THE COST OF DIAGNOSIS - A COMPARISON OF 4 DIFFERENT STRATEGIES IN THEWORK-UP OF SOLITARY RADIOGRAPHIC LUNG LESIONS

Introduction: Due to the large numbers of negative results of sputum e xaminations in the face of malignant disease, we used a decision analy tic model to determine whether, and under what conditions, sputum cyto logy (Spt) might have a cost-effective role to play in the approach to lung lesions. Methods: We constructed a decision analytic model to co mpare the utility of Spt, image-directed fine-needle aspiration (FNA), bronchoscopic examination (Bronch), and open biopsy (OBx) in the eval uation of lung lesions. Prevalence and cost data were derived from loc al databases and diagnosis-related groups. Diagnostic sensitivity (sen s) and specificity (spec) of the tests were derived from the literatur e and local data. Output of the model was lowest cost per correct mali gnant diagnosis and included surgical treatment costs. We did not atte mpt to model survival data or morbidity. Sensitivity analyses were per formed using cost, test sensitivity, and lesion size variables. Result s: In the baseline case, a patient who is a surgical candidate with le sion size 2.8 cm, prevalence of malignancy=0.67, FNA sens=0.95, Bronch sens=0.80, Spt sens=0.51, OBx is the best initial procedure with a co st per correct diagnosis of $12,888. Sputum examination has the highes t cost per correct diagnosis of $63,424. FNA and bronchoscopy have cos t per correct diagnosis of $21,543 and $16,615, respectively. Sens ana lysis shows that OBx is the preferred strategy in the workup of lung l esions in patients who are surgical candidates older than 30 years of age. Spt is the preferred strategy only when the patient is not a surg ical candidate, the lesion size is large (>4.7 cm), and only if sputum sens is >0.45. Conclusions: Spt is not cost-effective in clinical pra ctice, except when the patient has a large clinically unresectable les ion and the laboratory can demonstrate sufficient test sens.