Autoimmune connective tissue disease			Spondyloarthritis				Infectious arthritis		Crystal arthritis
Characteristic		Rheumatoid arthritis	Systemic lupus erythematosus	Vasculitis (including polymyalgia rheumatica, polyarteritis nodosa)	Ankylosing spondylitis	Psoriatic arthritis	Reactive arthritis	Inflammatory bowel disease arthritis	Bacterial	Viral	Gout	Calcium pyrophosphate deposition disease	Osteoarthritis
Symmetry
	Symmetric	+	+	+						+
	Asymmetric				++	++	+	+	+		+	+	+
Inflammatory		+	+	+	+	+	+	+	+	+	+	+
Noninflammatory													+
Number
	Pauciarticular				+	+	+	+	+		+	+	+
	Polyarticular	+	+	+						+
Joint involvement
	Spine-cervical/thoracic/lumbar	+			++	+	+	+	+				+
	Sacroiliac joint	+			++	++	+	+					+
Small joints
	Wrists	+	+	+					+	+		++	+
	Carpometacarpals												++
	Metacarpophalangeals	++	+							+		+
	Proximal interphalangeals	++	+	+		+				+
	Distal interphalangeals					++							++
	Ankle	+			++	++	++	+		+	+	+	+
	Metatarsophalangeals	+				++	+			+	++		+
Medium and large joints
	Shoulders	+	+		+	+	+	+				++	+
	Elbows	+	+		+	+	+	+	+
	Hips/knees	+		+	+	+	+	+	++			++	++
Systemic features		Fevers, uveitis, nodules, pneumonitis	Malar rash, oral ulcers, pleurisy	Rash, gangrene, stroke, headache, wrist drop, hemoptysis, gastrointestinal tract bleeding, proteinuria, hematuria	Uveitis, pneumonitis	Psoriasis, uveitis	Uveitis, urethritis, enteritis	Crohn disease, ulcerative colitis	Fever	Fever, rash	Tophi, uric acid stones	Preexisting osteoarthritis; Wilson disease, ochronosis, hemochromatosis
Laboratory tests		Rheumatoid factor, anti-cyclic citrullinated peptide	Antinuclear antibodies, double-stranded DNA, anti-Smith antibodies, urinalysis with proteinuria and hematuria, serum C3/C4	Erythrocyte sedimentation rate > 50, antineutrophil cytoplasmic antibody, temporal artery or other tissue biopsy, urinalysis with proteinuria and hematuria	Human leukocyte antigen B27		Testing for Chlamydia, Gonorrhea, Salmonella, and Shigella titers	Tissue biopsy	Lyme disease testing, joint/blood culture	Hepatitis B surface antigen, hepatitis C virus antibody, human immunodeficiency virus, human parvovirus B19	Serum uric acid, uric acid crystals in joint fluid	Calcium pyrophosphate crystals in joint fluid; measurements of thyroid-stimulating hormone, parathyroid hormone, iron, magnesium, or phosphorus
Radiographic findings		Erosions	No erosions	Pulmonary infiltrates/nodules, angiography: dilatation and stenosis	Sacroiliitis	Erosions, sacroiliitis			Effusions		Erosions, overhanging edges	Chondrocalcinosis	Osteophytes, joint space narrowing