Platelet to Lymphocyte Ratio and Glucocorticoid Resistance in Newly Diagnosed Primary Immune Thrombocytopenia: A Retrospective Cohort Study.

BACKGROUND In China, evidence regarding to the association between platelet to lymphocyte ratio (PLR) and glucocorticoid (GC) resistance in participants with primary newly identified immune thrombocytopenia (ITP) is limited. We aimed to investigate whether PLR is independently linked with GC-resistant ITP. MATERIAL AND METHODS We non-selectively and consecutively collected 154 newly diagnosed ITPs. The start enrollment time and the end enrollment time were from March 2013 to June 2017. The independent and dependent variables were PLR measured at diagnosis and GC non-response. Other variables involved in the present work can be summarized as demographic data and factors that were correlated with PLR reported by published studies. Univariate and multivariate binary logistic regression model and sensitivity analysis were used to evaluate the associations between PLR and GC resistance. RESULTS After adjusting covariates, PLR level was negatively associated with GC non-response [odds ratio (OR)=0.89, 95% confidence intervals (CI): 0.80 to 0.98], and supported by propensity score matching model (OR=0.74, 95%CI: 0.57 to 0.96]. Nonlinearity of PLR and GC resistance was observed whose inflection point was 5.08 (by 2-piecewise model). The OR and 95%CI on both sides of inflection point were 3.14 (0.81 to 12.21) and 0.81 (0.69 to 0.95), respectively. Subgroup analysis showed no significant differences from subgroups. CONCLUSIONS Threshold effect on PLR and GC resistance is observed. When PLR is larger than 5.08, a unit increase of PLR is independently associated with 19% reduction of GC resistance.