CRP and chronic kidney disease: Subgroup analysis based on the study country showed that in studies conducted in the USA, contrary to studies conducted in other countries, oral paricalcitol supplementation was able to reduce significantly CRP levels in CKD patients (studies conducted in the USA: WMD= -4.34; 95% CI= )-5.43, -3.25(; P = < 0.001; studies conducted in other countries: WMD = 0.35; 95% CI= (-2.01, 2.72); P = 0.77).