Background/Purpose: ACR 2012 management guidelines for tophaceous gout (TG) recommend urate lowering therapies (ULT) to achieve a target serum uric acid (SUA) of < 6.0 mg/dl, but in some patients, a SUA of ≤ 5.0 mg/dl may be appropriate. Despite new ULT, allopurinol remains the most commonly used drug. Yet, achievement of target SUA in clinical practice is subpar, with comorbidities frequently limiting optimum ULT use.  We evaluated a cohort with TG and significant comorbidities to determine the applicability of recent ACR guidelines, that is, achievement of target SUA of less than 6 mg/dl and 5 mg/dl, respectively.  

Methods: VA administrative data over a 3-year period was used to identify patients with gout (ICD 9 codes: 274.xx) who had at least two related outpatient visits, and BMI > 28 Kg/m².  Medical records from primary care and rheumatology clinics were filtered electronically for the prefix ‘toph’ and then searched manually for presence of ‘tophaceous gout’ or ‘tophus’ to identify TG subset. Demographic data, including age, race, BMI, comorbidities [hypertension (HTN), chronic renal injury (CRI) and diabetes mellitus (DM)], SUA, serum creatinine and creatinine clearance (CrCl) were extracted from Veterans Affairs Decision Support System (DSS) database. Natural Language Processing was used to extract gout behavioral modification counseling (BMC). Colchicine and allopurinol use was recorded for each patient; for allopurinol, dose and dates of therapy were obtained for patients with TG. Data were analyzed for number and percent of patients achieving target SUA <6 mg/dl and ≤ 5 mg/dl.

Results:

Clinical characteristics of the 1576 eligible patients are shown in (Table).  One hundred and twenty (73.2%) patients with TG were on allopurinol. SUA was evaluated at least once in 119 (99.2%) patients. Seventy-eight patients (65%) achieved target SUA < 6 mg/dl at least once during follow up and 44 (36.7%) achieved SUA levels ≤ 5 mg/dl. Forty-two patients had CrCl < 60 ml/min; 24 (57.1%) and 15 (35.7%) achieved SUA < 6 mg/dl and ≤ 5 mg/dl, respectively.  Patients with a CrCl ≥ 60 ml/min had mean allopurinol dose of 257.7 mg/day [54/78 (47.4%) SUA < 6 mg/dl], significantly greater than patients with CrCl < 30 ml/min who received a mean of 69.0 mg/day [3/6 (50%) SUA < 6 mg/dl]. However, both groups had similar mean SUA levels [6.52 ± 2.1 vs. 6.03 ± 1.06 (p < 0.948)], respectively. Mean allopurinol dose for patients with SUA < 6 mg/dl and ≥ 6 mg/dl was 255.1 (± 124.5) and 157.7 (± 109.4) (p < 0.001), respectively. There were no differences in demographics, severity of CRI, frequency of comorbidities, BMC or number of rheumatology visits between patients achieving SUA < 6 mg/dl and those who remained above target values.

Table

Conclusion: Despite frequent associated comorbidities the majority of TG patients can achieve target SUA levels. In CRI, BMC and allopurinol pharmacokinetics may have significant roles in achieving SUA target.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/chronic-renal-injury-does-not-prevent-achievement-of-target-serum-uric-acid-in-tophaceous-gout/