Even when the studies were divided into subgroups by culture, the level of heterogeneity was not reduced (range 0%–4%), except when heterogeneity was examined for ‘disease progression’ and ‘fear of injection’ in Asian culture. In these cases,the level of heterogeneity was reduced by 79%and 24%, respectively, compared with the crude model. Thus, one might conclude that cultural difference was not the main factor accounting for heterogeneity in this meta-analysis. In this study, heterogeneity might also have been due to differences in patient characteristics,such as age, education, income, and differences in pain intensity, hesitancy in taking and reporting use of opioids,and pain treatment. These issues need to be explored and adjusted in future analyses. Further investigation should prospectively focus on understanding the factors driving differences in Western and Asian patient-perceived barriers of cancer pain management.