Development and psychometric properties of three scales employing "what matters most" to assess cultural aspects of intersectional HIV-related and cancer stigma among people living with HIV in Hanoi, Vietnam.

People living with HIV have disproportionate cancer risk and are a priority population for cancer prevention and control efforts globally, including in Vietnam. HIV-related and cancer stigma independently and intersectionally hinder access to and uptake of prevention and treatment. Using formative qualitative research that used the "What Matters Most" theoretical framework and cognitive interviewing, we developed three culturally-tailored stigma scales for people living with HIV in Hanoi, Vietnam (i.e., for anticipated intersectional HIV-related and cancer stigma, internalized HIV-related stigma, and public cancer stigma [i.e., negative community attitudes]). Scales were administered to 100 people living with HIV alongside existing widely-used stigma scales and measures of cancer prevention-related constructs. This initial psychometric validation supported that each scale has two subscales reflecting how cultural aspects both shape and protect against stigma, strong reliability (ranging from = 0.76-0.91, = 0.78-0.91), and strong convergent validity with corresponding existing scales for internalized HIV-related stigma and public cancer stigma. The culturally-tailored intersectional and cancer-only scales were correlated at least as highly with the measured cancer prevention-related constructs compared to the existing public cancer stigma scale. Culturally-tailored, intersectional scales could help monitor and address stigma, ultimately promoting HIV and cancer prevention, control, and treatment.