Materials and Methods
Statement – This systematic review of the literature was conducted in the department of the pediatric intensive care at the Emma Children’s Hospital in Amsterdam. The conduct and reporting of this review adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-statement23.
Search – After several scoping searches, three bibliographic databases (PubMed, Embase.com and Clarivate Analytics/Web of Science Core Collection) were searched for relevant literature from inception to September 30th, 2022. Searches were devised in collaboration with a medical information specialist (KAZ). Search terms (including synonyms), closely related words and keywords were used as index terms or free-text words, which were “pediatric intensive care unit” and “inequalities”. The searches contained no date or language restrictions that would limit results. The references of the included full-text studies and relevant systematic reviews were searched for additional relevant literature. Duplicate articles were excluded using the R-package “ASYSD” an automated deduplication tool24, followed by manual deduplication in Endnote (X20.0.3) by the medical information specialist (KAZ). The full search strategy used for each database is detailed in appendix A in the supplementary material. Studies were included if they met the following criteria: patients under the age of 18 years old (excluding premature infants), admission to the PICU with a primary diagnosis based on a respiratory disease, results available on outcome (defined by mortality, PICU LOS and resource use at the PICU (e.g. support of a ventilator)) and studies reviewing health care disparities by socioeconomic factors, insurance status, ethnicity, environmental factors or gender. Exposure to environmental tobacco smoke (ETS) and bad nutritional status can be seen as an indirect effect of economic recession and poverty, therefore we decided to search for articles with smoking and diet as risk factors as well. In addition, studies were excluded if they were of the following publication types: editorials, letters, legal cases or interviews.
Selection process – Two reviewers (TH and BK) independently screened all potentially relevant titles and abstracts for eligibility using the Rayyan software25. If necessary, the full text article was checked for the eligibility criteria. Differences in judgement were resolved through a consensus procedure.
Data assessment – The full text of the selected articles was obtained for further review. Two reviewers (TH and BK) independently evaluated the methodological quality of the full text papers using the critical appraisal skills programme (CASP) checklist26.