Gout Studies Presented at ISPOR

VBCR - August 2012, Volume 1, No 3 - Gout

By Barbara Schwedel

Washington, DC—Gout affects ap­proximately 1% to 2% of the US population. The results of 2 recent studies involving patients with gout were presented at a poster session during the 2012 International Society for Pharma­coeconomics and Outcomes Research (ISPOR) annual meeting.

Uric Acid Levels Linked to Patient Medication Adherence

Patients who are not adhering to their uric acid–lowering therapy are more likely to not reach their uric acid goals than patients who are adherent to therapy, according to the results of the first study on gout that was presented at ISPOR.

This study was a retrospective analysis of the potential link between patient adherence to allopurinol therapy and the attainment of uric acid goals. Urate-lowering therapies are effective in lowering uric acid levels in patients with gout, but evidence has shown that their use is often suboptimal, and that many patients with gout have poor outcomes.

Allopurinol is the most often prescribed medication used for the management of uric acid levels in this patient population. Nevertheless, many patients who are prescribed this medication do not reach the goal serum urate of <6.0 mg/dL, the level that is associated with improved outcomes in patients with gout.

Nazia Rashid, PharmD, MS, Outcomes Research Pharmacist, and colleagues of Kaiser Permanente, Downey, CA, evaluated the characteristics of patients, prescribers, and adherence patterns of patients with gout who were initiating treatment with allopurinol.

The investigators identified 9288 patients (mean age, 60 years; men, 78%) who were newly diagnosed with gout between January 1, 2007, and June 31, 2010, and were new users of allo­purinol. All patients had ≥1 comorbid condition. Patients were followed for at least 12 months after the initiation of allopurinol therapy.

The mean medication possession ratio (MPR) was 92% for patients who were at goal compared with 77% for patients not at goal.

Among all the patients who had more than 1 allopurinol prescription and were adherent to therapy (MPR >80%), 1793 (65%) reached their goal uric acid level (<6.0 mg/dL) and 2604 (40%) did not reach that goal. By contrast, among the patients who were not adherent to allopurinol therapy (MPR <80%), only 956 (35%) reached the goal uric acid level of <6.0 mg/dL compared with 3935 (60%) patients who did not reach that goal uric acid level.

Overall, men who were older and patients who visited a rheumatologist within 6 months preceding their first allopurinol prescription or measurement of their first uric acid level were more adherent to the regimen and were at goal (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.02-1.43). Older patients (OR, 1.02; 95% CI, 1.01-1.02) and those who were at least 80% adherent (OR, 2.82; 95% CI, 2.56-3.11) were more likely to be at uric acid goal.

At the end of the study, 2749 (30%) of the patients (mean age, 63 years; men, 71%) achieved the goal uric acid level of <6.0 mg/dL and 6539 (70%) of the patients (mean age, 59 years; men, 81%) did not achieve that goal.

This study shows that 60% of new allopurinol users are not adherent to uric acid–lowering therapy, resulting in patients not reaching their goal uric acid levels. Patient factors such as age, care by a rheumatologist, and adherence were associated with achieving uric acid goal levels.

The investigators suggest that new strategies, such as targeting specific factors to improve the care of patients with gout and to enhance patient adherence to therapy, are needed.

Validating Patient-Reported Outcomes in Gout

Patient-reported outcomes (PROs) are gaining in importance in clinical studies and in medical research overall. The goal of the second study on gout was to use a direct-to-patient strategy that combines information reported by patients (ie, PROs) and medical record information to evaluate the validity of PROs, based on data contained in the patients’ medical records.

Elisa Cascade, MBA, Vice President of MediGuard.org, Rockville, MD, and her colleagues compared PROs and medical record information of 50 pa­tients with gout from MediGuard.org to see if the information will match.

Adult members (aged 18-80 years) of MediGuard.org, a free medication monitoring service, were randomly invited to participate by e-mail if they had a self-reported gout diagnosis or self-reported use of a gout medication. The first 50 eligible and consenting participants completed an online survey and a release form. The release forms were provided to Ms Cascade’s colleagues at Out­comes Health Information Solu­tions in Marietta, GA, who then requested a copy of the participants’ medical charts from their physicians.

A total of 120 US members (10% of 1250 invitees) clicked on the e-mail link provided (before the study closed with 50 consenting participants). Of these 120 invitees, 5 (4%) declined to participate because of the medical record release requirement. Up to 33% of additional patients discontinued by closing their browser window, with reasons not provided.

The collected age and sex data compare favorably to US national data, and 38 (76%) of the 50 requested medical charts were obtained. Of the 38 total available charts, 35 (92%) contained a gout diagnosis, 2 mentioned a gout medication (ie, allopurinol or colchicine), and 1 chart did not contain any mention of gout or a gout medication.

These results indicate, the investigators noted, that “patients can be successfully recruited directly for observational study designs that include PRO and medical record data.” Further­more, these results show that PROs match well with information in the patient’s medical records.

Although concerns exist regarding the validity of self-reported diagnoses, nearly all medical charts confirmed the study’s patient-reported data; based on this small study, data completeness or validation of data can reach a level of more than 75%. New studies with more patients are ongoing to see if these results could be confirmed with more participants.

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Last modified: May 21, 2015
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