How Does Age at Onset Influence the Outcome of Autoimmune Diseases?

Table 1

Clinical differences between early and adult onset.

AD	Early onset	Late onset
SLE	Higher degree of morbidity [12]; Higher (SLEDAI) score at presentation; Higher incidence of renal disease; Malar rashes; Pericarditis; Hepatosplenomegaly; Hematologic alterations (Leucopenia); Higher use of prednisone; Additional immunosuppressive therapies; Greater lifetime of damages from the disease flares and the treatment side effects [13]; 2 times higher mortality rate; Growth failure; Delayed puberty; Fibromyalgia [11]; Higher odds of presenting proteinuria; Haemolytic anaemia; Arthritis [16]	Increased rate of pulmonary disease [11]; Increased rate of simultaneously developing another AD [12]
RA	Proximal Interphalangeal, metacarpophalangeal, elbow, metatarsophalangeal, and ankle joints; Classical rheumatoid hand deformities; Interstitial lung disease; Associated SS [18]; Shorter morning stiffness [19]	Acute onset in large and small joints (specially shoulders); PMR-like symptoms [20]; Constitutional features; Weight loss; Myalgia; Rheumatic nodules; Neuropathy [18]; Longer morning stiffness [19]	Positive RF PJIA*; Rapid onset of inflammation in multiple joints; Proximal interphalangeal, metacarpophalangeal, elbow, metatarsophalangeal, and ankle joints; Effects of the disease in a growing skeleton: Growth retardation; Accelerated growth of an affected joint [21]
SS	Recurrent parotid gland enlargement; Milder extraglandular manifestations [22]	Sicca symptoms [23]
T1D	Ketosis and ketoacidosis; Higher mean glycated hemoglobin [24, 25]	Better preserved B-cell function; Longer symptomatic period before diagnosis; Less frequency of insulin autoantibodies and HLA class II susceptibility alleles [25, 26]; Milder signs of metabolic decompensation and a lower glycated hemoglobin level at diagnosis [27, 28]
MS	Mainly relapsing remitting disease onset; Frequent presentation with brainstem-cerebellar dysfunction; Pyramidal symptom; Optic neuritis [29]	Primary progressive course; Motor symptoms are predominant
AITD	Often transient [10]; Delayed growth; Bradykinesia; Delayed pubertal development [30, 31]	Permanent [10]

AD: autoimmune disease; RA: rheumatoid arthritis; SS: Sjögren’s syndrome; T1D: type 1 diabetes; MS: multiple sclerosis; AITD: autoimmune thyroiditis; PJIA: polyarticular juvenile idiopathic arthritis; RF: rheumatoid factor.
*In RA, early age at onset is considered ≥16 years old. Positive RF PJIA is considered a comparable disease with a childhood onset (<16 years old).