Objective
To identify modifiable patient and provider factors associated with allopurinol adherence and the achievement of a serum urate (sUA) goal in gout.
Methods
We identified a retrospective cohort of gout patients, newly initiated on allopurinol. All patient data came from administrative datasets at a large integrated health delivery system. Patients were > 18 years old at time of initial allopurinol dispensing, and had 12 months or more of membership and drug eligibility prior to the index date. Allopurinol adherence was defined as a proportion of days covered ≥ 0.80, evaluated during the first 12 months of observation after the initial dispensing. Multivariable logistic regression was used to examine factors associated with allopurinol nonadherence and attaining a sUA concentration < 6.0 mg/dl.
Results
We identified 13,341 gout patients with incident allopurinol use (mean age 60 years, 78% male). Of these, 9,581 patients (72%) had sUA measured both at baseline and during follow-up. Only 3,078 patients (32%) attained sUA target of < 6.0 mg/dl during follow-up. Potentially modifiable factors associated with treatment adherence and obtaining sUA goal in the multivariable analysis included concomitant diuretic use, prescriber specialty, and allopurinol dosing practices. Adherent patients were 2.5-fold more likely than nonadherent patients to achieve a sUA < 6.0 mg/dl during observation.
Conclusion
Among gout patients initiating allopurinol in this study, 68% did not reach sUA goal and 57% of patients were nonadherent. Modifiable factors, including allopurinol dose escalation, treatment adherence, rheumatology referral, and concomitant medication use could be important factors to consider in efforts aimed at optimizing gout treatment outcomes.
No funding was provided to support this research study. The authors report no potential conflicts of interest relevant to this article. All authors contributed to the study concept and design. Benedict and Spence performed data analysis and interpretation. The manuscript was written by Benedict, with assistance from Spence and Rashid. All authors reviewed and contributed to manuscript revisions. Spence is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Parts of this study were presented at the AMCP Managed Care and Specialty Pharmacy Annual Meeting; San Francisco, California; April 19-22, 2016.
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