From the Guidelines
The next step for a patient with chronic cough and a positive PPD test is to obtain a chest X-ray to rule out active tuberculosis. If the chest X-ray is normal, treatment for latent tuberculosis infection (LTBI) should be initiated. The standard regimen is isoniazid 300 mg daily for 6 to 9 months 1. Alternative regimens include rifampin 600 mg daily for 4 months or isoniazid plus rifapentine weekly for 3 months 1. If the chest X-ray shows abnormalities suggestive of active TB, further evaluation with sputum smear and culture for acid-fast bacilli is necessary before starting treatment. It's essential to consider that the chronic cough may or may not be related to TB, and other causes should be investigated if symptoms persist after appropriate TB management.
Some key points to consider in the management of chronic cough include:
- The most common causes of chronic cough are upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD) 1
- A thorough medical history and physical examination are crucial in determining the cause of chronic cough 1
- Empiric treatment trials may be necessary to diagnose and treat chronic cough, especially if the cause is not immediately apparent 1
- Regular follow-ups are crucial to ensure adherence and monitor for adverse effects during treatment 1
During treatment, it's crucial to monitor for side effects such as hepatotoxicity, especially in older adults or those with liver disease 1. Regular follow-ups are essential to ensure adherence and monitor for adverse effects. The patient's quality of life and potential morbidity and mortality associated with untreated TB or mismanaged chronic cough should be considered when making treatment decisions.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Next Steps for a Patient with a Chronic Cough and a Positive PPD Test
- The patient should undergo a clinical evaluation and chest x-ray to exclude the possibility of active tuberculosis (TB) 2
- If the patient has radiographic evidence of old (healed) TB infection, sputum testing should also be performed 2
- Treatment with isoniazid (INH) monotherapy (300 mg/d) is recommended to reduce the progression of latent tuberculosis to active disease 2
- The optimal treatment length for INH monotherapy is 9 months 2
- A 3-month course of combined rifampin (600 mg/d) and INH (300 mg/d) is equivalent in efficacy to INH monotherapy, but this regimen is not included in Centers for Disease Control and Prevention recommendations 2
Evaluation of Chronic Cough
- The initial assessment of chronic cough should include a detailed history, physical examination, chest radiograph, spirometry, exhaled nitric oxide, blood eosinophil count, and measurement of cough severity and quality of life 3, 4
- The top diagnoses to consider are asthma, chronic obstructive pulmonary disease, nonasthmatic eosinophilic bronchitis, gastroesophageal reflux disease, and upper airway cough syndrome 3, 5
- Additional studies are only obtained when red flags are present or the patient fails to respond after avoidance of high-risk factors and empiric treatment for the most likely respiratory and gastrointestinal diseases 3, 4
Management of Chronic Cough
- Empiric treatment should be initiated based on the most likely diagnosis 3, 5
- If diagnostic tests and/or specific directed treatments fail to control chronic cough, low-dose morphine, gabapentin, pregabalin, and/or cough control therapy are recommended 3, 5
- Referral to a pulmonologist or otolaryngologist may be warranted for patients with refractory chronic cough 5, 4