Experience-based ambivalence toward medical opioid use among Japanese adults: a nationwide cross-sectional survey using the barriers questionnaire II

BACKGROUND: Pain is one of the most distressing symptoms in patients with cancer. Although established guidelines now recommend appropriate opioid use, even for mild-to-moderate pain, Japan's prescription volume remains markedly lower than that of Western countries. Public ambivalence, recognizing opioids as effective yet fearing dependence and adverse effects, may contribute to this underuse. However, little is known about how indirect exposure to opioids through family members' cancer treatments shapes such attitudes. This study examined the perceived barriers to and willingness to use medical opioids among cancer-free adults, focusing on the influence of family experiences with opioid use. METHODS: A cross-sectional web-based survey was conducted on July 30, 2025, among 618 Japanese adults aged 20-49 years without a history of cancer. Participants were categorized into three groups: Opioid+ (family with cancer and opioid use), Opioid- (family with cancer but no opioid use), and None (no family history of cancer). Psychological barriers were assessed using the Japanese version of the Barriers Questionnaire II (JBQ-II), comprising an overall score and five subscales. Willingness to use opioids in a hypothetical mild-to-moderate cancer pain scenario was rated on a 10-point Likert scale. Group differences were analyzed using Kruskal-Wallis and Steel-Dwass tests (two-tailed p < 0.05). RESULTS: Compared with the None group, the Opioid + group showed significantly higher scores for overall JBQ-II (3.23 vs. 3.11, p < 0.01), Physiological Effects (3.47 vs. 3.32, p < 0.05), Harmful Effects (3.32 vs. 3.12, p < 0.001), and Disease Progression (3.65 vs. 3.39, p < 0.01), but lower Fatalism scores (2.25 vs. 2.46, p < 0.05). Willingness to use medical opioids was also higher in the Opioid + group (7.43) than in the Opioid- (6.55, p < 0.01) and None groups (6.59, p < 0.01). CONCLUSIONS: Indirect exposure to opioids through family members' cancer treatment was associated with ambivalent attitudes, characterized by greater recognition of barriers alongside increased willingness to use medical opioids. Addressing this experience-based ambivalence through evidence-based education, individualized counseling using the JBQ-II, and family-involved communication support may help promote the safe and appropriate use of medical opioids in Japan's cultural and public health contexts. CLINICAL TRIAL NUMBER: Not applicable.