Plasma proteomics in two Swedish cohorts with Ovarian Cancer

In the resulting data-file provided by the analysis platform, each individual protein measurement, assay and sample is labelled depending on passing or failing quality control as provided by the instrument software. Here, a total on 768 individual measurements (corresponding to 0.036%, 768/(404*5416)) did not pass quality control and were removed from further analyses. Two proteins (apolipoprotein E (APOE) and fibronektin 1 (FN1)) had detection rates below 95% across all samples and were removed from further analyses.

The resulting NPX values are on a log2 scale and in the logarithmic phase of the curve, one (1) increase of the NPX value corresponds to a doubling of the protein content. In the resulting data, a high NPX value corresponds to a high protein concentration. Each of the measured proteins has a lower limit of detection (LOD) given in the same NPX-scale which is determined at run time.

Here, measurements under LOD were kept as is in the downstream analysis. After quality control, the detection rate across all samples were 99.5 to 99.8%.