Abstract: Seven trials consisting of 922 participants were included in this analysis. Trials ranged from 32 to 242 participants. On pooled analysis, corticosteroids reduced the subsequent occurrence of coronary artery abnormalities (odds ratio (OR) 0.29, 95% confidence interval (CI) 0.18 to 0.46; 907 participants; 7 studies; I² = 55%) without resultant serious adverse events (no events, 737 participants) and mortality (no events, 915 participants). In addition, corticosteroids reduced the duration of fever (mean difference (MD) −1.65 days, 95% CI −3.31 to 0.00; 210 participants; 2 studies; I² = 88%), time for laboratory parameters (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)) to normalise (MD −2.80 days, 95% CI −4.38 to −1.22; 178 participants; 1 study) and length of hospital stay (MD −1.41 days, 95% CI −2.36 to −0.46; 39 participants; 1 study). No studies detailed outcomes beyond 24 weeks. Subgroup analysis showed some potential groups that may benefit more than others; however, further randomised controlled trials are required before this can be the basis for clinical action. Evidence quality was graded according to the GRADE system. Evidence was considered high quality for the incidence of serious adverse events, mortality and time for laboratory parameters to normalise. Evidence was considered moderate for the incidence of coronary artery abnormalities due to potential inconsistencies in data geography and patient benefits according to grouping. Evidence was moderate for duration of clinical symptoms (fever, rash) due to potential subjectivity in measurement. Evidence was moderate for length of hospital stay as only one study recorded this outcome. This means that we are reasonably confident that the true effect is close to that estimated in this work. Moderate-quality evidence shows that use of steroids in the acute phase of KD can be associated with improved coronary artery abnormalities, shorter duration of hospital stay and a decreased duration of clinical symptoms. High-quality evidence shows reduced inflammatory marker levels. There were insufficient data available regarding incidence of adverse effects attributable to steroids, mortality and long-term (> 1 year) coronary morbidity. Certain groups, including those based in Asia, those with higher risk scores, and those receiving longer steroid treatment may have greater benefit from steroid use, especially with decreasing rates of heart problems, but more tests are needed to answer these questions. Evidence presented in this study suggests that treatment with a long course of steroids should be considered for all children diagnosed with KD until further studies are performed.

Plain-language summary: Evidence is current to November 2016. Male and female children diagnosed with Kawasaki disease were included in this review. We selected only randomised clinical trials. Trials compared the use of steroids against not using steroids. This review involves seven trials and 922 participants. Steroids appear to reduce the risk of heart problems after Kawasaki disease without causing any important side effects. They also reduce the length of symptoms (fever and rash), length of hospital stay, and blood markers associated with being unwell. Certain groups, including those based in Asia, those with higher risk scores, and those receiving longer steroid treatment, may have greater benefit from steroid use, especially with decreasing rates of heart problems, but more tests are needed to answer these questions. More tests are also needed to obtain a more accurate marker of the risk of serious side effects and to determine if there is a lower chance of death when using steroids. Evidence presented in this review suggests that treatment with a long course of steroids should be considered for all children diagnosed with Kawasaki disease until further studies are performed. Evidence quality was graded according to the GRADE system. Evidence was considered high quality for serious adverse events, mortality and time for laboratory parameters to normalise. Evidence was considered moderate quality for the risk of future heart problems, duration of clinical symptoms (fever, rash) and length of hospital stay. This means that we are reasonably confident that the true effect is close to that estimated in this work.