In January 1st, 2001, a nursing home had 60 elderly patients: 50 of these developed pneumonia in the year and of these, 20 developed the Acute Respiratory Distress Syndrome within 1 month of the pneumonia. During the year, 4 patients died, all of whom had ARDS. 10 of the 50 pneumonic patients were transferred to other health facilities within 1 month of developing pneumonia, 6 had had ARDS, 4 had not.

Note:

(i). Withdrawals are individuals who are lost to follow-up during the study period. This is assumed to be mid-way through the study period.

(ii). Only pneumonic patients are at risk of ARDS.

calculate: The risk of leaving the nursing home among those that developed pneumonia