Objective: To assess patient-reported functional ability and its relationship with symptoms in primary biliary cirrhosis (PBC).
Methods: Functional status was assessed in a representative cohort of 75 patients with PBC using the Patient-Reported Outcome Measure Information System Health-Assessment Questionnaire (PROMIS-HAQ) functional assessment tool and was related to both symptom severity at the point of assessment (assessed using the PBC-40 and Orthostatic Grading Scale) and symptom severity change over the previous 4 years. Functional status in the PBC group was compared with primary sclerosing cholangitis (cholestatic liver disease) and community controls.
Results: Functional impairment at follow-up (PROMIS-HAQ) was substantial in PBC significantly higher than that in both primary sclerosing cholangitis and community controls. PROMIS-HAQ domain scores confirmed that patients with PBC had significant impairment in arising, eating, walking, reach and grip and activity, but not dressing or hygiene. Functional impairment correlated positively with greater PBC-40 Fatigue, Cognitive and Social and Emotional domains and higher orthostatic symptoms. Over 4 years, total symptom burden increased significantly (P=0.03). The predominant factor was rise in Cognitive domain scores indicating worsening cognitive symptoms (P<0.0001). Change in PBC-40 Cognitive, Social and Emotional scores (2005-2009) strongly predicted functional ability in 2009. Multivariate analysis confirmed that PROMIS-HAQ scores were predicted independently by PBC-40 Social and Emotional scores (P=0.02; β=0.3) and orthostatic symptoms (P=0.04; β=0.3).
Conclusion: PBC associates with substantial functional impairment. PBC symptom distribution evolves over time, with cognitive symptoms making ever-greater contribution to overall symptom burden. The major potentially modifiable determinant responsible for the functional impairment appears to be orthostatic symptoms.