Background/Purpose:

Gout is the
most common inflammatory arthritis worldwide. Despite its prevalence and the
availability of effective therapies, studies have consistently characterized gout
quality of care to be suboptimal. Suboptimal care has largely been defined by adverse
events or gaps in care while few studies have identified factors to optimize gout
care. The objective of this study was to develop a model of modifiable patient
and provider factors associated with a well-accepted treatment target in gout, achievement
of a serum urate (SU) < 6.0 mg/dL.

Methods:

For this
cross-sectional study, we sent a questionnaire to 1437 gout patients receiving
an allopurinol prescription during a 1-year period. Of these, 886 (62%)
responded and 612 were included for the primary analysis after exclusions. Questionnaire
data was linked to medical and pharmacy records. We hypothesized that five patient/provider
factors would be associated with SU goal attainment < 6.0 mg/dL. The Patient
Activation Measure (PAM^TM) was used to measure, on a 0-100 scale, the
patient’s knowledge, skills and confidence to engage in their own care. The
proportion of days covered (PDC) was used to determine allopurinol adherence
with a PDC ≥ 0.8 considered adherent. For providers, we considered dose
escalation of allopurinol, anti-inflammatory prophylaxis during allopurinol
initiation and low starting dose of allopurinol (≤ 100 mg/dL). Logistic
regression was used to model both medication adherence and SU goal attainment.
The Akaike Information Criterion (AIC) was used to determine the best model,
with lower AIC values indicative of improved model performance.

Results:

Gout
participants were older (mean age 72 ± 11 years), primarily Caucasian (89%) and
men (98%). A vast majority (73%) were adherent to allopurinol over one year of
observation. Factors associated with nonadherence in adjusted analysis were older
age (p<0.001), higher BMI (p =0.007) and thiazide use (p=0.037). Considering
SU goal, medication adherence (OR 2.06), a low allopurinol starting dose (OR
0.23), and dose escalation (OR 2.58) were each independently associated with
attainment (Table). Importantly, a rheumatologist as the initial prescriber (OR
3.88) was associated with SU goal attainment whereas the PAM score was
marginally associated and produced a lower AIC for the model.

Conclusion:

SU goal
attainment with the use of allopurinol appears to be largely driven by factors
related to medication dosing, such as low starting dose or dose escalation, and
medication adherence. While higher patient activation did trend toward greater
SU goal attainment in this study and improved model performance, it did not
reach statistical significance in adjusted analyses. This study suggests that
initial efforts to improve outcomes would benefit most from focus on proper
dosing practices and medication adherence before addressing patient activation
more broadly.