Age at date of test was determined by subtracting the patient's date of birth from the dateof test. Individuals younger than age 10 and older than age 80 were excluded. The patientswere divided into age groups from 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79.Results: There were 26,450 patients who underwent HACA testing who met inclusioncriteria. The rate of negative HACA was 81.9% of the10,155 patients aged 10-19; 80% ofthe 4004 patients aged 20-29; 78.9% of the 3831 patients aged 30-39; 79.9% of patientsaged 40-49; 79.9% of the 2735 patients aged 50-59; 77.8% of the 1600 patients aged from60-69; and 74.8% of the 616 patients aged 70-79 (see Figure 1). This reveals a statisticallysignificant decrease in the rate of HACA negativity by decade of life (Chi square, p<.0001).Conclusion: Older patient age was associated with a significant increase of HACA in patientstreated with infliximab in clinical practice.

Figure 1: Rate of negative HACA by decade of life.

Sa2041

Hematologic Monitoring After Immunomodulator Initiation in Veterans WithInflammatory Bowel Disease: A Practice AuditJason K. Hou, Jennifer R. Kramer, Peter Richardson, Shubhada Sansgiry, Hashem El-Serag

Background/Aims: Immunomodulator medications (IMM) play a vital role in the care ofpatients with inflammatory bowel disease (IBD) as steroid sparing agents. However, theyare associated with hematologic suppression even in patients with normal thiopurine methyl-transferase activity. Practice guidelines recommend monitoring of hematologic parametersafter the initiation of IMM in IBD patients. However, adherence to hematologic monitoringafter IMM initiation has not been previously reported in large practice settings. The aim ofthis study was to evaluate the prevalence and determinants of hematologic monitoring afterIMM initiation among a national cohort of veterans with IBD. Methods: We identified acohort of VA users with IBD from fiscal years 2003-2009 using the national Veterans Affairs(VA) administrative datasets: Inpatient and Outpatient Medical SAS® Datasets and laboratorytests from Decision Support System. IBD patients were identified by a previously validatedalgorithm using International Classification of Diseases, 9th Revision diagnosis codes forCrohn's disease (555.x) or ulcerative colitis (556.x). Subjects with filled prescriptions forazathioprine, 6-mercaptopurine, and methotrexate were included, with the date of thefirst filled IMM prescription defined as the IMM index date. Based on the least stringentinterpretation of practice guidelines, the primary endpoint was the proportion of subjectswho had a white blood cell count (WBC) completed within 90 days of the IMM index date.Determinants of WBC monitoring were identified by univariate and multivariate analyses.Results: A total of 4,325 unique IBD patients were identified with filled IMM prescriptions,of whom 73% were Caucasian, 10% African American, 3% Hispanic, and 14% of other orunknown race; 93% were male. Overall, only 39% of subjects completed a WBC within 90days of IMM index date. Monitoring rates increased over time, from 31% in 2003 to 52%in 2009. There was variability of monitoring frequency by facility, ranging from 0-77%. Inmultivariate analyses, older age at IMM index date was associated with a lower rate ofmonitoring (65+ vs. < 35 years of age, OR 0.79, 95%CI 0.64-0.98). In addition, increasedfrequency of VA encounters (13+ visits per year vs. < 3 visits year, OR 17.20, 95%CI 10.59-27.94), and more recent year of IMM index date (OR 1.13, 95% CI 1.09-1.17) wereassociated with increased rates of hematologic monitoring. Race, region, concomitant biologicmedication, comorbidity, and facility load of IBD patients on IMM were not significantlyassociated with hematologic monitoring. Conclusions: Hematologic monitoring among vet-erans with IBD after IMM initiation is low with wide variability based on facility. Providerand system wide interventions are needed to improve adherence and reduce variability ofIMM monitoring across facilities.

Sa2042

A Simple Test for Mesalamine Use: Random Urine Salicylate LevelsAnne E. Gifford, Anders Berg, Conor Lahiff, Gary L. Horowitz, Alan C. Moss

Background: Patients with IBD are frequently non-adherent with mesalamine therapy, butthere are few reliable tools to assess non-adherence in the clinic setting. Ingested mesalamineis excreted in the urine as 5-ASA or N-acetyl-5-ASA, salicylates which should be readilydetectable in urine by a standard salicylate test. We sought to determine the correlationbetween urinary salicylate levels, and urinary 5-ASA and N-Acetyl-5-ASA levels as measuredby liquid chromatography-tandem massspectrometry (LC-MS/MS). Methods: Patients withulcerative colitis (UC) prescribed mesalamine were prospectively enrolled to provide anunexpected spot urine sample at a clinic visit. Time since last reported dose, and dosingregimen were recorded. Urinary salicylate levels and creatinine were measured by standardcolorimetric assay, and 5-ASA and N-acetyl-5-ASA determined by LC-MS/MS. The "totalsalicylate equivalents" were obtained by converting all salicylate metabolite results into mmol/L units and summing their total, and these were then converted from mmol/L into μg/mlusing the molecular weight of salicylate. In addition, samples of urine from individuals nottaking mesalamine were also tested for salicylate levels by colorimetric assay. Statistical

