First-line care for adults with PTSD, in the Phoenix Australia / NHMRC guidelines, is trauma-focused CBT and EMDR. Hypnotherapy on this page is complementary to that care, not a substitute.
Brom, Kleber and Defares (1989) compared hypnotherapy, trauma desensitisation, and psychodynamic therapy with a wait-list in 112 people. Treated groups had fewer trauma-related symptoms than the wait-list. Differences between the three treatments were small. That study did not make hypnosis first-line care, and it did not report a 75% reduction.
The ABS National Study of Mental Health and Wellbeing (2020-2022) reported that 5.6% of people aged 16-85 had a 12-month post-traumatic stress disorder. There is no verified official 7.8% youth or 15% increase statistic we can cite here.
Norwest Wellbeing's own reported outcomes sit in a 75-85% range for many people within 2-5 sessions. That figure is clinic-reported, not a research finding. Results vary.