We included in our study children with ASD who were part of the PARIS study, conducted by the Excellence Centre for Autism & Neuro-developmental Disorders (InovAnd) at the Robert Debré Hospital between March 2017 to April 2021. This study was approved by the local ethics committee (2021-27 N° IDRCB: 2021-A00489-32). Informed consents were obtained before enrollment in the study.
All participants were screened using a parental semi-structured interview for medical history. The final diagnosis of ASD was performed according to DSM-5 criteria (3) by summing up the information from the Autism Diagnostic Interview-Revised (17), the Autism Diagnostic Observation Schedule -2nd edition (ADOS-2) (18) and clinical records of the individuals. Pre- and peri- natal history was evaluated through a direct semi-structured interview with the mother of each child enrolled in the study. We paid a specific attention to a history of MIA by scrutiny explore any diagnosed immune mediated illnesses which could have occurred during pregnancy. Based on this information, children were then split either in MIA (MIA+) or in non-MIA (MIA-) sub-groups. We considered mothers with a significant history of a MIA-related event during pregnancy when they were: (i) with an autoimmune disease as listed by the American Autoimmune Related Diseases Association: https://www.aarda.org/diseaselist. The disease should have occurred during the first or the second trimester of pregnancy, or was present before the pregnancy and had a flare-up requesting a treatment adjustment during pregnancy; (ii) with a viral or bacterial infection during pregnancy with a fever over 38.5°C for more than 24 hours. Occurring during the first or the second trimester of pregnancy. Mothers with an infection resulting from a pathogen with a well-documented direct brain cytopathic effect (such as cytomegalovirus infection) were excluded (iii) with gestational diabetes. We only considered mothers requiring insulin supplementation. We considered that this condition was more likely to be associated with a significant systemic metabolic inflammation .
Neutrophil to lymphocyte ratio
Routine blood counting was performed using XN 3000 (Sysmex) NLR was then calculated by dividing the absolute value of the neutrophil count by the absolute value of the lymphocyte count. In the categorical analysis, a NLR greater than 3 was considered as pathological (19).
For demographic / perinatal events in the MIA+ versus MIA- sub-groups, we used independent-sample t-tests, Fisher tests or Chi-square tests, as appropriated. For the univariate analysis, lymphocyte and neutrophil counts in MIA+ versus MIA- were compared using t-test.
In linear models, age was associated with lymphocytes (R2=0.04, p=0.0009), neutrophils (R2=0.02, p=0.01) and NLR (R2=0.03, p=0.004) in a U-shaped curve (supplementary figure 1). The multivariate analysis was thus adjusted on age, age2, sex, pregnancy complications (placenta previa and maternal-fetal infections) and ADHD co-morbidity, known to affect NLR (16,20–22). Statistical analysis was performed using R studio version 1.3.1093.