PPN Insights to PANDAS IVIG Study
Prophylactic antibiotics may also have impact on PANDAS symptoms.
Also of note, in the blinded portion, there were responders (i.e., subjects who had >30% improvement in symptoms) in both the placebo and the IVIG group. This was unusual as OCD is known to be resistant to placebo effect. The authors comment that this improvement in the placebo group is possibly due to antibiotics which were started at baseline for all participants as prophylaxis. Prophylactic antibiotics are reported in the literature as reducing symptoms in PANDAS.
The blinded IVIG group likely had underreporting of symptom improvement.
There was a >50% mean reduction in symptoms during the open-label IVIG phase when patients and their families knew they were receiving IVIG; however, the IVIG and placebo groups did not differ statistically in the blinded phase of the trial. The authors comment that this lack of expected response in the blinded phase may have been due to a protocol issue that introduced a negative parental bias in reporting as patients were only guaranteed IVIG if symptoms did not show improvement at six weeks. Parents looking for complete remission had an incentive to under-report OCD improvement.
Blood test predictive of symptom improvement in both placebo and IVIG groups.
Finally, there was evidence that high serum anti-nuclear antibodies and CAM Kinase II activation was predictive of symptoms improvement in both the placebo and the IVIG groups. This finding may provide further evidence that antibiotics may be therapeutic to OCD symptoms when these values are elevated.
The paper clearly motivates further study as >60% improvement in OCD symptoms is significant.
KA Williams, SE Swedo, CA Farmer, et al. Randomized, Controlled Trial of Intravenous Immunoglobulin for Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections. Journal of the American Academy of Child & Adolescent Psychiatry, August 6, 2016. http://www.jaacap.com/article/S0890-8567(16)31158-3/pdf