Gout flares and health-related quality of life in people living with gout: a prospective cohort study in primary care

Abstract

Background
Gout is a common inflammatory arthritis affecting an estimated 2.5% of the UK population. The hallmark of gout is sudden onset, extremely painful acute inflammatory flares, which are strongly associated with impaired health-related quality of life (HRQOL) in cross-sectional studies. Little is known about change in gout flares and HRQOL over time, and the factors associated with worse outcomes.

Methods
In a three-year prospective cohort study in primary care, people registered with gout reported gout flares and completed the Gout Impact Scale (GIS) subscales, 36-Item Short-Form Health Survey Physical Function subscale (SF-36 PF10) and Health Assessment Questionnaire Disability Index (HAQ-DI) at baseline, 6, 12, 24 and 36 months. Responders to the follow-up surveys and non-participants were compared to investigate attrition bias. Latent class growth analysis (LCGA) was used to identify and describe distinct gout flare trajectory classes. Linear mixed models were used to describe the factors associated with change in GIS subscales (disease-specific HRQOL), SF-36 PF10 and HAQ-DI (generic HRQOL).

Results
Responders had slightly less frequent gout flares and better HRQOL at baseline compared with non-participants. Six distinct gout flare trajectory classes were identified. The infrequent flare class had the lowest mean serum urate level and the highest proportion of participants taking allopurinol, whilst frequent flare classes had more participants who were socioeconomically deprived, obese, and had chronic kidney disease and oligo/polyarticular flares. Factors associated with deterioration in both disease-specific and generic HRQOL included more frequent gout flares, oligo/polyarticular flares, using allopurinol, body pain, worse pain severity, and worse depression score.

Conclusion
Gout flare trajectory classes with distinct characteristics and the factors associated with change in HRQOL were identified in people living with gout in primary care, highlighting people at risk of worse outcomes over three years and at greatest need of targeted interventions.