Yes, this is known to be true. Studies of oral immunotherapy often show failure rates in the 20-30% range, and nobody knows a way to accurately predict who will succeed and who will fail without actually going through the whole treatment. IgE levels can correlate with success but they are far from a perfect predictor. The other big factor is age. If you can start immunotherapy super early, like in the 0-2 year old range, it is significantly more likely to work.
