Serious Complications Not Common in Uncomplicated Pertussis

From Medscape Medical News

Laurie Barclay, MD

August 4, 2011 — Infants with uncomplicated pertussis may have few serious complications, according to the results of a retrospective cohort study reported online July 28 in Hospital Pediatrics.
"Pertussis continues to be a serious illness in young infants with increasing incidence and high rates of hospitalization," write Sowdhamini S. Wallace, DO, Section of Pediatric Emergency Medicine, Department of Pediatrics at the Baylor College of Medicine in Houston, Texas, and colleagues.

"While young infants are more likely than older children to suffer from severe complications such as apnea, pneumonia, seizures, and encephalopathy, a spectrum of disease expression exists....The well-appearing infant with pertussis poses challenges to the emergency medicine physician as to which children would benefit from admission, and to the hospitalist physician as to the level of monitoring required for admitted patients."

The goal of the study was to identify risk factors that would predict complications among infants ages 0 to 6 months hospitalized during 2005 to 2009 for uncomplicated, confirmed pertussis, defined as lack of complications or lack of the need for initial intensive care admission.
Complications occurring during hospitalization included apnea, pneumonia, seizures, or encephalopathy.
Odds ratios (ORs) and 95% confidence intervals (CIs) for the association between each clinical variable (demographics, historical, laboratory, and imaging data) and the occurrence of complications were estimated with univariate analysis. Logistic regression was used for multivariable analysis.
Complications during hospitalization occurred in 46 (36.5%) of 126 participants, including 42 with apnea, of which 2 required endotracheal intubation; 7 with pneumonia; and 3 with seizures. There were no cases of encephalopathy and no deaths.

Factors predicting development of complications were age younger than 60 days (OR, 2.71; 95% CI, 1.08 - 6.82), cough duration of less than 7 days (OR, 5.38; 95% CI, 1.79 - 16.18), history of color change (OR, 5.24; 95% CI, 1.14 - 24.07), parental intervention (OR, 10.05; 95% CI, 1.67 - 60.39), and the need for supplemental oxygen in the emergency department (OR, 3.94; 95% CI, 1.37 - 11.36). At the time of complication, the median duration of cough was 9 days (range, 2 - 30 days). Initial complete blood cell count and radiographic findings did not predict complications.
"Infants with uncomplicated pertussis may be at low risk for developing respiratory failure or death," the study authors write. "Historical information may assist practitioners in determining risk for serious complications."
Limitations of this study include retrospective design, selection bias, classification bias, and potential confounding.
"Traditional screening via CBC [complete blood cell count] and chest radiography may not be useful to predict the risk of in-hospital complication in this uncomplicated population; however, younger age, shorter cough duration, parental report of color changes, and parental interventions or supplemental oxygen administration before hospital arrival may be associated with complicated hospital courses," the study authors conclude. "Prospective studies are needed to confirm these findings and develop a risk-stratification tool and evidence-based management guideline for these young infants."


Hosp Pediatr. Published online July 28, 2011.