Do you think they used the term "chronic" instead of "complex" in reference to the time you have been enduring this condition/disease? I've noticed many doctors will add "chronic" to diagnostic terminology when the condition/symptoms last longer than 6 months. Certainly it adds to the confusion but, I wouldn't lose any sleep over it as the ICD billing codes (at least here in the US) is what is relied upon more than the actual diagnostic term itself. You can ask your doctors billing office or insurance company what diagnostic ICD codes your doctor is using and then look it up to see what it refers to, to give you peace of mind or a better understanding of what your doctor is referring to by the name he/she uses.