What is the significance of an hs-crp of 15+?

Cardiac risk marker? I agree with dr. Bowers that c-reactive protein is non-specific. But all else being equal, an elevated CRP does correlate with elevated cardiac risk. So, for example, in someone with a borderline cholesterol reading, a high CRP might suggest a need for drug treatment.
Very significant. It's even more significant when present with multiple risk factors for coronary heart disease, or in pts. With established cad.
Hard to say. C-reactive protein is a nonspecific marker of inflammation. It can be elevated in any condition that has an inflammatory component like infections or arthritis. It can also be elevated in obesity, chronic renal failure, cigarette smoking and many other apparently noninflammatory states. So an elevated CRP doesn't really mean much without other clinical information.