The volume ratio of ground glass opacity in early lung CT predicts mortality in acute paraquat poisoning

Abstract

Background: Pulmonary injury is the main cause of death in acute paraquat (PQ) poisoning. However, whether quantitative lung computed tomography (CT) can be useful in predicting the outcome of PQ poisoning remains unknown. We aimed to identify early findings of quantitative lung CT as predictors of outcome in acute PQ poisoning.

Methods: Lung CT scanning (64-slide) and quantitative CT lesions were prospectively measured for patients after PQ intoxication within 5 days. The study outcome was mortality during 90 days follow-up. Survival curves were derived by the Kaplan-Meier method, and mortality risk factors were analyzed by the forward stepwise Cox regression analysis.

Results: Of 97 patients, 41 (42.3%) died. Among the eight different types of lung CT findings which appeared in the first 5-day of PQ intoxication, four ones discriminated between survivors and non-survivors including ground glass opacity (GGO), consolidation, pneumomediastinum and "no obvious lesion". With a cutoff value of 10.8%, sensitivity of 85.4% and specificity of 89.3%, GGO volume ratio is better than adopted outcome indicators in predicting mortality, such as estimated amount of PQ ingestion, plasma or urine PQ concentration, acute physiology and chronic health evaluation (APACHE) II and sequential organ failure assessment (SOFA) scores. GGO volume ratios above 10.8% were associated with increased mortality (hazard ratio, 5.82; 95% confidence interval, 4.77-7.09; P < 0.001).

Conclusions: The volume ratio of GGO exceeding 10.8% is a novel, reliable and independent predictors of outcome in acute PQ poisoning.

Fig 1. Flow chart.

Fig 2. Eight CT findings of PQ poisoning captured within the first 5-day.

A. ground glass opacity (GGO); B. consolidation; C. pleural thickening; D. hydrothorax; E. fibrosis; F. pneumomediastinum; G. nodule; H. “no obvious lesion”. Arrows represented the lesions.

Fig 3. Kaplan-Meier survival curves of 97 paraquat poisoned cases stratified according to different CT findings within the first 5-day period.

Patients were categorized into two groups based on whether or not they presented the specific CT finding. The P values were derived by log-rank test.

Fig 4. The receiver operating characteristic (ROC) curves constructed for outcome prediction by amount of paraquat (PQ) ingestion, plasma and urine concentrations of PQ, scores of Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA), as well as volume ratio of Ground glass opacity and consolidation following PQ poisoning.

Fig 5. Kaplan-Meier survival curves of 97 paraquat poisoned cases stratified according to levels of GGO volume ratios within the first 5-day period.

Patients were categorized into three groups based on quartile levels of GGO volume ratios. Comparisons between curves showing difference with statistical significance (P < 0.05) are indicated.