How many patients hadn't undergone a medical examination until at least a year following their initial hospital visit?
hadn't undergone a medical examination until at least a year refers to SUBTRACT(year(`Examination Date`), year(`First Date`)) > = 1
SELECT COUNT(DISTINCT T1.ID) FROM Patient AS T1 INNER JOIN Examination AS T2 ON T1.ID = T2.ID WHERE T1.Admission = '+' AND STRFTIME('%Y', T2.`Examination Date`) - STRFTIME('%Y', T1.`First Date`) >= 1