Adherence to Urate-Lowering Therapy Supports Target Benchmarks in Gout

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Only slightly more than half of older adults with gout achieved an optimal serum uric acid (SUA) level within 12 months of urate-lowering therapy (ULT) initiation, according to a new population-based retrospective cohort study in Canada.

Adherence to ULT remained suboptimal, although improving annually, with data pointing to better adherence and higher allopurinol starting doses demonstrating the strongest association of achieving a target SUA level.

“This is the largest population-level study to date evaluating the attainment of a treat-to-target benchmark in older adult patients with gout on ULT, incorporating process measures including ULT adherence,” wrote the investigative team, led by Timothy S.H. Kwok MD, MSc, division of rheumatology, the University of Toronto.

Achievement of a target SUA level of <360 µmol/L or 6 mg/dL through ULT adherence has been linked to a decrease in flares, reductions in tophi, and an improvement in quality of life. Guidelines, including those from the American College of Rheumatology (ACR) and European Alliance of Associations for Rheumatology (EULAR) guidelines, have endorsed this approach to achieve target SUA levels.

However, irrespective of these guideline-based recommendations, evidence has cited only 34% of patients on ULT as achieving their SUA targets. Real-world adherence to ULT to achieve target goals remains crucial, but data have suggested only up to 71% of patients remain adherent.

A focus on the older adult population is important, given the burden of gout increases with age. In this study, Kwok and colleagues sought to evaluate the proportion of patients achieving an SUA level <360 µmol/L, within 12 months of starting ULT and the associated demographic characteristics.

A retrospective cohort of patients with gout aged ≥66 years dispensed ULT between January 2010 and March 2019 were enrolled for study. Successful treat-to-target was determined as attainment of SUA levels <360 µmol/L within 12 months of beginning ULT.

Investigators also investigated ULT adherence as a key process measure, with assessment by trend over time and by prescriber specialty, particularly its impact on treat-to-target parameters. For the analysis, multi-level logistic regression, clustered by ULT prescriber, estimated odds ratios (ORs) to determine the factors associated with achieving successful treat-to-target SUA levels by 12 months.

The study cohort comprised 44,438 patients (mean age, 76 years), of which 64.4% were male, prescribed ULT during the study period, primarily allopurinol (99.6%). Of the cohort, 30,057 (67.6%) patients had completed ≥1 SUA test during the first 12 months.

Among this population, 52.3% of patients achieved SUA treat-to-target parameters within 12 months of initiation, improving from 45.2% in 2010 to 61.2% in 2019 (P <.0001). The mean number of days to achieve the target SUA level was 128.

Overall, Kwok and colleagues found only 55.3% of patients adhered to ULT. Adherence rates improved from 48.3% of patients in 2010 to 61.8% in 2019 (P <.0001). Adherence improved yearly in all specialties (P <.008) except for rheumatology (P = .103).

According to the logistic regression model, independent factors associated with achieving SUA target levels included febuxostat use (OR, 11.40; 95% CI, 5.10 - 25.43), but only 88 patients dispensed the drug, as well as ULT adherence (OR, 5.17; 95% CI, 4.89 - 5.47).

Other key factors included allopurinol starting doses >50 mg (OR, 2.53; 95% CI, 2.14 - 2.99), colchicine/oral corticosteroid co-prescription (OR, 1.24; 95% CI, 1.14 - 1.34), and prescriptions from a rheumatologist, compared with other specialties.

Kwok and colleagues noted further quality improvement initiatives are warranted to enhance adherence to ULT, with these identified modifiable factors critical for creating initiatives to benefit quality care in gout.

“Our results indicate that treat-to-target SUA levels are influenced by physician, patient, and prescription-level factors, of which, ULT adherence was strongly associated with successful T2T, though was poor on a population level,” Kwok and colleagues wrote.

References

1. _{Kwok TSH, Kuriya B, Hawker G, et al. Adherence and Treat to Target Benchmarks in Older Adults with Gout Initiating Urate Lowering Therapy in Ontario, Canada: A Population-based Study. Arthritis Care Res (Hoboken). Published online June 3, 2024. doi:10.1002/acr.25380}