Comorbidity clusters in people with gout: an observational cohort study with linked medical record review

Objective. To investigate how comorbid conditions cluster in patients with gout in a UK primary care population. Methods. A cross-sectional study was performed using baseline data from a primary-care-based prospective observational cohort of people aged >= 18 years with gout. Participants with gout were identified through primary care medical records. Factor analysis was performed to obtain distinct clusters of comorbidity variables including obesity, hypertension, diabetes mellitus, hyperlipidaemia, coronary heart disease, heart failure, chronic kidney disease (CKD) and cancer. Hierarchical cluster analysis of patient observations was also performed to identify homogenous subgroups of patients based on combinations of their comorbidities. Results. Four distinct comorbidity clusters (C1-C4) were identified in 1079 participants [mean (S.D.) age 65.5 years (12.5); 909 (84%) male]. Cluster C1 (n = 197, 18%) was the oldest group and had the most frequent attacks of gout; 97% had CKD. Participants in C2 (n = 393, 36%) had isolated gout with few comorbidities but drank alcohol more frequently. In cluster C3 (n = 296, 27%), hypertension, diabetes mellitus, hyperlipidaemia, coronary heart disease and/or CKD were prevalent, and urate-lowering therapy was prescribed more frequently than in other clusters. All patients in C4 (193, 18%) had hypertension and were more likely to be obese than other clusters. Conclusion. Four distinct comorbidity clusters were identified. People with multiple comorbidities were more likely to receive allopurinol. Tailoring of treatments depending on cluster and comorbidities should be considered.