Background and aims To investigate the pharmacotherapeutic pattern of patients with lupus nephritis in China and its impact on the hospitalisation cost.

Methods Data were identified by the primary diagnosis of lupus nephritis from the electronic medical record system for retrospective analysis. All treatment drugs were divided into rheumatic drugs and non-rheumatic drugs for study. The hospitalisation expenses, drug utilisation rate, and its impact on the total cost were analysed.

Results 305 patients with LN between January 2014 and December 2015 were included in this study. The average hospitalisation cost was $2109.26, including medical service fees, nursing fees, diagnosis fees, etc. Among them, drug cost was accounted for the high proportion ($1041.41, 49.37%), of which the non-rheumatic drugs were accounted for the major proportion ($892.16,87.70%). In non-rheumatic drugs, alimentary system drug had the high utilisation rate ($147.74, 95.03%); antimicrobial drugs had the most per person cost ($581.76, 55.30%). According to the result of principal component analysis, the first principal component, which contains antimicrobial drugs and the alimentary system drugs, accounted for 77.3% cumulative variance contribution rate. Therefore, the cost of the first principal component had a great impact on the total cost. Based on result of the association analysis, the prescription of $1 GCs would produce $2.76alimentary system drugs and $2.76 anti-osteoporosis drugs to prevent adverse reactions of GCs.

Conclusions Decrease in the cost of antibiotics and alimentary system drugs could significantly reduce the patient‘s hospitalisation expenses. To save the disease burden, the cost of drugs for the prevention of GC adverse reactions also should be properly managed.