Chest X ray score (Timika score): an useful adjunct to predict treatment outcome in tuberculosis

Chest X-ray (CXR) has been used since long as an aid in the diagnosis of pulmonary tuberculosis (PTB) and also to determine the extent of the disease. The present study was conducted to evaluate the correlation of disease extent on CXR basing on the Timika CXR score with clinical and microbiological parameters at baseline, in sputum positive cases of pulmonary tuberculosis.

The study was conducted at a tertiary referral centre for chest diseases in Bangalore, Karnataka from January 2017 to January 2018. This is a prospective study of new sputum smear positive pulmonary tuberculosis cases diagnosed in the department of Pulmonary Medicine. At baseline, patients' symptoms and signs on chest auscultation were recorded. The clinical scoring was done by the Karfosky performance score (KPS) and TB score I (Bandim TB score) and II. Baseline CXR- PA view of each patient was assessed independently by two chest physicians and evaluated by the Timika CXR scoring method. Routine blood investigations and sputum smear for acid fast bacilli were done. The correlation between the CXR score and other disease severity parameters was analysed.

Clinical scores such as the KPS and TB score I (Bandim TB score) and II, did not correlate with the presence of cavitary disease on CXR (p > 0.05). 48.6% of patients with cavitary disease had higher baseline AFB density in sputum (i.e. sputum smear microscopy grade 3+) as compared to 40% of patients with non cavitary disease, which was not statistically significant. CXR score > 71 was significantly associated with longer duration of symptoms, higher clinical scores (KPS and TB score I, II) and lower Body Mass Index (BMI) at diagnosis of PTB (p < 0.05). 65.2% of the patients with CXR score ≤ 71 had significantly higher baseline AFB density as compared to only 32.4% with CXR result > 71 (p 0.04). CXR score > 71 also had significant association with higher ESR.

Cavitary disease on CXR is associated with a higher mycobacterial load at baseline. The Timika CXR score is a simple, standard scoring system which can be used by a chest physician in a clinical setting. The CXR score significantly correlates with a broad range of clinical and microbiological measures of disease severity in PTB patients. Thus, it has a role in risk stratification, especially in patients not producing sputum or sputum negative PTB at diagnosis.