Childhood-onset mental disorders in six regions of China: a systematic review and meta-analysis of the prevalence and data coverage of attention deficit hyperactivity disorder, conduct disorder, and autism spectrum disorders

Previous systematic reviews of childhood-onset mental disorders in China have focused on country-level prevalence data. We conducted a systematic review summarising the geographical variations in prevalence and data coverage of attention deficit hyperactivity disorder, conduct disorder, and autism spectrum disorders across China. We searched for peer-reviewed articles in PubMed, Embase, PsycINFO, and the China National Knowledge Infrastructure. We used the following inclusion criteria: original research from January, 1980, to June, 2017, set in mainland China, Hong Kong, or Macao; selection by probability sampling on data from the general population; disorders defined according to the Diagnostic and Statistical Manual of Mental Disorders (DSM), the International Classification of Diseases (ICD), or the Chinese Classification of Mental Disorders (CCMD); validated diagnostic tools administered by a psychiatrist or trained lay interviewer; and period or point prevalence estimates within the past 12 months (and point prevalence estimates included in the analysis). We excluded specific or high-risk populations that were not representative (eg, refugees, patients, and ethnic minority groups). Other exclusion criteria were: studies reporting lifetime prevalence estimates (to avoid recall bias); unclear sampling methodology; studies that duplicated or repeated data already in the review (eg, multiple studies using the same data source); and studies that did not report empirical data or prevalence of single disorders under investigation. Meta-regression was performed to investigate whether geographical region is associated with variation in disease prevalence estimates. Data coverage for each disease was calculated by assessing the total age range covered by available data, and multiplying the proportion of this age range that was represented by each study with the proportion of the province or city's population represented by the study (using data from the China Statistical Yearbook 2017). We identified 59 eligible studies. Meta-regression showed that geographical location was associated with variation in disease prevalence estimates. In particular, results of subgroup analysis showed that northeast China reported lower prevalence of attention deficit hyperactivity disorder than the north (β=0·40, p