Pulmonary hypertension during respiratory syncytial virus bronchiolitis: a risk factor for severity of illness.

BACKGROUND: Respiratory syncytial virus infection is the most frequent cause of acute lower respiratory tract disease in infants. A few reports have suggested that pulmonary hypertension is associated with increased severity of respiratory syncytial virus infection. We sought to determine the association between the pulmonary hypertension detected by echocardiography during respiratory syncytial virus bronchiolitis and clinical outcomes. METHODS: We retrospectively reviewed 154 children admitted with respiratory syncytial virus bronchiolitis who had an echocardiography performed during the admission. The association between pulmonary hypertension and clinical outcomes including mortality, intensive care unit (ICU) admission, prolonged ICU stay (>10 days), tracheal intubation, and need of high frequency oscillator ventilation was evaluated. RESULTS: Echocardiography detected pulmonary hypertension in 29 patients (18.7%). Pulmonary hypertension was observed more frequently in patients with congenital heart disease (CHD) (n = 11/33, 33%), chronic lung disease of infancy (n = 12/25, 48%), prematurity (<37 weeks gestational age, n = 17/59, 29%), and Down syndrome (n = 4/10, 40%). The presence of pulmonary hypertension was associated with morbidity (p < 0.001) and mortality (p = 0.02). However, in patients without these risk factors (n = 68), pulmonary hypertension was detected in five patients who presented with shock or poor perfusion. Chronic lung disease was associated with pulmonary hypertension (OR = 5.9, 95% CI 2.2-16.3, p = 0.0005). Multivariate logistic analysis demonstrated that pulmonary hypertension is associated with ICU admission (OR = 6.4, 95% CI 2.2-18.8, p = 0.0007), intubation (OR = 4.7, 95% CI 1.8-12.3, p = 0.002), high frequency oscillator ventilation (OR = 8.4, 95% CI 2.95-23.98, p < 0.0001), and prolonged ICU stay (OR = 4.9, 95% CI 2.0-11.7, p = 0.0004). CONCLUSIONS: Pulmonary hypertension detected by echocardiography during respiratory syncytial virus infection was associated with increased morbidity and mortality. Chronic lung disease was associated with pulmonary hypertension detected during respiratory syncytial virus bronchiolitis. Routine echocardiography is not warranted for previously healthy, haemodynamically stable patients with respiratory syncytial virus bronchiolitis.

Does consecutive influenza vaccination reduce protection against influenza: A systematic review and meta-analysis.

INTRODUCTION: Vaccination against influenza on an annual basis is widely recommended, yet recent studies suggest consecutive vaccination may reduce vaccine effectiveness (VE). PURPOSE: To assess whether when examining the entirety of existing data consecutive influenza vaccination reduces VE compared to current season influenza vaccination. DATA SOURCES: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to April 26, 2017; citations of included studies. STUDY SELECTION: Randomized, controlled trials (RCTs) and observational studies of children, adults and/or the elderly that reported laboratory-confirmed influenza infection over 2 or more consecutive influenza seasons were eligible. DATA EXTRACTION: Data related to study characteristics, participant demographics, cases of influenza infection by vaccination group and risk of bias assessment was extracted in duplicate. DATA SYNTHESIS: Five RCTs involving 11,987 participants did not show a significant reduction in VE when participants vaccinated in two consecutive seasons (VE 71%, 95% CI 62-78%) were compared to those vaccinated in the current season (VE 58%, 95% CI 48-66%) (odds ratio [OR] 0.88, 95% CI 0.62-1.26, p = 0.49, I2 = 39%). Twenty-eight observational studies involving 28,627 participants also did not show a reduction (VE for two consecutive seasons 41%, 95% CI 30-51% compared to VE for current season 47%, 95% CI 39-54%; OR 1.14, 95% CI 0.98-1.32, p = 0.09, I2 = 63%). Results from subgroup analyses by influenza type/subtype, vaccine type, age, vaccine match and co-morbidity support these findings; however, dose-response results were inconsistent. Certainty in the evidence was assessed to be very low due to unexplained heterogeneity and imprecision. LIMITATIONS: The inclusion of studies with relatively small sample sizes and low event rates contributed to the imprecision of summary VE and OR estimates, which were based on unadjusted data. CONCLUSION: Available evidence does not support a reduction in VE with consecutive influenza vaccination, but the possibility of reduced effectiveness cannot be ruled out due to very low certainty in this evidence. FUNDING SOURCE: CIHR Foundation Grant (PROSPERO: CRD42017059893).