37 for side effects
The numbers presented are from the best studies that are currently available. Some of these studies will NEVER be repeated and so this is all we'll ever have to go on. There will be continued study in some areas and we aim to incorporate this forward into our site. We're constantly monitoring the literature for updates (if you think there is something we've missed, email us!). The conclusions we draw are a best estimate, folks. We've presented what we think is the closest thing to the truth about this intervention, but our data is only as good as the studies that underlie it — and often, the studies aren't as complete or as good as we'd like. We present one number here for the NNT, but please realize this is an estimate and there is a range for what this intervention can offer a given person. That range will depend upon the person's spectrum of disease (mild/moderate/severe), their demographic, their subtype of disease, the setting of the intervention, their general health, and literally thousands of other variables. Using these numbers in practice means taking a number of large leaps about all of these variables, and also about the veracity of the underlying research. Therefore, as with any 'high quality' data, the application of data requires a doctor's expertise and deliberate consideration.
In Summary, for those who received the antibiotics:
- 100% saw no benefit
- 18% were helped by a reduction in symptoms, including cough
- 2.6% were harmed by medication side effects
In Other Words:
- None were helped (overall)
- 1 in 6 were helped (no cough at follow up)
- 1 in 37 were harmed (minor adverse effects at follow up)
Where We Get The Numbers:
Efficacy Endpoints: Clinical improvement or cure
Harm Endpoints: Reduction in cough
Narrative: Acute bronchitis is defined as a cough-related illness lasting 1-3 weeks with or without sputum in an individual without chronic lung disease and a normal chest radiograph.1 It is one of the most common conditions for which patients consult a physician and the most common reasons for seeking care are symptom severity, duration, and interference with daily activities.2 Less than 10% of cases are thought to be bacterial, few patients cite needing an antibiotic, and most guidelines do not recommend their routine use in bronchitis.1 4 But antibiotics, often broad spectrum,5 are prescribed for 60-80% of outpatient cases.3 This review examines the utility of antibiotics in improving symptoms and effecting clinical cure in adults with acute bronchitis.
Fifteen randomized controlled trials were included in this review. Antibiotics did not increase the number of subjects who were clinically improved or “cured” at follow up.* They did however decrease the percentage of patients with cough at a follow up visit (NNT=6). There was also a reduction in the duration of cough, days feeling ill, and days of limitations in daily activities, approximately one half of a day for each. Antibiotics slightly increased the number of patients with adverse effects (NNH=37)
Caveats: Acute bronchitis is defined as a cough-related illness lasting 1-3 weeks with or without sputum in an individual without chronic lung disease and a normal chest radiograph.1 It is one of the most common conditions for which patients consult a physician and the most common reasons for seeking care are symptom severity, duration, and interference with daily activities.2 Less than 10% of cases are thought to be bacterial, few patients cite needing an antibiotic, and most guidelines do not recommend their routine use in bronchitis.1 4 But antibiotics, often broad spectrum,5 are prescribed for 60-80% of outpatient cases.3 This review examines the utility of antibiotics in improving symptoms and effecting clinical cure in adults with acute bronchitis.
Fifteen randomized controlled trials were included in this review. Antibiotics did not increase the number of subjects who were clinically improved or “cured” at follow up.* They did however decrease the percentage of patients with cough at a follow up visit (NNT=6). There was also a reduction in the duration of cough, days feeling ill, and days of limitations in daily activities, approximately one half of a day for each. Antibiotics slightly increased the number of patients with adverse effects (NNH=37)
Figure 3 in the Cochrane review displays study data for this outcome measure. In its current form this forest plot suggests a small benefit in favor of antibiotics. However there are data entry errors for studies Stott 1976 and Verheij 1994, and the published meta-analysis for this outcome mistakenly employs a fixed effect rather than a random effects analysis, as the authors had intended (see p. 5 of the review for stated intentions regarding statistical analysis). These errors were confirmed with the Cochrane review lead author (personal communication January 5, 2012). When corrected this analysis and forest plot reveal no statistical benefit with antibiotics. Since these data are not available in the current Cochrane publication we have provided an amended figure 3 below:
Author: Koustav Mukherjee, MD
Published/Updated: January 30, 2012
