapine before the red light warning occurred.