Reliable classification of case-control studies of autistic disorder and obstetric complications

Several reports have suggested an association between obstetric complications and autistic disorder. Since conclusions may be drawn from case-control studies, a methodology to identify case-control studies of autistic disorder and obstetric complications for qualitative and quantitative reviews is needed. We sought to establish the feasibility of blinding of reports as a means to remove biases in meta-analyses of case-control studies of autism and obstetric complications. Therefore, we located published reports of case-control studies of autistic disorder and obstetric complications by a literature search and additional articles. The methods or other appropriate portions of the articles were blindly reviewed for the presence or absence of obstetric complications in cases with autistic disorder matched with at least one control without autistic disorder. Good inter-rater reliability was obtained for case-control studies of autistic disorder (74.6% agreement and κ=.451) and for obstetric complications (84.0% agreement and κ=.658).