A cost minimization approach to the diagnosis of skeletal neoplasms

Percutaneous needle aspiration (PNA) has been widely used to diagnose bone malignancies. Successful aspirates hinge on the ability of the operator to obtain an adequate or diagnostic sample, and a skilled cytologist to make a diagnosis on needle aspirates. False-negative aspirates could pose a serious problem. This study is designed to evaluate the cost-effectiveness of PNA in the diagnosis of skeletal neoplasms using a cost minimization approach.

All PNA performed over a 44-month period were reviewed retrospectively. Ninety-four skeletal biopsies were performed to diagnose a clinically or roentgenographically suspicious lesion: 69 for a suspected metastatic malignancy, and 25 for a suspected primary malignancy. The PNA results were collected and reviewed, sensitivities and specificities were determined (compared with open biopsy results or clinical follow-up as the gold standards), and the probabilities were applied to a decision tree. Charges were obtained from the patient's billing and converted into costs by a cost-charge ratio. Sensitivity analysis was performed to determine the costs of each branch of the decision tree, and ultimately the final cost of the two strategies: (1) PNA for all suspected neoplasms followed by open biopsy for negative and non-diagnostic PNA results, or (2) open biopsy for all suspected neoplasms.

In diagnosing a suspected metastatic skeletal neoplasm, PNA had a sensitivity of 88%, a specificity of 100%, and a non-diagnostic result in 3% of cases. Cost analysis determined a savings of $ US 2486 per patient when "PNA strategy" was used instead of "open biopsy strategy". In diagnosing a suspected primary neoplasm, PNA hat a sensitivity 75%, a specificity of 100%, and a non-diagnostic result in 16% of cases. Cost analysis determined a savings of $ US 954 per patient when "PNA strategy" was used instead of "open biopsy strategy". By using "PNA strategy" instead of "open biopsy strategy" at this institution we would have saved $ US 195384 over the 44-month period.

Metastatic skeletal neoplasms could be reliably diagnosed by PNA, and followed by open biopsy if the PNA result is negative or non-diagnostic, at a significant cost saving over open biopsy. Diagnosing primary skeletal neoplasms using "PNA strategy" offers a slight cost saving compared with "open biopsy strategy", but too few primary skeletal neoplasms were evaluated to recommend the best diagnostic approach.