Markov chain Monte Carlo estimates of regression weights, corresponding event rate ratios (exponential of regression weights) and 95% event estimate credible intervals.

The 3-level Poisson mixed-effect model included 12,444 level-1 units (incidence counts for two diseases), 3,111 Level-2 units (counties), and 51 level-3 units (states). The table is designed to mirror Figure 1: fixed-effect parameter estimates for autism spectrum disorders (AU) are followed by the corresponding estimates for intellectual disability (ID). For each group of diseases the first parameter listed (AU and ID, respectively) is the intercept. The rest of the fixed-effect parameters are ordered from the strongest negative effect to the strongest positive effect, as in Figure 1. Abbreviations: AU – autism spectrum disorders; ID – intellectual disabilities; AmInd – proportion of American Indians; Asian – proportion of Asians; WHisp – White Hispanics; W – White non-Hispanic; BHisp – black Hispnics; B – black non-Hispaic; Pacific – Pacific Islanders; Insured – proportion of insured; Poor – proportion of poor; Urban – proportion of urban; CongMrepM – congenital malformations excluding malformations of genitals in males; ConGenM – congenital malformations of genitals in males; Viral_M – viral infections affecting males; ASD – inclusion of Autism Spectrum Disorders; CFR – Code of Federal Regulations; DSM – requirement of reference to Diagnostic and Statistical Manual of Mental Disorders; Eval – rigor of evaluation of diagnosis veracity. The regulations were encoded in the following way (23). For CFR: Code −1 if criteria included information from the autism section of CFR only, and +1 if the criteria incorporated additional non-CFR information. For DSM: Code −1 if the entire DSM-IV-TR criteria were used, and +1 otherwise. For ASD: −1 if autism spectrum disorders were included in diagnostic criteria, and +1 if they were not included. For Eval: −1 if a diagnosis by a pediatrician or clinician was mandatory, 1 if a diagnosis of autism or autism spectrum disorders by a pediatrician or clinician was mandated, and 2 if no requirements in addition to those mandated by the Individuals with Disabilities Education Act were added.