OBJECTIVES: Rare genetic disorders of obesity including Bardet-Biedl Syndrome (BBS) are characterized by early onset obesity, hyperphagia, and multi-systemic complications. Symptoms of Hyperphagia (SoH) and Impacts of Hyperphagia (IoH) are novel questionnaires designed to assess severity of hyperphagia symptoms and their impact on patients and caregivers. As part of the CARE-BBS study, we evaluated the performance of these scales.

METHODS: CARE-BBS was a multi-country cross-sectional survey study of adult caregivers of patients with BBS experiencing obesity and hyperphagia. In addition to the SOH and IOH questionnaires, other instruments included Impact of Weight on Quality of Life (IWQOL)-Kids Parent Proxy, PROMIS Scale Global Health of Caregiver, Revised Impact on Family Scale (RIOFS), and Work Productivity and Activity Impairment (WPAI): BBS-Caregiver.

RESULTS: 242 eligible caregivers from Canada, Germany, UK, and US completed the survey. Exploratory factor analysis identified 1 factor each for SoH-Proxy, IoH-Proxy, and IoH-Caregiver (weighted eigenvalues: 0.83, 2.03, 2.79, respectively). Strong correlations were observed across SoH/IoH scales (r=0.558-0.798) (all p<.001). Strong internal consistency was observed for IoH-Proxy (Cronbach’s α coefficient=0.66) and IoH-Caregiver (α=0.72) and moderate for SoH-Proxy (α=0.40). All three scales correlated moderately to strongly with school days missed and all domains of IWQOL-Kids except Physical Comfort (range=0.315-0.573, all p<.001). Both Impact scales also correlated moderately with both WPAI-Caregiver total productivity and total activity impairments (range=0.417-0.448, all p<.001). Known-groups analyses indicated significantly worse SoH-proxy scores for caregivers applying more weight management approaches (6-10 vs. 5, or >10). Worse IoH scores were found when caregivers reported greater strain on RIOFS items and worse mental health on PROMIS.

CONCLUSIONS: Caregiver versions of the SoH and IoH scales demonstrated validity, reliability, and consistency for use in a real-world setting. Additional studies to further validate psychometric properties of the scales, including the IOH and SOH patient versions across other health care settings, are recommended.