Serum procalcitonin and C-reactive protein levels as diagnostic markers for distinguishing bacterial infections from lupus flares in systemic lupus erythematosus: A systematic review and meta‑analysis

To systematically evaluate the diagnostic performance of procalcitonin (PCT) and C-reactive protein (CRP) for distinguishing bacterial infections from lupus flares in systemic lupus erythematosus (SLE) via meta-analysis.Electronic databases were comprehensively searched. The pooled standard mean difference (SMD) and 95% confidence interval (CI) were calculated to estimate the differences of serum PCT and CRP levels between bacterial infections and flares in SLE. Sensitivity, specificity and summary receiver operating characteristics (SROC) curve were used to assess the diagnostic values of PCT and CRP. The use of fixed or random effects model depended on heterogeneity.Fifteen studies were included in the analysis. Serum PCT and CRP levels were significantly higher in SLE patients with bacterial infections compared to SLE patients with flares (PCT: SMD = 1.035, 95 %CI = 0.708 to 1.362; CRP: SMD = 1.000, 95 %CI = 0.758 to 1.242). The overall sensitivity, specificity, area under the SROC curve, positive likelihood ratios (PLR) and negative likelihood ratios (NLR) of PCT were 0.62, 0.88, 0.862, 6.63 and 0.36, respectively, while the same indicators for CRP were 0.72, 0.70, 0.784, 2.45 and 0.38, respectively.Serum PCT and CRP levels were significantly increased in SLE with bacterial infections. PCT had a better diagnostic performance than CRP. PCT had a high value of PLR and could serve as a rule-in marker, while CRP testing may result in a high false-positive rate due to low PLR; both markers had a suboptimal value of NLR and are not appropriate for ruling out bacterial infections.