Sayal Kapil, Chudal Roshan, Hinkka-Yli-Salomäki Susanna, Joelsson Petteri, Sourander Andre
Division of Psychiatry and Applied Psychology, School of Medicine, University of Nottingham, Nottingham, UK; CANDAL (Centre for ADHD and Neurodevelopmental Disorders across the Lifespan), Institute of Mental Health, Nottingham, UK.
Department of Child Psychiatry, University of Turku, Turku, Finland; Department of Child Psychiatry, Turku University Hospital, Turku, Finland.
Lancet Psychiatry. 2017 Nov;4(11):868-875. doi: 10.1016/S2215-0366(17)30394-2. Epub 2017 Oct 9.
Findings are mixed on the relationship between attention-deficit hyperactivity disorder (ADHD) and younger relative age in the school year. We aimed to investigate whether relative age is associated with ADHD diagnosis in a country where prescribing rates are low and whether any such association has changed over time or relates to comorbid disorders (eg, conduct disorder [CD], oppositional defiant disorder [ODD], or learning disorder [LD]).
We used nationwide population-based registers to identify all Finnish children born between Jan 1, 1991, and Dec 31, 2004, who were diagnosed with ADHD from age 7 years onwards (age of starting school). We calculated incidence ratios to assess the inter-relations between relative age within the school year, age at ADHD diagnosis, and year of diagnosis (1998-2003 vs 2004-11).
Between Jan 1, 1998, and Dec 31, 2011, 6136 children with ADHD were identified. Compared with the oldest children in the school year (ie, those born between January and April), the cumulative incidence of an ADHD diagnosis was greatest for the youngest children (ie, those born between September and December); for boys the incidence ratio was 1·26 (95% CI 1·18-1·35; p<0·0001) and for girls it was 1·31 (1·12-1·54; p=0·0007). The association between relative age and age at ADHD diagnosis reflected children diagnosed before age 10 years, and the strength of this association increased during recent years (2004-11). Thus, compared with children born between January and April, for those born between May and August, the ADHD incidence ratio was 1·37 (95% CI 1·24-1·53; p<0·0001) and for those born between September and December, the incidence ratio was 1·64 (1·48-1·81; p<0·0001). The relative age effect was not accounted for by comorbid disorders such as CD, ODD, or LD.
In a health service system with low prescribing rates for ADHD, a younger relative age is associated with an increased likelihood of receiving a clinical diagnosis of ADHD. This effect has increased in recent years. Teachers, parents, and clinicians should take relative age into account when considering the possibility of ADHD in a child or encountering a child with a pre-existing diagnosis.
Academy of Finland, Finnish Medical Foundation, Orion Pharma Foundation, Finnish Cultural Foundation.
关于注意力缺陷多动障碍（ADHD）与学年中相对较小年龄之间的关系，研究结果不一。我们旨在调查在一个ADHD处方率较低的国家，相对年龄是否与ADHD诊断相关，以及这种关联是否随时间变化或与共病障碍（如品行障碍[CD]、对立违抗性障碍[ODD]或学习障碍[LD]）有关。
我们使用全国基于人群的登记册，识别出所有在1991年1月1日至2004年12月31日之间出生、从7岁起（上学年龄）被诊断为ADHD的芬兰儿童。我们计算发病率比，以评估学年内相对年龄、ADHD诊断年龄和诊断年份（1998 - 2003年与2004 - 2011年）之间的相互关系。
在1998年1月1日至2011年12月31日期间，共识别出6136名患有ADHD的儿童。与学年中年龄最大的儿童（即1月至4月出生的儿童）相比，年龄最小的儿童（即9月至12月出生的儿童）ADHD诊断的累积发病率最高；男孩的发病率比为1.26（95%CI 1.18 - 1.35；p<0.0001），女孩为1.31（1.12 - 1.54；p = 0.0007）。相对年龄与ADHD诊断年龄之间的关联反映了10岁前被诊断的儿童，且这种关联在近年来（2004 - 2011年）有所增强。因此，与1月至4月出生的儿童相比，5月至8月出生的儿童ADHD发病率比为1.37（95%CI 1.24 - 1.53；p<0.0001），9月至12月出生的儿童发病率比为1.64（1.48 - 1.81；p<0.0001）。相对年龄效应不受CD、ODD或LD等共病障碍的影响。
在一个ADHD处方率较低的医疗服务体系中，相对较小的年龄与获得ADHD临床诊断的可能性增加相关。这种效应近年来有所增强。教师、家长和临床医生在考虑儿童患ADHD的可能性或遇到已有ADHD诊断的儿童时，应考虑相对年龄因素。
芬兰科学院、芬兰医学基金会、奥立安制药基金会、芬兰文化基金会。
