Rethinking wellbeing measurement: learning from a scale development study with adolescents living with HIV in Zimbabwe

Adolescents living with HIV (ALHIV) in Eastern and Southern Africa experience substantial challenges around medication adherence, treatment, care, mental health and wellbeing. Although interventions such as Zvandiri aim to strengthen mental health and wellbeing to impact HIV treatment outcomes, available measures often focus on negative outcomes or rely on positive psychology instruments developed in high-income settings. These tools may not adequately capture culturally embedded, relational and fluctuating dimensions of wellbeing among ALHIV. We describe the development of the Zvandiri Character Strength (ZCS) scale and draw methodological lessons for culturally grounded wellbeing measurement. The multi-stage scale-development process (2023-2025) comprised a scoping and systematic review, qualitative interviews and focus group discussions, expert panel input, construct and item prioritisation with ALHIV, cognitive interviews, iterative item reduction, and exploratory factor and Rasch analyses. An initial item bank was reduced to a 53-item candidate scale, then to the ZCS 38 and finally ZCS 25, based on quantitative analyses and participant feedback. The ZCS 25 was subsequently assessed using retrospective pretest, post-test and follow-up administration. The review identified conceptually overlapping positive psychological constructs, many of which are measured using instruments developed in high-income settings and not adequately validated for ALHIV in sub-Saharan Africa. Qualitative work highlighted connectedness, happiness, hope, motivation, optimism, and perseverance as key. In addition, discussions highlighted how wellbeing was relational, contextually situated, and often co-occurring with distress. Quantitative testing showed highly positive responses, disordered thresholds, ceiling effects, weak internal structure and fluctuating retrospective ratings. Participant feedback suggested that positive responses were likely due to affirmations and partly linked to social desirability. In conclusion, the ZCS scale did not support a single interpretable total score, but the process of its development offers important methodological lessons. Future measurement should begin with clearer construct definition, response-process validation, domain-level testing, and explicit decisions about whether the measure aims to capture lived wellbeing, domain-specific positive outcomes or intervention-relevant change.