Retrospective Multicenter Study of Respiratory Syncytial Virus Prophylaxis in Korean Children with Congenital Heart Diseases

Kim, Ah Young; Jung, Se Yong; Choi, Jae Young; Kim, Gi Beom; Kim, Young-Hwue; Shim, Woo Sup; Kang, I-Seok; Jung, Jo Won

The effectiveness of prophylactic palivizumab for prevention of RSV infection in CHD patients was shown by a randomized controlled study in 1998. 7) Palivizumab, a humanized monoclonal antibody against RSV, has been the gold standard for RSV prophylaxis in high risk groups, and recently was shown by a Cochrane metaanalysis to have significantly reduced the hospitalization rate of infected patients. 10) The study showed a 45% relative reduction in RSV hospitalization among high risk children receiving palivizumab (9.7% vs. 5.3%; p=0.003). before the palivizumab era, about more than 10% of all CHD infants required hospital admission for RSV infection and some needed intensive care; however, palivizumab vaccination at the start of RSV season has been proven to reduce the rate of hospitalizations by half (~5%). 7)12) 13) In Korea, according to the biweekly reports from the Korea Centers for Disease Control and Prevention, the seasonal outbreaks of RSV infection occur during the winter months, namely September through March. Almost all children are susceptible to RSV infection until they reach the age of 2 years, and on an average, nearly half will experience two episodes of infection. 2)9) Prior to the palivizumab era (from 2003 to 2006), in a study of 213 patients diagnosed with lower respiratory infection, 45 CHD patients (21.1%) were hospitalized due to RSV infection, 22 (48.9%) were treated in the ICU, 12 (26.7%) required mechanical ventilation, and 2 (4.4%) died; however, no deaths occurred among non-CHD patients. 14) In our study, the rate of mortality related to RSV infection (1.1%) was reduced significantly but was still a threat to infants with HS-CHD even after palivizumab injection, because the monoclonal antibody tends to attenuate but not eradicate RSV disease. 5)9) [15] [16] [17] Moreover, the rate of RSV-associated hospitalization of children <12 months old with HS-CHD who received more than one prophylactic injection was 12.5%, which was relatively higher than in previous reports from other countries (0.46% to 5.3%). 18) One- fourth of the patients were admitted to the ICU with RSV infection, and 3 patients were hospitalized for longer than 4 weeks. This could relate to incomplete vaccination, which would point to a lack of compliance with the guideline, as well as increased testing for RSV. 5)7)11) [19] [20] [21] [22] [23] Many cases started prophylaxis either earlier (n=70, 15%) or later (n=182, 39%) than the recommendation, and it can be argued that delays in identifying patients at risk could have affected the outcome. 23) Monthly injections of up to five injections are recommended once patients start treatment; however, the majority (69%) of patients in this study received less than four, including 36% who received only one injection. Therefore, factors involved in effective prophylactic treatment include ensuring that treatment is initiated at the right time, and that children with CHD are identified and followed up. Missing or delayed injections may lead to increased rates of re-hospitalization, making it essential to adhere to prophylactic guidelines. 24)25) According to many studies that have reported advantages in socio-economic aspects of prophylaxis of RSV infection in CHD patients under the age of 2 years, recommendations from the guidelines of Canada, Japan, Germany, and Austria for the use of palivizumab have included children younger than 24 months of age. 8) In contrast, the Korean guideline has recommend 12