Page 54 - Predicting survival in patients with spinal bone metastasesL

CHAPTER IV
MATERIALS AND METHODS
In this single center retrospective cohort study, all patients treated for metastases in the spinal column between January 2001 and December 2010 at a tertiary referral hospital in the Netherlands were included. Patients were identified through database searches linking treatment and diagnostic codes and through database searches based on surgical coding. Information on date of death was obtained from medical records or by contacting the general practitioner.
Local treatment consisted of external beam radiotherapy for pain or minor neurologic deficit, surgery for rapidly progressive or severe neurologic deficit and instability, or a combination of both treatment modalities. Concomitant systemic anticancer treatments such as chemotherapy and bisphosphonates were considered to be secondary to the local treatment. For external validation of the final model, the database of the Dutch Bone Metastasis Study (DBMS) was used14.
Due to the retrospective nature of the study, it is exempt from medical ethics review according to the Dutch Central Committee on Research Involving Human Subjects.
The primary data sources were the patient’s clinical files, radiology reports and admission forms. Baseline variables obtained before start of treatment were gender, age, primary tumor, location and number of SBM, the presence of visceral and/ or brain metastases, the presence of extraspinal bone metastases, pretreatment functioning according to the Karnofsky performance status (KPS)15,16 and neurological functioning according to the Frankel classification17.
The primary tumors were categorized based on the Tomita classification7. The original classification used growth speed alone to assign a primary tumor into one of three groups. However, as growth speed is not the only factor determining survival, we renamed the classification ‘clinical profile’ encompassing other contributing factors such as the availability of effective systemic treatment options for the primary tumor. The clinical profile of a primary tumor was considered to be favorable, moderate or unfavorable.
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