Here is what I do at my lab.
1. IF YOU HAD A SPLIT NIGHT STUDY- FOLLOW UP TITRATION 6 MONTHS TO 2 YEARS. (Depending how you feel.)
2. IF YOU HAD FULL NIGHT CPAP STUDY- 2 TO 5 YEARS. ( Depending on how you feel.)
After that, every 5-7 years you should get a new one, as you qualify for a new CPAP, its good to get another one done. Remember, you can find labs that offer portable studies that can atleast show how you are doing at your current pressure anytime. These studies cost anywhere from $100 to $1000 depending where you live and how extensive the portable is. We charge $150 for a portable at our lab. Also, always make sure they give you a straight answer on what your AHI or RDI (basically how many times you woke up from respiratory events and how many you had per hour) at the final pressure. Its important to know if they left off at a pressure that is suitable for you.