Non-refundable ticket changes will cost you. As of 2013, Delta charges $150 for changes to domestic tickets and $250 for international tickets. If you booked your Delta flight through a travel agent or an online agency, you will be charged an additional $50 to make any changes to your ticket.
In the U.S., approximately 3.3 million people have OCD, of which you have 0.3 to 1% of pediatric population and 2% of adult population. So about 1 out of 200 adults have OCD and twice as many have had OCD at 1 point or another in their life.
It is estimated that between 26.4 million and 36 million people abuse opioids worldwide, with an estimated 2.1 million people in the United States suffering from substance use disorders related to prescription opioid pain relievers in 2012 and an estimated 467,000 addicted to heroin.