Measurement properties of the Activities-specific Balance Confidence (ABC) scale in community-dwelling adults aged 50 years and older: a COSMIN systematic review

AIM: To systematically review and grade the measurement properties of the Activities-specific Balance Confidence (ABC) scale in community-dwelling older adults using the COSMIN framework. METHODS: Five electronic databases were searched through July 2025 from inception. Eligible studies included adults aged 50 years or older and examined the ABC scale in any version or translation. Methodological quality was evaluated using the COSMIN Risk of Bias checklist, and the certainty of the evidence was graded with the COSMIN-adapted GRADE approach. The protocol was registered with PROSPERO (ID: CRD420251178952). RESULTS: A total of 22 studies were included, covering the ABC-16 (n = 16), ABC-6 (n = 5), and ABC-S (n = 1) in 11 languages. Internal consistency (α = 0.86-0.99) and test-retest reliability (ICC = 0.82-0.99) were consistently sufficient with moderate certainty. Structural and construct validity were generally supported. In contrast, content validity was primarily assessed during cross-cultural adaptations, measurement error was seldom assessed, and cross-cultural validity and responsiveness were rarely tested. The Arabic ABC-16 showed the strongest overall evidence and was categorized as ready for use (Category A). Versions in Chinese-Canadian, Cantonese, Mandarin ABC-6, Brazilian Portuguese, Persian, German, Urdu, Sepedi, Chinese, English (Canadian), and Hindi demonstrated promising properties but require local validation (Category B). Dutch and Mandarin ABC-16 versions as well as the earlier Portuguese version did not meet current COSMIN standards and require re-validation (Category C). CONCLUSION: The ABC scale generally demonstrates strong reliability and validity of balance confidence in older adults. The ABC-16 remains the most comprehensive version, while the ABC-6 provides an efficient screening tool. Category A versions can be considered for use in clinical and research settings. Future work should focus on responsiveness, cross-cultural invariance, and interpretability to strengthen clinical utility.