A community treatment order shall remain in force until—
the period mentioned in section 20A(1) below (as extended under any provision of this Act) expires, but this is subject to sections 21 and 22 below;
the patient is discharged in pursuance of an order under section 23 below or a direction under section 72 below;
the application for admission for treatment in respect of the patient otherwise ceases to have effect; or
the order is revoked under section 17F below,
whichever occurs first.