What is the evaluation for pulmonary tuberculosis (PTB) using X-ray in the Philippines?

From the Guidelines

I strongly recommend using chest radiography as the initial test for evaluating pulmonary tuberculosis (PTB) in the Philippines, as it has high sensitivity for detecting manifestations of active TB 1. The Philippines has a high TB burden, and any suspicious X-ray findings should be followed up with sputum testing for acid-fast bacilli (AFB) and GeneXpert MTB/RIF testing to confirm the diagnosis and check for drug resistance. Some key points to consider when evaluating PTB using X-ray include:

• Chest radiography has high sensitivity but relatively poor specificity due to the overlap of findings with nontuberculous pulmonary infection 1
• The yield of chest radiography in high-risk patients ranges from 1% to 7%, although it is not clear how many of these cases would have been suspected on the basis of clinical symptoms alone 1
• Lobar pneumonia with associated hilar and/or mediastinal adenopathy or cavitary air space disease involving the apical posterior segments of the upper lobe or superior segment of the lower lobe should raise particular concern 1
• When chest radiography confirms the clinical suspicion of active TB, it is sufficient to warrant respiratory isolation pending sputum cultures 1
• In patients who are immunocompromised, particularly those with AIDS and very low CD4 counts, chest radiographs may be deceptively normal 1
• CT may be used when tuberculosis is suspected and radiography is nonrevealing or nondiagnostic, as it can increase the specificity of the diagnosis of TB and show distinct findings such as cavitation or endobronchial spread with tree-in-bud nodules 1. If diagnosed with drug-sensitive PTB, the standard first-line treatment is a 6-month regimen consisting of 2 months of isoniazid, rifampicin, pyrazinamide, and ethambutol (intensive phase), followed by 4 months of isoniazid and rifampicin (continuation phase). Treatment should be administered under Directly Observed Treatment, Short-course (DOTS) through the National TB Program, available at public health centers throughout the Philippines at minimal or no cost. Patients should be monitored for medication side effects, including liver toxicity and vision changes. TB is highly contagious through airborne transmission, so household contacts, especially children under 5 years old, should be screened for TB and possibly given preventive therapy. Proper nutrition, adequate rest, and avoiding alcohol during treatment are important for recovery. Early diagnosis and complete treatment adherence are crucial to prevent drug resistance and achieve cure.

From the Research

Evaluation of Pulmonary Tuberculosis using X-ray in the Philippines

• The evaluation of pulmonary tuberculosis (PTB) using X-ray in the Philippines has been studied in various research papers 2, 3.
• A study published in 2019 found that automated chest X-ray reading for tuberculosis in the Philippines can improve case detection, with a sensitivity of 0.98 and a specificity of 0.69 2.
• Another study published in 2012 found that the Tuberculosis Diagnostic Committees (TBDCs) in Manila and Quezon Cities contribute to the National TB Program by ensuring the judicious use of resources, with 53% of patients in Manila City and 65% in Quezon City being classified as active TB patients 3.
• A more recent study published in 2024 found that multiple automated chest X-ray algorithms can achieve or exceed the minimum target accuracy for a TB triage test, with improvement when using setting- or population-specific thresholds 4.

Diagnostic Accuracy of X-ray for PTB

• The diagnostic accuracy of X-ray for PTB has been found to be high, with a study published in 2020 finding that high-resolution computed tomography (HRCT) has a diagnostic accuracy of 84.26% for PTB 5.
• Another study published in 2019 found that the area under the receiver operating characteristic curve for software readings of chest X-ray was 0.93, with a sensitivity of 0.98 and a specificity of 0.69 2.

Limitations and Challenges

• The use of X-ray for PTB diagnosis has some limitations and challenges, including the need for further research to assess the contributions of TBDCs in reducing diagnostic and treatment delays, and factors affecting the sustainability of the TBDCs 3.
• Additionally, the cost and practicality of using X-ray for PTB diagnosis in resource-limited settings can be a challenge, with a study published in 1998 finding that X-ray photofluorography is relatively expensive and impractical for use in isolated areas 6.