Prolonged cough in children refers to a persistent cough lasting for more than three to four weeks that is not associated with a known underlying respiratory disease, such as cystic fibrosis or asthma (1,2). Prolonged or chronic cough causes distress to parents, and affects the quality of life of parents and children (3,4); while cough may be seen as a common condition of childhood without serious consequences, ignoring a cough that may be the sole presenting symptom of an underlying respiratory illness can lead to delayed diagnosis and progression of a serious illness or chronic respiratory morbidity, such as bronchiectasis (5,6). It is, therefore, important that a thorough diagnostic approach be taken.
The etiology of prolonged cough in children is well-recognized as being different to that of adults, and the management of prolonged cough in children must, therefore, differ from the recommended management for adults (7,8). The most common causes of adult cough include asthma, gastroesophageal reflux or upper airway cough syndrome (previously known as postnasal drip) (9); however, current evidence suggests that these causes are not common in children with prolonged cough (7,8,10,11). Underlying abnormalities, such as airway lesions, have been found to be prevalent in younger (preschool-aged) children (2); therefore, the identification of potential causes must be considered along with treatment for the cough.
Previous guidelines have been published by American (1,12), British (13) and European (14) respiratory groups regarding the management of cough. However, some of these guidelines do not specifically address the role of antibiotic therapy in the management of prolonged cough for children. A recent ‘umbrella’ review of the Cochrane library highlighted the lack of evidence available on the management of prolonged cough in children (7).
Prolonged cough can be classified into two types – specific and nonspecific. Specific prolonged cough refers to the presence of signs and symptoms (such as the presence of a ‘moist’ or ‘productive’ cough) that increases the likelihood of an underlying disorder being the cause of the cough. Nonspecific cough, known as a ‘dry’ cough, has minimal or nonexistent secretions and a lack of other signs and symptoms (7,15).
To determine the role of antibiotic treatment for prolonged cough in children, a thorough search of three major databases (PubMed, MEDLINE and the Cochrane library) was performed. The search terms were ‘cough’ and ‘anti-bacterial agents’ (MeSH subject headings), and the search was limited to paediatric populations, randomized controlled trials (RCTs), and reviews or meta-analyses of RCTs. One review (16) investigating antibiotics for chronic moist cough was published in the Cochrane library in 2005. Since this review, there have been no further published RCTs investigating the treatment of prolonged cough with antibiotics.
This Cochrane review (16) concluded that antibiotics can be effective in resolving moist (prolonged) cough in children, but only in some situations. Two studies were included in the review (Darelid et al [17], and Gottfarb and Brauner [18]), both of which investigated the role of an antibacterial agent (amoxicillin-clavulanic acid [17] or erythromycin [18]) versus placebo in the treatment of young children (zero to six years of age) with a prolonged cough associated with Moraxella catarrhalis. The study setting for both of these reports was in paediatric outpatient clinics. It is likely that the population of children referred for paediatrician input differs from those presenting to general practitioner care.
The review (16) was limited by the small number of studies (only two) suitable for inclusion, and the poor study quality in both. Neither of the studies (17,18) scored highly on the Jadad quality scale (16,19). Both studies used a timeframe of greater than 10 days duration to define the cough as chronic, whereas in the current paediatric literature, this would be classified as subacute cough (20); both studies also included only preschool-aged children. In spite of these limitations, the review found that antibiotics can be effective treatment in younger children with a prolonged moist cough. The number needed to treat for clinical cure was three (for every three children treated, one will be cured), and the number needed to treat to avoid progression of the illness was four (16).
Due to the small number of results, the database search was repeated, removing the previous limits of RCTs and reviews or meta-analyses of RCTs. A retrospective observational study (21) was found involving children with an established diagnosis of protracted bacterial bronchitis, which has been previously identified as a common cause of prolonged cough in children (2,10). This may explain the findings of the previously mentioned Cochrane review (16) that antibiotics sometimes can be beneficial for prolonged moist cough in children.
This observational study (21) found that although there has appropriately been emphasis in the past decade on reducing the prescription of antibiotics for upper respiratory tract infections in children, not enough attention has been paid to those children who may benefit from antibiotic therapy. The authors have suggested that antibiotic therapy should be seriously considered if a wet cough continues for more than three to four weeks. This is in accordance with the current American Pediatric URI Consensus Team statement that “antimicrobial treatment for prolonged cough (longer than 10 days) may be indicated occasionally” (22). It should be noted that a large proportion of the included patients in this study were very young (59% were younger than two years of age at onset of symptoms), and that symptoms had been present for more than one year in many (59%) of the participants (21). The setting for this study was in a specialist paediatric respiratory unit.
While a small number of studies were found that examined the role of antibiotics for moist (specific) prolonged cough, a deficit of evidence exists regarding the treatment of a prolonged dry (nonspecific) cough in children. One evidence-based review (23) was found examining the management of chronic nonspecific cough in childhood. This review found that there was no evidence to support the use of antibiotics in children with prolonged nonspecific cough. It has been widely recognized that in most cases, this type of cough is not serious and will self-resolve without intervention (7,23). Attention to parental concerns and fears must be part of the treatment process (7). The rarity of a serious cause combined with the knowledge of no large efficacy to treatment can alone be supportive and reassuring.