Quantifying the extent of TB lesions on chest X-ray

What is it about?

We analyzed chest X-rays performed at the initiation of treatment of 132 patients with susceptible TB and 102 patients with MDR-TB, using a validated score (Timika) and our proposed simplified score (SRS-TB). SRS-TB is based on dividing the surface of the chest X-ray in 6 section and allocating 1 point for the presence of any abnormality in each section. An extra point was added t the score for the presence of cavity anywhere, and a point for pleural effusion. The maximal possible score is 8. Timika score uses the same 6 section division and estimates as percentage the surface with abnormaltiies in each section. The percentage is multiplied by different coefficients for different type of lesions, finally divided by 600, and a 40 point coefficient is added in case of cavities. The results of the two scores in all patients were compared to each other and correlated with the type of TB (susceptible or MDR) and the treatment outcome (the result of treatment evaluated at 12 months). There was a good correspondence between the two scores in evaluating the severity of the lesion extension. There was a difference between the mean score for susceptible and MDR TB for both scores, with a more severe score in MDR. The correlation of treatment outcome didn't show a prognostic value for the radiologic scores, with good outcomes present in all group of scores (mild and severe). The worse outcome of treatment (death, relapse) were mostly met in patients with high radiology scores.

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Why is it important?

The use of a score to quantify the extension of abnormalities in TB patients could be used as a biomarker for prognosis of evolution. The scores are not powerful enough for predicting the suspicion of drug resistance at initial evaluation, but a higher score is associated with worse treatment outcome in all patients. Our study shows that using a simplified score can be as valuable as the use of a more complicated one.

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