GSTM1 and juvenile idiopathic arthritis: N: number; JIA: juvenile idiopathic arthritis; yr: years; BMI: body mass index; BMI SDS: BMI standard deviation score; ANA: antinuclear antibody; RF: rheumatoid factor; HLA- B27: Human Leukocyte antigen-B27; ESR: erythrocyte sedimentation rate; CRP: C reactive protein; Hb: hemoglobin; PLT: platelets; WBC: white blood count; CAR: C reactive protein to albumin ratio; PLR: platelet to lymphocyte ratio; NLR: neutrophil to lymphocyte ratio; MTX: methotrexate; NSAIDs: non steroid anti-inflammatory drugs