Provided herein are methods, assays and devices for the differential diagnosis and detection of disease progression of autoimmune diseases. The methods, assays and devices provided herein produce and analyze binding patterns of peripheral-blood antibodies on mimetic peptide arrays that differentiate autoimmune diseases, and identify patients progressing to internal organ complications such as interstitial lung disease (ILD), and gastric antral vascular ectasia (GAVE), or renal involvement.