The findings reported by Lieke Wijnhoven and colleagues  observing that "children with ASD [autism spectrum disorder] have a high risk to have co-occurring anxiety symptoms" are not likely to win any awards in relation to novelty. Most people, I assume, with some knowledge about autism will know that anxiety seems to be a quite consistent 'partner' to the label both in children and adults, and can for some, be absolutely disabling (see here).
But that's not to say that the Wijnhoven findings aren't important; as authors describe results both giving "an overview of the prevalence of anxiety symptoms in a clinical Dutch sample of children with ASD" and also examining "age, gender, ASD subtype, and IQ as potential risk factors for anxiety" in their sample of over 170 children diagnosed with an ASD.
Using a participant group already signed up for a "randomized controlled trial (RCT) testing the effect of an anxiety intervention for children with an ASD" , researchers analysed their responses to the Spence Children’s Anxiety Scale for Children and Spence Children’s Anxiety Scale for Parents (translated into Dutch). They also relied on data from cognitive testing, and just for good measure, added in data on the various comorbid diagnoses held by their participant group: "attention deficit hyperactivity disorder (45.3%), (persistent) depressive disorder (7.0%), oppositional defiant disorder (3.5%), obsessive–compulsive disorder (1.7%), reactive attachment disorder (1.7%), and posttraumatic stress disorder (1.2%)." Yes, those figures do put attention-deficit hyperactivity disorder (ADHD) at being present in over 45% of participant cases (see here).
Results: "In total, 66.3% of the participating children with ASD had child-rated subclinical or clinical anxiety symptoms on the total scale and/or on at least one subscale and 81.4% of the participating children with ASD had parent-rated subclinical or clinical anxiety symptoms on the total scale and/or on at least one subscale." Yep, just as you and I suspected, anxiety symptoms whether clinical or sub-clinical, are pretty rife in relation to autism. Additionally, girls seemed to present with more anxiety symptoms than boys; particularly when it came to "separation anxiety symptoms..., social phobia symptoms..., panic disorder/agoraphobia symptoms..., and generalized anxiety symptoms."
Age was and wasn't an issue, insofar as total anxiety symptoms being more 'intensely' reported for younger children than older children but: "Age was not a significant predictor of social phobia symptoms, specific phobia symptoms, panic disorder/agoraphobia symptoms, and generalized anxiety symptoms" based on child ratings. A similar pattern was also seen for parent-reports too.
What's more to say? Well, very little really. Anxiety once again, turns up as a frequent 'comorbidity' (if I can still - Mildred Creak - call it just comorbidity) and the challenges remain as to what can be done to minimise it and its effects (see here). Here's to hoping...
 Wijnhoven LAMW. et al. Prevalence and Risk Factors of Anxiety in a Clinical Dutch Sample of Children with an Autism Spectrum Disorder. Front. Psychiatry. 2018; March 2; 9: 50.
 Wijnhoven LAMW. et al. The effect of the video game Mindlight on anxiety symptoms in children with an Autism Spectrum Disorder. BMC Psychiatry. 2015 Jul 1;15:138.