A Nationwide Study of Spine Metastasis in the Korean Adult population: Prognostic Factor Analysis

Abstract

Purpose: The aim of this nationwide study of adult Koreans was analyzing haracteristics, medical utilization rate, and survival rate of patients with newly diagnosed spine metastasis, ultimately to suggest prognostic factors influencing survival. We also aimed to understand the current state of stereotactic radiosurgery (SRS) and other treatment modalities in relation to spine metastasis. Methods and Materials: Data for patients with metastatic spine tumors were extracted from the Korean Health Insurance Review and Assessment Service database. The data included the age, sex, health insurance type, co-morbidities, medical cost, and hospital stay duration. Hospital stay duration and medical costs per person for a single calendar year were calculated. In addition, survival rates of metastatic spine tumor patients according to the primary tumor sites were evaluated. In a multivariate analysis, factors which affect the survival period were evaluated. The SRS group received SRS at least once within a year of their diagnoses, while the non-SRS group did not receive SRS. Results: Increased rates of incidence of spine metastasis were associated with increases in age, higher diagnosis year, and a higher number of comorbidities (P= <0.0001). The 6 most prevalent primary tumor sites were the lung, hepatobiliary, breast, colon, stomach, and prostate. Among patients with tumors in these areas, the total average annual medical costs, including inpatient and outpatient services, ranged from 12,734 USD (prostate) to 15, 556 USD (lung). Among patients with tumors in these 6 area, the total average annual hospital stay duration, including as an inpatient and outpatient, ranged from 70.8 d (stomach) to 78.7 d (colon). The median overall survival duration of the metastatic spine tumor patients was 191 d. There were significant differences between the SRS and the non-SRS group with regard to medical costs (23,276 vs. 18,458 USD, P=0.001) and the duration (days) of medical service (101.3 vs. 86.5, P=0.023). Age, female sex, certain primary tumor sites (breast, prostate cancer), synchronous metastasis were significant positive prognostic factors affecting survival period. Conclusions: Age, sex, comorbidities, certain primary tumor sites, and synchronous metastasis significantly affect the survival periods of patients with metastatic spine tumors.