Background: Whooping cough is an important cause of childhood morbidity and mortality. There are 20 to 40 million cases of whooping cough annually world-wide, 90% of which occur in developing countries, resulting in an estimated 200 to 300 000 fatalities each year. Much of the morbidity is due to the effects of the paroxysmal cough. Corticosteroids, salbutamol (beta 2 - adrenergic stimulant), and pertussis-specific immunoglobulin have been proposed as standard treatment for the cough. Antihistamines have also been administered. No systematic review of the effectiveness of any of these interventions or others has been performed.
Objectives: To assess the effectiveness and safety of interventions used to reduce the severity of the coughing paroxysms in whooping cough in children and adults.
Search strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (issue 2, 2003); MEDLINE (January 1966 to June 2003); EMBASE (1990 to June 2003) and LILACS (1982 to November 2001). We also scanned reference lists of identified trials and contacted authors of identified trials and relevant pharmaceutical companies.
Selection criteria: Randomised and quasi-randomised controlled trials of any intervention aimed at suppressing the cough in whooping cough; excluding antibiotics and vaccines.
Data collection and analysis: Two reviewers independently selected studies and extracted data. Our primary outcome was frequency of paroxysms of coughing. Secondary outcomes were frequency of vomiting, frequency of whoop, frequency of cyanosis, development of serious complications, mortality from any cause, side effects due to medication, admission to hospital and duration of hospital stay. Disagreements were resolved by discussion.
Main results: Nine studies satisfied the inclusion criteria but four had insufficient data for meta - analysis of pre-specified outcomes. Studies were small and poorly reported. The largest study had a sample size of 49 and the smallest study 18. All studies were performed in industrialised settings. Eligible studies assessed diphenhyramine, pertussis immunoglobulin, dexamethasone and salbutamol. No statistically significant benefit was found for any of the interventions. Diphenhydramine did not change coughing spells (mean increase of coughing spells per 24 hours 1.9 with 95%CI - 4.7 to 8.5) and pertussis immunoglobulin no change in hospital stay (0.7 days 95% CI -3.8 to 2.4), and a mean reduction of 3.1 whoops per 24 hours [95% CI -6.2; 0.02]. Dexamethasone did not show a clear decrease in hospital stay (-3.5 days 95% CI - 15.3 to 8.4) and salbutamol showed no change in coughing paroxysms per 24 hours [-0.22 95% CI - 4.13 to 3.69].
Reviewer's conclusions: Insufficient evidence exists to draw conclusions about the effects of any intervention for the cough in whooping cough.