Urine salicylate levels in patients with ulcerative colitis treated with mesalamine can indicate treatment adherence and predict the risk for future nonadherence, according to recent results.
Researchers evaluated 93 patients with ulcerative colitis (UC) on maintenance therapy with mesalamine along with 20 controls. Random urine samples were collected at baseline and measured for salicylates and 5-aminosalicylic acid (5-ASA). Adherence to mesalamine was assessed via patient enrollment questionnaires and prescription refills during a 6-month period.
The mean urine salicylate level in patients was 60 mg/dL; controls had a mean of 6 mg/dL (P=.002 for difference). Investigators said a correlation existed between salicylate and 5-ASA metabolite levels in urine samples (r2=0.9; P<.0001), and urine salicylate levels above 15 mg/dL identified patients who had taken mesalamine vs. controls who had not. AUC measurement was 0.9, with 95% sensitivity and 77% specificity.
No correlation was observed between self-reported adherence and urine salicylate. Twenty-seven percent of patients indicating they were “high adherers” had low levels of urine salicylate. Among 20 patients with urine salicylate levels comparable to those of controls, the mean self-reported adherence was 85%, and 75% reported having missed less than one dose in the past 5 days.
Patients with low adherence, based on prescription refills, had significantly lower salicylate levels than those with high adherence (32 mg/dL compared with 62 mg/dL, P=.04). An increased risk of nonadherence over 6 months was observed among patients with salicylate levels below 15 mg/dL upon enrollment (RR=2.7; 95% CI, 1.1-7.0).
Alan C. Moss
“Patients’ claims that they are taking their mesalamine regularly are unreliable,” Alan C. Moss, MD, FACG, director of translational research at the Center for Inflammatory Bowel Disease at Beth Israel Deaconess Medical Center in Boston, told Healio.com. “The reality is that many patients skip doses or pills. We know from other studies that these patients are more likely to experience disease relapses, and have higher health care costs over time. The widely available urine test that we used could be applied in the clinic to ‘flag’ patients who may not be adhering to their mesalamine regimen.”
Disclosure: Dr. Moss reported receiving grant funding from Shire Inc., which provided study funding, and Salix Pharmaceuticals.