ABSTRACT
Objective:To explore the risk factors of hemothorax after rib fracture and evaluate its predictive value for hemothorax.Methods:A retrospective case control study was made on the data of 449 patients with rib fracture admitted to Jiangsu Shengze Hospital affiliated to Nanjing Medical University from January 2018 to November 2019. There were 308 males and 141 females，with the age range of 19-97 years［（57.4±14.0）years］. The hemothorax was defined as pleural effusion on chest CT or X examination on admission or within one week after admission. There were 330 patients in hemothorax group and 119 patients in non-hemothorax group. Indices were compared between the two groups，including gender，age，occupation，weight，height，underlying diseases［diabetes，chronic obstructive pulmonary disease（COPD），hypertension，hyperlipidemia］，causes of injury，imaging findings［number of rib fracture，flail chest，bilateral rib fractures，locations of rib fracture and intramural injuries（pneumothorax，pulmonary contusion，mediastinal emphysema and myocardial contusion）］，thoracic cavity drainage，injury to admission time，vital signs（blood pressure and heart rate），routine blood［white blood cell，hemoglobin（Hb），platelet，hematocrit（Hct）］，blood type，urine routine（urinary occult blood，urinary protein，urinary ketone body），biochemical examination［total cholesterol（TCHO），triglyceride（TG），high density lipoprotein（HDL-C），low-density lipoprotein（LDL-C），albumin（ALB），total bilirubin（TBIL），glutamic oxalacetic transaminase（AST），alanine transaminase（ALT），urea nitrogen（BUN），creatinine（CRE），glycosylated hemoglobin（HbA1C）］，coagulation tests［prothrombin time（PT），fibrinogen（FIB），plasma D-dimer（D-D），thrombin time（TT）］after admission，trauma score［chest wall injury score（CIS），injury severity score（ISS），new injury severity score（NISS）］and length of hospital stay. The univariate analysis was used to observe the correlation between each factor and hemothorax after rib fracture and to screen the significant correlation factors，followed by multivariate logistic regression analysis to further identify the independent risk factors. The receiver operating characteristic（ROC）curve was used to analyze the predictive value of continuous variables in independent risk factors and to calcuate the optimal threshold.Results:The two groups showed no significant differences in gender，occupation，weight，height，diabetes，COPD，hyperlipidemia，injury to admission time，blood pressure，heart rate，platelet，urine protein，urine ketone body，TCHO，HDL-C，TBIL，ALT，CRE，HbA1C or PT（ P>0.05）. The hemothorax group showed significantly decreased Hb，Hct，TG，LDL-C and TT and significantly increased age，number of rib fracture，white blood cell count，AST，FIB，D-D，trauma score（CIS，ISS，NISS）and length of hospital stay when compared to non-hemothorax group（ P<0.05）. There were significant differences in hypertension，causes of injury，flail chest，bilateral rib fractures and locations of rib fracture and urinary occult blood between the two groups（ P<0.05）. The univariate analysis showed that age，hypertension，number of rib fractures，flail chest，bilateral rib fractures，locations of rib fracture（upper chest anterolateral segment，middle chest anterolateral segment，middle chest posterolateral segment，middle chest proximal spinal segment，lower chest posterolateral segment，lower chest proximal spinal segment），pneumothorax，pulmonary contusion，myocardial contusion，thoracic cavity drainage，white blood cell count，urinary occult blood，BUN，FIB，trauma score（CIS，ISS，NISS）and length of hospital stay were significantly associated with hemothorax（ P<0.05）. The multivariate Logistic regression analysis showed that locations of rib fracture（including middle chest posterolateral segment，middle chest proximal spinal segment，lower chest posterolateral segment and lower chest proximal spinal segment），pulmonary contusion，thoracic cavity drainage，BUN and trauma score（CIS，ISS，NISS）were significantly associated with hemothorax after rib fracture（ P<0.05）. The ROC curve analysis of continous variables in independent risk factors showed BUN area under the curve（AUC）of 0.587（95% CI 0.529-0.645），CIS AUC of 0.824（95% CI 0.779-0.870），ISS AUC of 0.789（95% CI 0.739-0.840）and NISS AUC of 0.876（95% CI 0.835-0.917）（ P<0.05），and the optimal thresholds for the above variables were 5.0 mmol/L，2.5 points，15 points and 21.5 points，respectively. Conclusion:Locations of rib fracture（including the middle chest posterolateral segment，middle chest proximal spinal segment，lower chest posterolateral segment，lower chest proximal spinal segment），pulmonary contusion，thoracic cavity drainage，BUN，trauma score（CIS，ISS，NISS）are independent risk factors for hemothorax after rib fracture. BUN>5.0 mmol/L and trauma score（CIS>2.5 points，ISS>15 points，NISS>21.5 points）have significant values in predicting hemothorax.