Understanding Complications of Systemic Juvenile Idiopathic Arthritis

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Parents can help monitor kids with systemic juvenile idiopathic arthritis (SJIA) for complications of this challenging disease.

In some children, SJIA goes into remission. SJIA symptoms may not come back at all or they may return in adolescence or later in life. Other children have ongoing inflammation that can sometimes lead to physical or systemic complications. At highest risk are kids whose symptoms aren't well controlled over time. 

Bone and Joint Damage

Advances in treatments that control inflammation have helped prevent many of the visible physical changes seen in children with SJIA just a few decades ago. Still, SJIA and its complications can take a toll. Persistent inflammation can slowly damage the joints, leading to reduced range of motion, loss of function, and sometimes the need for joint replacement early in life. SJIA, if not well controlled, is more likely than other types of juvenile arthritis to affect the jaw joint (the temporomandibular joint or TMJ), leading to a smaller-than-normal chin and changed appearance in some children. Fusion of the cervical spine (neck area) may also occur in kids with long-standing SJIA.

Long-standing inflammation of the joint lining can also interfere with normal growth and bone development, causing one arm or leg to be longer than the other and slowing or stunting overall growth. Corticosteroids used to treat SJIA can also prevent kids from growing normally. A decline in bone density begins within the first three months of corticosteroid use. Some studies have shown that taking small daily doses [2.5 milligrams–7.5 milligrams] of prednisone, a form of corticosteroid, or its equivalent may increase fracture risk. Continued use of corticosteroids can cause osteoporosis (a disease of the bones that causes them to be weak and brittle) or osteopenia (lower than normal bone mass not low enough to be classified as osteoporosis). Having either condition also may make kids more likely to experience fractures. Minimizing the use of corticosteroids can reduce these complications.

“Given that SJIA is chronic and unpredictable and patients are not always able to come off the steroids when we would like them to, it’s common practice to start calcium and vitamin D supplements [for bone protection] from the beginning,” says Daniel J. Lovell, MD, associate director of rheumatology and professor of pediatrics at Cincinnati Children's Hospital Medical Center.

Macrophage Activation Syndrome  

The most serious potential complication of SJIA is a condition called macrophage activation syndrome (MAS). Alexei Grom, MD, a pediatric rheumatologist at Cincinnati Children’s Hospital Medical Center and a leading authority on MAS, describes it as “a massive inflammatory response that overwhelms the whole body.”

MAS seems to start when the immune system isn't able to eliminate infected cells. The continuing presence of these cells stimulates the production of more and more white blood cells, leading to a flood of cytokines, or inflammatory proteins. The result is what Dr Grom calls a "cytokine storm."

Just what causes this in the first place isn't clear. There are a few known triggers, such as viral infections, changes in medication, and SJIA flares—a spike in disease activity.  Because MAS can quickly become serious, parents need to be alert to signs of the disease, says Daniel J. Lovell, MD, associate director of rheumatology at Cincinnati Children's Hospital Medical Center.

MAS can occur in any rheumatic disease, but for reasons that aren't clear, an estimated 80 percent of cases are associated with SJIA. Still, MAS isn’t common in kids with SJIA. A review of data has shown that only about 10 percent of children with SJIA develop MAS, but some develop it more than once.

Signs and symptoms of the disease may include a high, constant fever, headache, easy bruising or bleeding, seizures, changes in alertness and an enlarged liver. Because MAS can overwhelm the body very quickly—and can be fatal if not treated promptly—rapid diagnosis is crucial.

"Families should watch for any change in a child's level of alertness, any kind of listlessness, confusion or a loss of appetite. Those are also common signs of a viral infection, but if kids don't perk up, they look more lethargic than usual or they have seizures, then we need to be called immediately or they should go to the emergency department," Dr Lovell says.

Until recently, there was no standard checklist of signs and symptoms that could be used to make a firm diagnosis of MAS. Now, an international group of pediatric rheumatologists is developing them. Some of the important criteria include laboratory test results that show rapidly falling platelet counts, a low erythrocyte sedimentation rate, and extremely high ferritin levels.

“The key is to make the diagnosis early and start treatment quickly, before children develop full-blown MAS. Then treatment (with high-dose corticosteroids and sometimes strong immune suppressants) can be very effective. But if MAS is already affecting multiple organs and has a roaring start, then treatment is much more difficult,” Dr Lovell says.

Other Systemic Complications of SJIA

Some especially serious systemic complications associated with SJIA involve the lungs. In recent years, doctors have seen more cases of lung diseases, such as pulmonary artery hypertension and interstitial lung disease, in children with SJIA. Pulmonary artery hypertension is high blood pressure that affects the arteries in the lungs and the right side of the heart. In interstitial lung disease, lung tissue becomes scarred, making it harder to get oxygen into the bloodstream.

No one is quite sure why more children are developing these diseases. Parents should be alert for any signs of breathing problems, especially shortness of breath, and notify their pediatric rheumatologist as soon as possible.

Philip Kahn, MD, a pediatric rheumatologist and assistant professor of pediatrics at NYU Langone Medical Center in New York City, emphasizes the importance of treatment in regards to other systemic complications. He adds, “When the disease is undertreated, you can see hair loss, anorexia, anemia, large, swollen glands and malaise (a generalized feeling of discomfort and illness).”


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