Table 1.
Summary of characteristics of included studies
| Study ID | Location | Study design (Period) | Participants (Gender, male%) | Age range in years (Mean ± SD) | Definition of ADHD symptoms | Allergic diseases types | Outcome measurements |
|---|---|---|---|---|---|---|---|
| Chen 2013 [33] | Taiwan | Case-control (1996-2010) |
N = 39, 880 ADHD: n = 5811; Tic alone: n = 1816; ADHD and Tic: n = 349; general population n = 31,904 (76%; 77.4%) |
ADHD: (15 ± 81) Control: (17 ± 17) | ADHD was diagnosed according to ICD-9-CM code by psychiatrists. | • Asthma • Allergic rhinitis • Atopic dermatitis • Allergic conjunctivitis |
Allergic diseases were classified according to ICD-9-CM codes by internists/pediatrician. |
| Hak 2013 [34] | UK | Nested case-control (1996-2006) |
N = 4, 420 ADHD: n = 884; control: n = 3536 (Restricted to male only) |
4 to14 years | Based on medical records of first-time diagnosis of ADHD (at least one recorded prescription of ADHD drug) | • Asthma • Allergic rhinitis • Atopic dermatitis • Any atopic disorder • Unspecific allergies • Food allergy • Cow’s milk intolerance |
Diagnoses of atopic disorders, asthma were done based on codes recorded on medical histories |
| Kwon 2014 [36] | Korea | Cross sectional (not specified: data collected all year long) |
N = 4113 ADHD: n = 549; control: n = 3564 (75.2%; 47.9%) |
7 to 8 years | Diagnosed according to DSM-IV criteria, together with epidemiological questionnaires Computerized Attention Deficit-Hyperactivity Disorder Diagnostic System, the abbreviated Conner’s Parent Rating Scale (CPRS), and DuPaul’s ADHD Rating Scales. | • Asthma • Allergic rhinitis • Atopic dermatitis • Allergic conjunctivitis • Food allergy Drug allergy |
Measured by questionnaires, International Study of Asthma and Allergies in Children (ISAAC), for asthmatic symptoms/skin rashes/sneezing |
| Romanos 2010 [37] | Germany | Retrospective cross sectional (2003-2006) |
N = 13, 318 ADHD: n = 653; control: n = 12,665 (79.6%; 48.4%) |
3 to 17 years | Medical examination according to ICD-10 criteria and standardized parental interviews. | • Asthma • Allergic rhinitis • Atopic eczema |
Self reported and medical examination |
| Suwan 2011 [35] | Thailand | Case-control (January-November 2010) |
N = 80 ADHD n = 40; control n = 40 (77.5%; 77.5%) |
5 to15 years | Diagnosed according to DSM-IV criteria by pediatrician | • Asthma • Allergic rhinitis • Eczema • Allergic conjunctivitis • Urticaria • Food allergy |
Evaluated by history and physical examination and skin prick tests |