Knee and ankle joint inflammation and walking difficulties in children and adolescents with juvenile idiopathic arthritis (JIA) tends to decrease and stabilize in the first five years after diagnosis, a study suggests.
But a significant number — about 1 in 4 — continue to show mild to moderate walking disability despite medication, supporting the need for non-medical approaches to help resolve or ease this problem.
The study, “Prevalence and course of lower limb disease activity and walking disability over the first 5 years of juvenile idiopathic arthritis: results from the childhood arthritis prospective study,” was published in Rheumatology Advances in Practice.
JIA, the most common rheumatic disease in children, primarily affects the lower limb joints, particularly those of the knee and ankle. This leads to slower walking speed and a shorter step length in children with JIA, which usually manifest as difficulties with basic activities like walking and stair climbing.
As walking is a key aspect of children and adolescent’s physical activity, “further research on the long-term impact of lower limb disease on walking ability in JIA is warranted,” researchers wrote.
Researchers in the U.K. investigated the prevalence and duration of lower limb disease activity and walking disability in JIA patients, up to age 16 at disease onset, over the first five years after diagnosis.
They analyzed medical records on 1,041 children (64% female, median age of 7.7 years at first visit) enrolled in the Childhood Arthritis Prospective Study (CAPS). Launched in 2001 in the U.K., CAPS was design to identify predictors of short-term and long-term outcomes of inflammatory arthritis.
Children were assessed at their first visit by a rheumatologist, who examined their joints and recorded the number of limited and active joints.
“A joint was considered active if there was swelling attributable to active synovitis [inflammation of the synovial (joint-lining) membrane] or, in the absence of swelling, limited motion accompanied by heat, pain or tenderness,” the researchers wrote. Limited joints were those with impaired motion.
Data on the number of active and limited joints at the study’s start (baseline) were available for 999 children, and at its five-year close for 576 children. A total of 204 had complete baseline and all subsequent follow-up information (with follow-ups done at six months, one year, and once each subsequent year).
Results showed the rates for knee and ankle joint synovitis (inflammation of the joint lining) and joint limitation of motion were high at the beginning of the study and stabilized at follow-ups, likely the result of therapy.
Specifically, researchers saw that at baseline inflammation of the knee and ankle affected 71% and 34% of these children, respectively, dropping to 8–20% and 6–12%, respectively, at the one-year follow-up. Hip and foot synovitis affected less than 11% of the patients at baseline, and fell to 1–3% at one year later.
The prevalence of limited knee and ankle joints followed the same trend, markedly decreasing from baseline to the first full-year evaluation. The prevalence estimates for joint inflammation was maintained after five years.
Researchers used the Childhood Health Assessment Questionnaire (CHAQ), a measure of functional disability (ranging from a score of 0, indicating less severe, to 3, meaning more severe), to measure walking disability.
Mild walking difficulties affected 52% of participants at the study’s start, dropping to 37% at six months and to 33% at one year, and stabilizing at 25–31% through subsequent follow-ups.
Moderate walking disability — meaning that patients have marked difficulties in walking or climbing steps — was more frequently observed at follow-ups relative to mild and severe walking disability, the study reported. At study start, 33% of the children showed moderate disability here, which fell to 25% at six months, 23% at one year and 17–23% thereafter.
Severe walking disability was relatively rare, detected only in 5% at baseline, and decreasing to below 1% after six months.
“These results suggest that prevalence rates for knee and ankle joint synovitis and joint limitation of motion are high at initial presentation and then stabilize with the initiation of medical therapies,” the researchers wrote.
However, “mild to moderate walking disability persisted in approximately 25% of patients for the duration of the study, despite a significant reduction in the frequency of lower limb synovitis,” they added, suggesting that “there is an unmet need for non-medical strategies designed to prevent and/or resolve persistent walking disability in JIA.”