Healthy Late-preterm infants born 33-36+6 weeks gestational age have higher risk for respiratory syncytial virus hospitalization.

BACKGROUND: Respiratory syncytial virus (RSV) is a leading cause of hospitalization for children <1year old and is more severe in premature infants. OBJECTIVE: To assess whether late preterm (LPT) birth is an independent risk factor for RSV hospitalization and more severe RSV disease in children less than 24months old. METHODS: We conducted a retrospective cohort study of children enrolled in the military health system. LPT birth was defined as 33+0 through 36+6weeks gestation. Patients who received palivizumab or had known risk factors for RSV were excluded. Adjusted hazard ratios (HR) for LPT birth were calculated using a Cox proportional hazard model, while controlling for sex and RSV season. Severity of illness was assessed by comparing the need for respiratory support, length of stay, and age at RSV hospitalization between LPT and term children. RESULTS: A total of 599,535 children for 1,216,382 person-years were studied, of which 7597 children were admitted for RSV infection. LPT infants accounted for 643 (8.5%) of these RSV hospitalizations. The incidence density for RSV hospitalization of LPT infants was higher than term children (12.1 vs 7.8 per 1000 person-years). LPT infants had an increased adjusted risk for RSV hospitalization; specifically, those born 33+0 through 34+6weeks (HR 2.45; 95% confidence interval (CI) 1.96-3.07), and 35+0 through 36+6weeks (HR, 1.92; 95% CI, 1.66-2.22). LPT infants had longer hospital stays and required more respiratory support than term children. CONCLUSIONS: LPT birth is an independent risk factor for severe RSV disease and need for hospitalization.

Azithromycin in early infancy and pyloric stenosis.

BACKGROUND AND OBJECTIVE: Use of oral erythromycin in infants is associated with infantile hypertrophic pyloric stenosis (IHPS). The risk with azithromycin remains unknown. We evaluated the association between exposure to oral azithromycin and erythromycin and subsequent development of IHPS. METHODS: A retrospective cohort study of children born between 2001 and 2012 was performed utilizing the military health system database. Infants prescribed either oral erythromycin or azithromycin as outpatients in the first 90 days of life were evaluated for development of IHPS. Specific diagnostic and procedural codes were used to identify cases of IHPS. RESULTS: A total of 2466 of 1 074 236 children in the study period developed IHPS. Azithromycin exposure in the first 14 days of life demonstrated an increased risk of IHPS (adjusted odds ratio [aOR], 8.26; 95% confidence interval [CI], 2.62-26.0); exposure between 15 and 42 days had an aOR of 2.98 (95% CI, 1.24-7.20). An association between erythromycin and IHPS was also confirmed. Exposure to erythromycin in the first 14 days of life had an aOR of 13.3 (95% CI, 6.80-25.9), and 15 to 42 days of life, aOR 4.10 (95% CI, 1.69-9.91). There was no association with either macrolide between 43 and 90 days of life. CONCLUSIONS: Ingestion of oral azithromycin and erythromycin places young infants at increased risk of developing IHPS. This association is strongest if the exposure occurred in the first 2 weeks of life, but persists although to a lesser degree in children between 2 and 6 weeks of age.

Children with Down syndrome are high-risk for severe respiratory syncytial virus disease.

OBJECTIVE: To assess Down syndrome as an independent risk factor for respiratory syncytial virus (RSV) hospitalization in children younger than 3 years of age and to evaluate illness severity. STUDY DESIGN: A retrospective cohort study of children enrolled in the military health system database was conducted. The effect of Down syndrome on RSV hospitalization was assessed by Cox proportional hazards model, while we controlled for risk factors. Disease severity was assessed by length of hospital stay, need for respiratory support, and age at hospitalization. RESULTS: The study included 633 200 children and 3 209 378 person-years. Children with Down syndrome had a hospitalization rate of 9.6% vs 2.8% in children without Down syndrome. Down syndrome had a greater adjusted hazard ratio (HR) for RSV hospitalization than most risk factors, 3.46 (95% CI 2.75-4.37). A sensitivity analysis demonstrated HR 3.21 (95% CI 2.51-4.10) for patients with Down syndrome ages 0-23 months and HR 5.07 (95% CI 2.21-11.59) ages 24-36 months. The median (IQR) length of stay of children with and without Down syndrome was 4 days (2-7) and 2 days (1-4) (P < .001). Patients with Down syndrome had a greater risk of requiring respiratory support (relative risk 5.5; 95% CI, 2.5-12.3). The median (IQR) ages at admission for children with and without Down syndrome were 9.8 months (5.5-17.7) and 3.5 months (1.7-8.7) (P < .001). CONCLUSIONS: Down syndrome is independently associated with an increased risk for RSV hospitalization. Children with Down syndrome are older at time of RSV hospitalization and have more severe RSV illness than children without Down syndrome. This increased risk for hospitalization continues beyond 24 months.

The effect of rotavirus immunization on rotavirus gastroenteritis hospitalization rates in military dependents.

We conducted a retrospective review of all U.S. military dependents less than 5 years old hospitalized with rotavirus-associated gastroenteritis from July 2003 to June 2009. The two post-vaccine seasons showed a significant reduction of 62.4% (95% CI, 58.6-65.8, P<0.001) in rotavirus gastroenteritis hospitalization rate compared to the three pre-vaccine seasons. Infants less than 12 months old showed the greatest reduction in incidence at 75.3%. A substantial decrease was also seen in unvaccinated children as well. Vaccine efficacy against hospitalization was 86.0% (95% CI, 77.7-91.3) after just a single dose. The overwhelming majority of children hospitalized for rotavirus since the introduction of the vaccine (ranging from 91.8 to 100% per season) had not received any of the rotavirus vaccine series.