S-387 AGA Abstracts

analysis was conducted using JMP. Results: 82 patients with UC and 20 controls wereenrolled in the study. The majority of UC patients (93%) were prescribed mesalamine attotal daily dose > 2.4 g/day. The mean time since last dose before urinalysis was 10 hours(range 1-31.5 hours). Median spot urinary salicylate level was 358 μg/mL [range 0-3580μg/mL] in patients prescribed mesalamine, and 3 μg/mL [range 0-38 μg/mL] in controls.In the control group, 90% of spot urine salicylate levels were less than 10 μg/mL. In patientswith UC, the median levels of total salicylate equivalents was 476 μg/mL [range 15-4920],5-ASA 50 μg/mL [range 0-2303] and N-acetyl-5-ASA 607 μg/mL [range 1-3992] respectivelyby LC-MS/MS. Urinary salicylate levels by colorimetric assay were closely correlated withLC-MS/MS levels of total salicylate equivalents (R2 = 0.91 at P < 0.001) (Figure 1). Whena receiver operating characteristic (ROC) curve was generated, a colorimetric urinary salicylatethreshold of 45μg/mL had a sensitivity of 94% and specificity of 100% for the identificationof mesalamine users (AUC 0.98). Conclusions: There is a high correlation between salicylatelevels and 5-ASA metabolite levels in the urine of patients taking mesalamine. Urine salicylatelevels above a threshold of 45ug/mL indicated mesalamine use in this cohort. Spot urinarysalicylate levels may provide a simple, readily available, method to test mesalamine adherence.

Sa2043

Adherence to Monthly Thiopurine Blood Work Monitoring Declines OverTime in Adults With Inflammatory Bowel DiseaseJonathan Wong, Richard N. Fedorak, Karen Wong, Karen I. Kroeker

BACKGROUND Patient adherence to medical therapy is usually studied in the context ofmedication use. Thiopurines, such as azathioprine (AZA) and 6-mercaptopurine (6-MP),are frequently used to maintain remission in inflammatory bowel disease (IBD) patients.Patients on thiopurines are recommended to complete routine surveillance blood testing asa consequence of thiopurine associated leukopenia and elevated liver enzymes. AIM Theaim of this study is to determine the adherence of patients with IBD on thiopurines tomonthly surveillance blood test monitoring and to determine if the adherence changed overtime. METHODS A patient search was conducted in a university gastroenterology patientdatabase to identify IBD patients currently on thiopurines. Patients were instructed on themonthly blood testing required and adherence was reinforced at each clinic visit and withyearly laboratory re-ordering of blood testing. Charts were reviewed for demographic informa-tion, diagnosis and blood test frequency and results, which include white blood cell (WBC)and liver enzymes. For the purpose of this study, only blood tests measured over 20 daysapart were counted as monthly blood tests. Patients were grouped by the number of yearson thiopurine therapy and cross-tabulated with number of venipunctures per year. Datawas analyzed using Microsoft Excel and SPSS. RESULTS The initial patient search identified348 IBD patients on thiopurines. 165 patients were included in this study. Reasons forexclusion include: did not live in the local area and so could not confirm if all blood testswere available (163); patients were in clinical trials (4); and incomplete patient records (16).Mean age was 36.5±1.1 years. 48% were male, and 76% had Crohn's disease and 24%ulcerative colitis. The average number of blood tests, per year (mean±SE), during the firstyear of thiopurine treatment was significantly higher (7.7±0.32) than for patients usingthiopurines for more than one year (5.3±0.17), p=5.47x10-11. CONCLUSION IBD patients onthiopurines completed routine surveillance blood tests less frequently than the recommendedmonthly monitoring. Furthermore, adherence to blood test monitoring was significantlyhigher in the first year of thiopurine treatment and markedly declined in subsequent years.Table 1. Frequency of venipuncture per year varies by duration of thiopurine use

(Data reported as number and % of patients in that year of thiopurine use; Chi-squared,p=0.000015)

AG

AA

bst

ract

s