MySQL Check If Exists, if Not insert

I am new in MySQL. I am trying to create a procedure to get the row count. If zero, it will insert. If existing, get values of specific column in the table.

Once I store the value in ITEMCOUNT, how can I compare if this is <1?

DELIMITER //

    CREATE PROCEDURE UserCheck (
        in VARIABLE_A VARCHAR(32))

    BEGIN

    DECLARE ItemCount INT(10);

    SELECT COUNT(*) INTO ITEMCOUNT FROM TABLE WHERE ACCEPTED_BY = 'VARIABLE_A';

    IF ITEMCOUNT < 1 THEN INSERT TO TABLE
    ELSE SELECT COLUMN_B IS TRUE
    END IF;

    END //

    DELIMITER  ;

Thanks,

Dave