The Effect of Individual and Neighborhood Socioeconomic Status on Gastric Cancer Survival

Chin-Chia Wu,Ta-Wen Hsu,Chia-Hui Yu,Ching-Chih Lee,Yuh-Feng Wang,Chun-Ming Chang,Yinglin Xia

doi:10.1371/journal.pone.0089655

Abstract

PurposeGastric cancer is a leading cause of death, particularly in the developing world. The literature reports individual socioeconomic status (SES) or neighborhood SES as related to survival, but the effect of both has not been studied. This study investigated the effect of individual and neighborhood SES simultaneously on mortality in gastric cancer patients in Taiwan.Materials and MethodsA study was conducted of 3,396 patients diagnosed with gastric cancer between 2002 and 2006. Each patient was followed for five years or until death. Individual SES was defined by income-related insurance premium (low, moderate, and high). Neighborhood SES was based on household income dichotomized into advantaged and disadvantaged areas. Multilevel logistic regression model was used to compare survival rates by SES group after adjusting for possible confounding factors.ResultsIn patients younger than 65 years, 5-year overall survival rates were lowest for those with low individual SES. After adjusting for patient characteristics (age, gender, Charlson Comorbidity Index Score), gastric cancer patients with high individual SES had 68% risk reduction of mortality (adjusted odds ratio [OR] of mortality, 0.32; 95% confidence interval [CI], 0.17–0.61). Patients aged 65 and above had no statistically significant difference in mortality rates by individual SES group. Different neighborhood SES did not statistically differ in the survival rates.ConclusionGastric cancer patients aged less than 65 years old with low individual SES have higher risk of mortality, even under an universal healthcare system. Public health strategies, education and welfare policies should seek to correct the inequality in gastric cancer survival, especially in those with lower individual SES.

Highlights

Gastric cancer is a leading cause of death worldwide, with the 989,600 new cases in 2008 accounting for 8% of cancer cases
Gastric cancer patients aged less than 65 years old with low individual socioeconomic status (SES) have higher risk of mortality, even under an universal healthcare system
Education and welfare policies should seek to correct the inequality in gastric cancer survival, especially in those with lower individual SES

Summary

Materials and Methods

Ethics statement This study was approved by the Institutional Review Board of Buddhist Dalin Tzu Chi General Hospital, Taiwan. The data for this study were collected from Taiwan’s National Health Insurance Research Database (NHIRD) for the years 2002 to 2006. This dataset is organized and managed by Taiwan’s National Health Research Institutes but collected by Taiwan’s NHI Program. Pearson’s chi-square test was used for categorical variables such as gender, level of urbanization, geographic region of residence, CCIS, treatment modality, tumor extent and hospital characteristics (teaching level, ownership and caseload). The multilevel logistic regression model was used to analyze the relationship between the main outcomes of the different SES groups and those of the reference group after adjusting for hospital, and patient demographics age, gender, CCIS, urbanization and area of residence, adjuvant treatment modality (radiotherapy, chemotherapy, chemoradiotherapy) and hospital characteristics. A two-sided P-value (P,0.05) was considered significant

Results

Conclusion

Introduction

Discussion