To capture all relevant literature on NAFLD among children and adolescents on AAP, we plan to conduct 2 systematic literature reviews. In our first search, we aim to identify studies that assess NAFLD in children and adolescents taking AAP. Given that we expect a paucity in such studies based on a pilot search performed, we will include studies of different designs including cohort and case-control studies, case reports, and case series. In our second systematic search, we will comprehensively review AAP trials in children and adolescents, attempting to identify any reports of NAFLD; we intend to determine whether this was documented as a primary outcome, a secondary outcome, or as an incidental finding in these studies.

Our systematic review will be performed according to this predefined protocol that describes the objectives, search strategy, eligibility criteria, and evaluation methods according to the PRISMA (Preferred Reporting items for Systematic Reviews and Meta-Analysis) guidelines [32].

We will conduct 2 systematic literature reviews. The search is restricted to studies published in English from January 1, 1950, until March 31, 2021. We selected 1950 as the starting year for the literature search, as it coincides with the development of the first antipsychotic.

In our first search, we aim to identify studies that assess NAFLD in children and adolescents taking AAP. We will use the following search terms: “second-generation neuroleptics,” antipsychotics,” and “neuroleptics,” with their generic and brand names given in Table 1. Further, the following variations of pediatric NAFLD, namely “NAFLD,” “NASH,” “nonalcoholic fatty liver disease,” “nonalcoholic steatohepatitis,” “hepatic steatosis,” “fatty liver disease,” “nonalcoholic fatty liver,” and “fatty liver.” In our second search, we will include the following keywords: “atypical antipsychotics” and “atypical neuroleptics” [33].

Medications in combination with Fluoxetine will not be included in the research (ie, Olanzapine: Co-Depricap, Depten-OZ,Rexepi Combi,Symbyax, Tagram, Target, Olapin Forte, Olapin Plus,Olanex F, Oladay-F).

In our second systematic search, we will comprehensively review AAP trials in children and adolescents, attempting to identify any reports of NAFLD; we aim to determine whether this was documented as a primary outcome, a secondary outcome, or as an incidental finding during these studies. The following databases will be used to conduct the search: Ovid MEDLINE, Cochrane, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). We also searched the following databases up to 2016: Embase, Web of Science, BIOSIS Previews, and PsycINFO.

A systematic, computer-assisted search of the following databases will be performed by 4 medical students RH, FN, GA, and MA at the Mohammed Bin Rashid University (MBRU): Ovid MEDLINE, Embase, Web of Science, BIOSIS Previews, PsycINFO, and CINAHL. The search strategy will be supported by librarian Shakeel Tegginmani at the MBRU Library. Furthermore, the bibliographies of the retrieved and relevant articles will be manually searched for relevant articles. Full articles in English published in peer-reviewed journals will be included in this review.

As mentioned earlier, we will conduct 2 searches that will be limited to children and adolescents younger than 18 years of age. The first search will include the following variations of AAP: “atypical antipsychotics,” “atypical neuroleptics,” “second-generation antipsychotics,” “second-generation neuroleptics,” “antipsychotics,” and “neuroleptics” for AAP [34].

We determined the following inclusion and exclusion criteria based on a literature review and the objectives of this study. All medication trials published in English pertaining to AAP in subjects younger than 18 years of age that reported NAFLD as an outcome, assessed by radiological methods (including liver ultrasound) or liver biopsy, will be included in this review. Moreover, prospective and retrospective observational studies of children and adolescents on AAP with reported NAFLD indicators will be included. Finally, case series and reports of NAFLD in children and adolescents on AAPs will be included. We will exclude conference abstracts, editorials, letters to editors, treatment guidelines, and studies published as abstracts only. Reviews (systematic and nonsystematic) will be excluded; however, the bibliographies of relevant papers will be reviewed. We will exclude studies in which AAP were used as an add-on or in combination with other medications (such as antiepileptics, first-generation antipsychotics, and selective serotonin uptake inhibitors), and medications that are a combination of AAP and selective serotonin uptake inhibitors including Fluoxetine; however, we will include studies where AAP constitute 1 arm of the study [35]. Due to the overlap of NAFLD risk factors with other comorbidities and varying nutritional backgrounds, we will also exclude studies examining patients with pre-existing medical conditions including eating disorders [17,18]. Our search will be limited to studies published in English, and nonhuman studies will be excluded. The review and comparison of results will be conducted using Endnote.

The primary outcome of the present study is NAFLD in children and adolescents, as assessed by either liver biopsy or using a radiological tool including hepatic US, MRI, MRS, and transient elastography among children and adolescents on AAP. Despite the relationship between NAFLD and metabolic syndrome, we did not include variables of metabolic syndrome in our outcomes because it is not the focus of our review and it has been previously studied, including in a recent meta-analysis [36]. Secondary outcomes will include changes in liver enzymes.

Investigators RH, FAN, GAA, and MA will independently review the titles and abstracts of the retrieved studies and exclude duplicates and irrelevant studies based on the aforementioned eligibility criteria. All the potentially eligible abstracts will be further assessed for eligibility by thoroughly reviewing their full texts. Results will be compared, and discrepancies will be resolved by consensus and by consulting investigators AA, CT, and ELA when needed. The Cohen κ will be calculated as a measure of interrater agreement. All studies that meet the eligibility criteria will be included in our analyses. Data extraction will be carried out using a standard form.

The quality of the studies will be assessed using the STROBE (Strengthening the Reporting of Observational studies in Epidemiology) guidelines [37] for cohort, case-control, and cross-sectional studies and the Newcastle-Ottawa Scale for nonrandomized studies. The quality of randomized controlled trials will be evaluated using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) method.

If the results allow for conducting a meta-analysis, we will report the outcomes by calculating the weighted pooled estimate of changes in the outcomes [38]. The risk of bias will be evaluated using three types of homogeneity tests: (1) forest plot, (2) Cochrane Q test (chi-square test), and (3) Higgins I2 statistics. In the forest plot, greater overlap between the CIs indicates greater homogeneity.

Studies have suggested that the pediatric population on AAP is more at risk of developing long-term adverse effects due to AAP, including weight gain, hyperlipidemia, and insulin resistance [14]. Therefore, we have grounds to speculate that children on AAP may be at a greater risk of developing disorders associated with metabolic syndrome, including NAFLD. This research project is specifically important due to the current trends in overprescribing AAP in children aged below 18 years [39].

Due to the dearth of systematic reviews on this vital topic, the need for understanding the possible association between AAP and NAFLD in this population across the literature landscape is warranted. Conducting this systematic review would serve as a comprehensive foundation for future studies and help devise interventions for the child and adolescent population.

The PRISMA flowchart was chosen to present the results of this study. There is a global rise in the use of AAP in treating children and adolescents below the age of 18 [39], which can cause long-term adverse effects and metabolic complications. We hope this research project will serve as a foundation for future studies and assist in devising interventions and reforming clinical guidelines of AAP use for improved patient safety.