Down syndrome (DS) is the most common chromosomal abnormality among live-born infants. It is associated with variable immunologic impairments. Few studies found an increased risk of case fatality due to sepsis in DS children compared with normal hosts hospitalized with sepsis.1,2 Another study found an increased risk for RSV infection in this population and raised the question of the need for RSV prophylaxis for these infants.3
The aim of this study was to evaluate the clinical characteristics of patients with DS admitted due to respiratory syncytial virus (RSV) infection.
The study was performed in Shaare Zedek Medical Center, a 550-bed university-affiliated general hospital. The pediatric department contains 40 beds, 3 of which are for intensive care patients. The annual pediatric admission rate ranged from 9249 to 11,137 per annum during the 8-year period of the study. The incidence of DS is very high in Jerusalem, due to the high proportion of ultra-orthodox Jewish and of Arab population. These groups share their grand multiparity with advanced age at delivery, the avoidance of prenatal screening programs, and the avoidance of termination of pregnancy even if DS is identified prenatally.4 Hence, our pediatric department has the unique opportunity to care for a high number of DS patients.
We reviewed the medical records of 222 children with DS, hospitalized in our medical center during a 9-year period (2000–2008). For all DS patients who were admitted due to RSV infection, we collected the following information: age, gender, admission diagnosis, length of hospital stay, mechanical ventilation, need for pediatric intensive care unit, associated conditions, and outcome.
These results were compared with those of a previously published study from our pediatric department, describing the clinical and epidemiologic characteristics of RSV in the general population over a 5-year period 2002–2007. All children with positive RSV antigen in a nasal swab were included in this study and the number of admissions ranged from 127 to 165 per year.5
During the study period, there were 41 hospitalizations for RSV infection in 39 children with DS. Of the DS patients, 27 (66%) were males. Mean age was 1.3 years (range, 0 to 6.1 years). Four children were younger than 2 months, 17 (41%) were older than 1 year and 8 children (20%) were older than 2 years. This age distribution is in contrast to the findings in a previous study in our medical center in which only up to 4% of healthy children with hospitalization due to RSV infection were older than 2 years.5 Mean duration of hospitalization was 10.9 ± 17 days, as compared with 4.9 ± 3 days in our cohort of healthy children (P = 0.0007).5 Twenty-one children (51%) had an underlying congenital cardiac disease; 5 additional patients were born prematurely. One girl was admitted due to RSV infection 3 times. Two children required mechanical ventilation and 1 of them died.
DS infants with underlying conditions (congenital heart disease, n = 21; age <2 month, n = 3; prematurity, n = 5) had longer hospitalization stay than those without any other risk factors (12 vs. 7 days), but these differences did not reach statistical significance (P = 0.23).
We found that children with DS are at a high risk for a severe course of RSV infection, as was shown by Bloemers et al.3
Several pathophysiologic mechanisms could underlie the high risk of RSV-infection-associated hospitalization seen among children with DS. DS is associated with immunologic impairments partially explained by abnormal thymus function and reduced number of B cells and T cells,7 decreased phagocytosis by neutrophils,8 low serum immunoglobulin levels,9 diminished lymphocyte numbers and responses to stimulations,10 and possibly zinc deficiency in some instances.6 All these could contribute to the predisposition to infections in this population, RSV included, to a longer and more complicated course of infection and to the occurrence of RSV infection beyond the first 2 years of life as found in this study.
Yet, our findings do not support the need for RSV prophylaxis in all infants born with DS, as Bloemers et al3 suggested to consider. First, DS patients admitted with RSV in our study were significantly older than healthy children with RSV infection, and thus RSV prophylaxis for 1 or even 2 years would have not significantly reduced hospitalizations in this special population. Second, many of these patients deserve RSV prophylaxis even without DS, due to congenital heart disease or prematurity. Thus, we believe that giving palivizumab to all children with DS would not significantly reduce the burden of hospitalizations in these children.
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