| Methods |
Randomised triple‐blind cross‐over controlled study.
Duration 10 weeks. |
| Participants |
9 participants with PKU (3 males, 6 females, mean age 14.4 years). Low phenylalanine diet commenced early infancy. On relaxed diet prior to study. |
| Interventions |
All participants returned to a low‐phenylalanine diet for the duration of the study. Participants ingested 3 to 4 capsules per day, each containing 500 mg L‐phe during the treatment phase or 500 mg L‐alanine during the control phase. |
| Outcomes |
Blood phenylalanine levels.
The following neuropsychological assessments were carried out at baseline and after the first and second phase: WISC‐R, Rosner's auditory analysis test; Raven's coloured progressive matrices; memory for designs; target test; wide range achievement test (arithmetic subtest); finger agnosia; simple reaction time test; choice reaction time test; grooved pegboard test; trail making tests; underlining test; verbal fluency; Stroop colour word interference test. |
| Notes |
2 participants had continued on a phenylalanine‐restricted diet prior to commencing the study. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Unclear risk |
Method of randomisation not given. |
| Allocation concealment? |
Unclear risk |
Not discussed. |
| Blinding?
Participants |
Low risk |
Triple‐blinded. Participants continued on their usual diet but with the phenylalanine content of the diet manipulated by using additional supplements. |
| Blinding?
Clinicians |
Low risk |
Triple‐blinded. |
| Blinding?
Outcome assessors |
Low risk |
Triple‐blinded. |
| Incomplete outcome data addressed?
All outcomes |
Low risk |
Intention‐to‐treat analysis was employed. |
