Orphanet Journal of Rare Diseases (Jan 2020)

Outcomes in pediatric studies of medium-chain acyl-coA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU): a review

  • Michael Pugliese,
  • Kylie Tingley,
  • Andrea Chow,
  • Nicole Pallone,
  • Maureen Smith,
  • Alvi Rahman,
  • Pranesh Chakraborty,
  • Michael T. Geraghty,
  • Julie Irwin,
  • Laure Tessier,
  • Stuart G. Nicholls,
  • Martin Offringa,
  • Nancy J. Butcher,
  • Ryan Iverson,
  • Tammy J. Clifford,
  • Sylvia Stockler,
  • Brian Hutton,
  • Karen Paik,
  • Jessica Tao,
  • Becky Skidmore,
  • Doug Coyle,
  • Kathleen Duddy,
  • Sarah Dyack,
  • Cheryl R. Greenberg,
  • Shailly Jain Ghai,
  • Natalya Karp,
  • Lawrence Korngut,
  • Jonathan Kronick,
  • Alex MacKenzie,
  • Jennifer MacKenzie,
  • Bruno Maranda,
  • John J. Mitchell,
  • Murray Potter,
  • Chitra Prasad,
  • Andreas Schulze,
  • Rebecca Sparkes,
  • Monica Taljaard,
  • Yannis Trakadis,
  • Jagdeep Walia,
  • Beth K. Potter,
  • Canadian Inherited Metabolic Diseases Research Network

DOI
https://doi.org/10.1186/s13023-019-1276-1
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 15

Abstract

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Abstract Background Inherited metabolic diseases (IMDs) are a group of individually rare single-gene diseases. For many IMDs, there is a paucity of high-quality evidence that evaluates the effectiveness of clinical interventions. Clinical effectiveness trials of IMD interventions could be supported through the development of core outcome sets (COSs), a recommended minimum set of standardized, high-quality outcomes and associated outcome measurement instruments to be incorporated by all trials in an area of study. We began the process of establishing pediatric COSs for two IMDs, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU), by reviewing published literature to describe outcomes reported by authors, identify heterogeneity in outcomes across studies, and assemble a candidate list of outcomes. Methods We used a comprehensive search strategy to identify primary studies and guidelines relevant to children with MCAD deficiency and PKU, extracting study characteristics and outcome information from eligible studies including outcome measurement instruments for select outcomes. Informed by an established framework and a previously published pediatric COS, outcomes were grouped into five, mutually-exclusive, a priori core areas: growth and development, life impact, pathophysiological manifestations, resource use, and death. Results For MCAD deficiency, we identified 83 outcomes from 52 articles. The most frequently represented core area was pathophysiological manifestations, with 33 outcomes reported in 29/52 articles (56%). Death was the most frequently reported outcome. One-third of outcomes were reported by a single study. The most diversely measured outcome was cognition and intelligence/IQ for which eight unique measurement instruments were reported among 14 articles. For PKU, we identified 97 outcomes from 343 articles. The most frequently represented core area was pathophysiological manifestations with 31 outcomes reported in 281/343 articles (82%). Phenylalanine concentration was the most frequently reported outcome. Sixteen percent of outcomes were reported by a single study. Similar to MCAD deficiency, the most diversely measured PKU outcome was cognition and intelligence/IQ with 39 different instruments reported among 82 articles. Conclusions Heterogeneity of reported outcomes and outcome measurement instruments across published studies for both MCAD deficiency and PKU highlights the need for COSs for these diseases, to promote the use of meaningful outcomes and facilitate comparisons across studies.

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