Search strategy: The PubMed, Embase, and Cochrane library databases were searched. All articles on the prevalence of hyperuricemia in adolescents published from Jan 1, 2000 to Dec 10, 2019 were searched comprehensively using the keywords “Adolescents”, “Adolescence”, “Teens”, “Teen”, “Teenagers”, “Teenager”, “Youth”, “Youths”, “Adolescents, Female”, “Adolescent, Female”, “Female Adolescent” or “Female Adolescents”, “Adolescents, Male” or “Adolescent, Male”, “Male Adolescent” or “Male Adolescents”, “Child”, “Children”, “Hyperuricemia”, “asymptomatic hyperuricemia”, “HUA”, “HU”, “uric acid”, “Prevalence”, “Incidence”, “Epidemiology”, “Prevalences” , and “Incidences”.
The following search strategy was used for Pubmed:
(“Adolescent”[Mesh] OR “Adolescents” OR “Adolescence” OR “Teens” OR “Teen” OR “Teenagers” OR “Teenager” OR “Youth” OR “Youths” OR “Adolescents, Female” OR “Adolescent, Female” OR “Female Adolescent” OR “Female Adolescents” OR “Adolescents, Male” OR “Adolescent, Male” OR “Male Adolescent” OR “Male Adolescents”) AND (((“Gout”[Mesh]) OR “Hyperuricemia”[Mesh]) OR “asymptomatic hyperuricemia” OR “HUA” OR “HU” OR “uric acid”) AND (((“Prevalence”[Mesh]) OR “Incidence”[Mesh]) OR “Epidemiology”[Mesh] OR “Prevalences” OR “Incidences”) AND ((“2000/01/01”[PDat] : “2019/12/10”[Pdat]) AND Humans[Mesh] AND English[lang])
Searches were restricted to English publications and human studies. In addition, we searched the reference lists of all identified relevant studies. Our meta-analysis was conducted fundamentally according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines (PRISMA).
Eligibility criteria: Papers were included if they met all of the following criteria: (1) all study participants were adolescents; (2) study data were general (i.e., population- rather than hospital-based); (3) original research; (4)cross-sectional studies ;(5) clearly stated study date; and (6) the most detailed study among duplicate studies of the same population (where applicable).
Studies were excluded if they (1) were not original research, such as a review or case report, (2) included participants with concomitant diseases or a history of taking medications known to affect uric acid metabolism, (3) were animal studies or (4) cohort studies, or (5) had a small sample size;(6) low Study quality.
Studies were imported into an EndNote X8 database and duplicates were removed. LHC and SGH screened the titles and abstracts of all studies against inclusion and exclusion criteria, respectively. The full text of potentially eligible studies were reviewed in duplicate by LHC and SGH against inclusion and exclusion criteria using a predesigned electronic assessment form. Discrepancies were resolved by discussion between the reviewers, with arbitration by a third reviewer (HBC) in case of disagreement.
Definitions of Hyperuricemia: The diagnostic criteria used for hyperuricemia for adolescents varied among the studies; we united the measurement unit of uric acid as mg/dL and listed the criteria in Table 1.
Data extraction: Two researchers (LHC, SGH) screened the literature independently and the screening results were cross-checked. According to the pre-designed data extraction table, the data were extracted independently, and the extraction results were cross-checked. The extracted data included the first author, study year, country, publication year, sample size, number of cases, and age of onset. We used the STROBE checklist to assess the quality of the research. Using this evaluation tool, we will evaluate six core components, including study design, participants, measurement, bias, descriptive data, and outcome data. Study quality was assessed independently by three reviewers (LHC, SGH, HBC). If two or three reviewers were in agreement, the study was included in the meta-analysis. If the score of the Study quality less than 4, we think it is low quality, and it will be eliminated in the final analysis. All data included in the study were tabulated.
Data analysis: The statistical analyses were performed using STATA software (ver. 15.0; StataCorp., College Station, TX, USA). First, a heterogeneity test was performed on the included studies. The heterogeneity statistic, I2, was classified as follows: 25%, low heterogeneity; 50%, high heterogeneity; and 75%, high heterogeneity. If the heterogeneity among the included studies was low (I2 ≤ 50%, P > 0.05), a fixed effect model was used; when there was high heterogeneity among the included studies (I2 > 50%, P < 0.05), a random effect model was adopted. Subgroup analyses were also performed according to gender, age, and region.