Is it necessary to sterilize your CPAP?

I have been fielding a lot of questions lately about the new gadget on the market that sterilizes your CPAP machine.  Patient's want to know if 1) the CPAP sterilizing machine works 2) if CPAP sterilizing machines prevent infection and 3)if health insurance plans pay for the machine.  
CPAP sterilizing machines do work.  The most popular version on the market generates ozone which circulates through the CPAP unit.  Ozone is bactericidal. White vinegar is also bactericidal.  I will never forget when I was a medical student rotating through the vascular surgery service at the VA.  Every morning we would change dressings on veterans with chronically infected leg wounds.  The wounds would be weeping pus even after several weeks of oral or IV antibiotics.   The medical students were responsible for changing out wound dressings that were soaked in a diluted vinegar solution.  In a couple days the wounds would be clean. If vinegar can take care of those wounds with hospital bacteria, it can certainly keep a home CPAP clean.  This is why we instruct our patients to wash personal CPAP with a dilute vinegar solution once a week.  
I have been practicing sleep medicine for over 15 years now.  I have never known a person to get an infection from their CPAP machine - and I have seen some nasty CPAP machines. There have been multiple occasions I have discovered roaches in CPAP machines brought to clinic (yes - some alive).  I have seen countless machines with mold growing inside of the water chamber.  Filthy masks are a daily occurrence.  I have not diagnosed one infection from CPAP.  I decided to do a literature search and did not find any medical research documenting evidence of infection being spread by a personal CPAP machine.  In fact the only paper I found on the topic suggests personal CPAP machines do not cause infection.   It is important to note a difference between a personal CPAP machine and a CPAP machine in a hospital that is used by multiple people.  Personal CPAP machines are used by one person only.  People do not catch diseases from themselves - they catch infectious diseases from other people or things.  If your immune system becomes compromised you can certainly get an infection from the bacteria that are always on your body but that is different than transmitting an infection.  Hospital CPAP machines are used over and over again by multiple different people and have been shown to harbor infection. Anything that is in a hospital can harbor an infection and should be sterilized between uses.  
I can promise you insurance companies do not pay for CPAP sterilizing machines.  The units cost about $300.
Do I recommend everyone get a CPAP sterilizing machine?  I do not.  Do I recommend keeping your CPAP clean?  I do.  Patients do find the CPAP sterilizing machines more convenient.  If the convenience is worth the price tag by all means get one.  If you are getting one because you think you need to sterilize your CPAP machine nightly then think again.  Then you also need to sterilize your pillow case because the same germs that end up on your CPAP are also on your pillow case.