Fig. 4

Bland-Altman plots for creatinine for the comparison of A cVAMS sample and plasma concentrations; B blood and plasma concentrations; D vVAMS sample and blood concentrations; and F cVAMS and vVAMS sample concentrations. Boxplots of C creatinine B/P ratios per sampling time point. The boxes indicate the 25th and 75th percentile and median, and the flags show the minimum and maximum values. Single, double and quadruple asterisks (*, ** and ****) indicate significant differences from the median of t0 (Dunn’s multiple comparison test, α = 0.05). Passing-Bablok regression analysis for creatinine of E vVAMS sample concentrations plotted against blood concentrations; and G cVAMS sample concentrations plotted against vVAMS sample concentrations. VAMS volumetric absorptive microsampling, vVAMS venous VAMS, cVAMS capillary VAMS, CI confidence interval