CRP and infection: Meta-analysis was conducted for factors reported in at least two studies, including two demographic factors (gender, age), two stone-related factors (stone size, stone number), six infection-related factors [history of UTI, positive urine culture, positive urine nitrite, leukocyte count, C-reactive protein (CRP), procalcitonin], two surgical factors (operation time, stent placement), and one comorbidity-related factor (diabetes mellitus).