Table 2

Characteristics of included studies

Type of study designN=418%
Case report22052.6
Case series307.2
Cohort409.6
Cross-sectional5312.7
Longitudinal92.2
Randomised controlled trial102.4
Retrospective medical record review5412.9
Review20.5
Country of data collection
 Australia153.6
 Canada81.9
 China122.9
 Denmark112.6
 France102.4
 Germany122.9
 India194.5
 Italy163.8
 Japan184.3
 Spain81.9
 Turkey225.3
 UK204.8
 USA14334.2
 Other*10424.9
Decade of publication
 1980s20.5
 1990s276.5
 2000s7618.2
 2010s22052.6
 2020–20249322.2
Age groups†
 Infancy (0–1 years)00.0
 Childhood (2–10 years of age)7918.9
 Adolescence (11–17 years)17942.8
 Mixed age groups (0–17 years)16038.3
Sex
 Males (total N)255634.8
 Females (total N)478265.2
 Studies in which sex was not reported79
  • *Algeria (1), Austria (1), Bangladesh (1), Belgium (1), Bolivia (1), Bosnia (1), Brazil (1), Bulgaria (2), Croatia (2), Czech Republic (1), Egypt (1), Finland (4), Greece (5), Hong Kong (1), Hungary (2), Indonesia (1), Iran (2), Ireland (3), Israel (2), Kenya (1), Korea (6), Lebanon (1), Libya (1), Macedonia (1), Malaysia (4), Mexico (2), Nepal (1), Netherlands (6), New Zealand (1), Nigeria (2), Norway (4), Oman (1), Pakistan (3), Poland (4), Portugal (4), Qatar (2), Saudi Arabia (2), South Africa (2), Sri Lanka (1), Sweden (5), Switzerland (3), Taiwan (3), Thailand (5), Ukraine (2) and multiple countries in Africa (1).

  • †Based on the American Academy of Paediatrics; adolescence is divided into three groups according to this classification but was collapsed into one category for the purposes of this review (>10 years of age). Late adolescence, being 18–21 years of age, was excluded from this study.