The utility of nodule volume in the context of malignancy prediction for small pulmonary nodules.
BACKGROUND
An estimated 150,000 pulmonary nodules are identified each year, and the number is likely to increase given the results of the National Lung Screening Trial. Decision tools are needed to help with the management of such pulmonary nodules. We examined whether adding any of three novel functions of nodule volume improves the accuracy of an existing malignancy prediction model of CT scan-detected nodules.


METHODS
Swensen's 1997 prediction model was used to estimate the probability of malignancy in CT scan-detected nodules identified from a sample of 221 patients at the Medical University of South Carolina between 2006 and 2010. Three multivariate logistic models that included a novel function of nodule volume were used to investigate the added predictive value. Several measures were used to evaluate model classification performance.


RESULTS
With use of a 0.5 cutoff associated with predicted probability, the Swensen model correctly classified 67% of nodules. The three novel models suggested that the addition of nodule volume enhances the ability to correctly predict malignancy; 83%, 88%, and 88% of subjects were correctly classified as having malignant or benign nodules, with significant net improved reclassification for each (P<.0001). All three models also performed well based on Nagelkerke R2, discrimination slope, area under the receiver operating characteristic curve, and Hosmer-Lemeshow calibration test.


CONCLUSIONS
The findings demonstrate that the addition of nodule volume to existing malignancy prediction models increases the proportion of nodules correctly classified. This enhanced tool will help clinicians to risk stratify pulmonary nodules more effectively.
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Florida College of Medicine, Gainesville, FL.
Hiren J
HJ
Mehta
Department of Radiology and Radiological Sciences, Department of Medicine, Medical University of South Carolina, Charleston, SC.
James G
JG
Ravenel
Division of Biostatistics and Epidemiology, Department of Medicine, Medical University of South Carolina, Charleston, SC.
Stephanie R
SR
Shaftman
Division of Biostatistics and Epidemiology, Department of Medicine, Medical University of South Carolina, Charleston, SC; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical University of South Carolina, Charleston, SC.
Nichole T
NT
Tanner
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical University of South Carolina, Charleston, SC.
Luca
L
Paoletti
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical University of South Carolina, Charleston, SC.
Katherine K
KK
Taylor
Department of Community Health Sciences, Brock University, St. Catharines, ON, Canada.
Martin C
MC
Tammemagi
Pulmonary & Sleep Center of the Valley, Weslaco, TX.
Mario
M
Gomez
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Florida College of Medicine, Gainesville, FL.
Paul J
PJ
Nietert
Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA.
Michael K
MK
Gould
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical University of South Carolina, Charleston, SC. Electronic address: silvestri@musc.edu.
Gerard A
GA
Silvestri
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011336:Probability; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*