Three Iwi Māori Partnership Boards are calling for independent advocacy for whānau from the outset of serious incidents, after an 11-year-old was mistaken for an adult, restrained and injected with drugs.

The family of an 11-year-old autistic girl who was mistaken for an adult, restrained and injected with drugs at a Waikato Hospital says it's had a "lasting and traumatic impact".

The girl's mother says she has noticed changes in behaviour since the incident.