Page 38 - Demo

Chapter 236as dependent variables in addition to the target behavior used to evaluate transfer effects of the intervention to a broader domain of functioning including other behaviors or settings.15 A generalization measure could be an assessment of the same behavior in different settings or a measurement of an interventional effect on a completely different behavior. These should be identified a priori and measured throughout all phases. Strengths, limitations, and recommendations noted by the author(s) were collected, and reviewers were asked for additional comments.Data AvailabilityThe search strategy and data extraction sheet are available on request to the first author.ResultsOf 18,483 identified citations, 12 studies met the inclusion criteria, summarized in Table 2. One article reported on 2 different N-of-1 studies with divergent methodological characteristics.25Study CharacteristicsInstitutional ethics approval was explicitly mentioned in 8 studies.PopulationThe 12 included studies had an average of 5 participants with an average age of 21 (range 3–63) years (Table 2). The majority of the studies (n = 7) did not define the eligibility criteria.InterventionVarious types of interventions were applied: psychological therapy (n = 4), dietary supplement (n = 4), drug (n = 3), and dietary therapy (n = 2; Table 2). One study combined 2 subsequent interventions.25 Only some dietary interventions might be categorized as disease modifying including phenylalanine restriction and folic acid and L-arginine supplementation,25–28 although distinction was difficult due to vague Annelieke Muller sHL.indd 36 14-11-2023 09:07