Definitions for the level of evidence, strength of recommendation, and net benefit follow the "Major Recommendations."
- In areas where there is a high prevalence of tuberculosis (TB), chronic cough should be defined as it is in the World Health Organization Practical Approach to Lung Health (PAL) program as being 2 to 3 weeks in duration. Level of evidence, low; benefit, substantial; grade of recommendation, B
- In patients with chronic cough who live in areas with a high prevalence of TB, this diagnosis should be considered, but not to the exclusion of the more common etiologies. Sputum smears and cultures for acid fast bacilli and a chest radiograph should be obtained whenever possible. Level of evidence, low; benefit, substantial; grade of recommendation, B
- In patients with suspected TB, future investigations are needed to refine the criteria for suspecting TB and initiating a diagnostic evaluation, to utilize resources in a cost-effective manner and to improve patient and caregiver adherence to diagnostic recommendations. Level of evidence, expert opinion; benefit, substantial; grade of recommendation, E/A
- In populations at increased risk of becoming infected with TB and transmitting it to others by cough (e.g., those persons in prisons and nursing homes), special measures to prevent outbreaks must be made by public health agencies to screen for new cases, maintain surveillance of existing populations, and establish effective diagnostic and treatment programs early in the evaluation. Level of evidence, good; benefit, substantial; grade of recommendation, A
- In patients with unexplained chronic cough who have resided in areas of endemic infection with fungi or parasites, a diagnostic evaluation for these pathogens should be undertaken when more common causes of cough have been ruled out. Level of evidence, low; benefit, substantial; grade of recommendation, B
Definitions:
Quality of the Evidence
Good = evidence is based on good randomized controlled trials (RCTs) or meta-analyses
Fair = evidence is based on other controlled trials or RCTs with minor flaws
Low = evidence is based on nonrandomized, case-control, or other observational studies
Expert opinion = evidence is based on the consensus of the carefully selected panel of experts in the topic field. There are no studies that meet the criteria for inclusion in the literature review.
Strength of Recommendations
A = strong recommendation
B = moderate recommendation
C = weak recommendation
D = negative recommendation
I = no recommendation possible (inconclusive)
E/A = strong recommendation based on expert opinion only
E/B = moderate recommendation based on expert opinion only
E/C = weak recommendation based on expert opinion only
E/D = negative recommendation based on expert opinion only
Net Benefit
Substantial = There is evidence of benefit that clearly exceeds the minimum clinically significant benefit and evidence of little harm
Intermediate = Clear evidence of benefit but with some evidence of harms, with a net benefit between that defined for "substantial" and "small/weak"
Small/weak = There is evidence of a benefit that may not clearly exceed the minimum clinically significant benefit, or there is evidence of harms that substantially reduce (but do not eliminate) the benefit such that it may not clearly exceed the minimum clinically significant benefit
None = Evidence shows that either there is no benefit or the benefits equal the harms
Conflicting = Evidence is inconsistent with regard to benefits and/or harms such that the net benefit is uncertain
Negative = Expected harms exceed the expected benefits to the population
Table: Relationship of Strength of the Recommendations Scale to Quality of Evidence and Net Benefits
|
Net Benefit |
Quality of Evidence |
Substantial |
Intermediate |
Small/Weak |
None |
Conflicting |
Negative |
Good |
A |
A |
B |
D |
I |
D |
Fair |
A |
B |
C |
D |
I |
D |
Low |
B |
B |
C |
I |
I |
D |
Expert Opinion |
E/A |
E/B |
E/C |
I |
I |
E/D |