High frequency of incomplete or non-response to azathioprine and/or mercaptopurine limit their use in Crohn's disease.
Non-adherence is considered to be of relevance for ineffectiveness.
Dr Matthias Schwab and colleagues from Germany assessed adherence to thiopurines in Crohn's disease out-patients treated in a single gastroenterology practice.
Patients were eligible for inclusion if they received azathioprine and/or mercaptopurine for at least 3 months.
After follow-up of 3 months, the team assessed adherence to azathioprine and/or mercaptopurine by quantitation of relevant thiopurine metabolite levels in red blood cells.
The team also used patients' self-reports by a standardized questionnaire.
The research team prospectively included 65 patients.
|Therapeutic drug monitoring had a concordance rate of 75%|
|Alimentary Pharmacology & Therapeutics|
The team reported that 6 patients had metabolite profiles indicative of non-adherence.
Self-assessed questionnaire revealed non-adherence in 7% of patients.
Therapeutic drug monitoring and self-assessment as 2 independent methods had a concordance rate of 75%.
The researchers found that metabolite levels and self-assessed adherence were not different between patients in remission compared with those with active disease.
Dr Schwab's team concludes, "Out-patients with Crohn's disease treated in a single gastroenterology practice had a satisfactory adherence to thiopurine therapy."
"Different measures of adherence applied to the same patient suggest comparable levels."
"Therapeutic drug monitoring appears to be a reliable tool to assess adherence to thiopurines in clinical practice."