Quality assessment and data extraction
Two authors (Jixiang Deng and Yuting Chen) independently screened the manuscripts and extracted data. The Newcastle-Ottawa quality assessment scale (NOS) was performed to assess the methodological quality. The relevant data were extracted from the included studies: first author’s name, publication year, study type, study population, sample size, gender, age, body mass index (BMI) and detection methods of resistin levels. Additional, we e-mailed the corresponding author to obtain available information.