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Table 2 Characteristics of the eligible studies

From: Status of nutrients important in brain function in phenylketonuria: a systematic review and meta-analysis

Study design
 Observational studies 58
 Intervention studies 7
Countries of origin
 European 48a
 USA 9
 Rest of the world 8
Age groups of subjects
 Children (< 14 yrs) only 24
 Children and adolescents (< 19 yrs) only 15
 Adults only 7
 Mixed age group (infants/children, adolescent and adults) 19
 Classical PKU only 26
 Classical and moderate PKU 5
 Insufficient details to determine sub-classifications of PKU 34
Information on dietary control
 Information on dietary control providedc 54
 Information on dietary control not provided 11
Information on phe-free PS
 Information on PS providedd 36
 Information on PS not provided 29
  1. Notes: a3 Austria, 1 Czech Republic, 2 France, 9 Germany, 7 Greece, 3 Italy, 2 The Netherlands, 2 Poland, 1 Portugal, 1 Russia, 11 Spain, 1 Switzerland, 3 Turkey and 2 UK.
  2. b3 Japan, 2 Brazil, 1 Australia, 1 China and 1 Lebanon.
  3. cEither details of baseline Phe control at entry provided or the study entry criteria required that patients had to be well-controlled.
  4. dEither information detailing the specific PS used by patients or whether a supplementary source of the nutrients that were the subject of this review were taken by PKU subjects.
  5. Data in bold is highly significant