Characterisation and utility of thiopurine methyltransferase and thiopurine metabolite measurements in autoimmune hepatitis.

BACKGROUND & AIMS: Corticosteroids alone or in conjunction with azathioprine (AZA) is the standard treatment in autoimmune hepatitis (AiH). Individual variations in thiopurine (TP) metabolism may affect both drug efficacy and toxicity. Our aim was to investigate the utility of thiopurine methyltransferase (TPMT) as well as thioguanine nucleotide (TGN) and methylthioinosine monophosphate (meTIMP) metabolite measurements with regard to clinical outcome. METHODS: Two hundred thirty-eight patients with AiH were included in this cross-sectional study. TPMT status was assessed in all patients, while TGN and meTIMP were measured in patients with ongoing TP medication. Clinical outcome was evaluated by liver tests and the ability to withdraw steroids. RESULTS: TPMT genotyping (n=229) revealed 207 (90.4%) wild-type and 22 heterozygous patients. One hundred forty-three patients had ongoing TP therapy with AZA (n=134) or mercaptopurine (MP; n=9); response was judged as complete response (CR) in 113 patients and partial response (PR) in 30 patients. Both TP dose (1.64 vs 1.19 mg/kg; p=0.012) and TPMT activity (14.3 vs 13.5; p=0.05) were higher in PR, resulting in similar TGN levels (PR: 121 pmol/8 x 10(8) red blood cells [RBC]; CR: 113 pmol/8 x 10(8) RBC; p=0.33) but higher meTIMP levels in PR (1350 vs 400 pmol/8 x 10(8) RBC; p=0.004). Patients able to withdraw steroids or who were using 5 mg prednisolone daily were treated with lower TP doses than patients on higher steroid doses (1.15 vs 1.18 vs 1.82 mg/kg; p<0.001). CONCLUSIONS: TP metabolite measurements are of clinical value in AiH patients who do not respond to standard TP treatment and for the identification of a shifted metabolism, which may demand an alternative treatment strategy.

Resource use and societal costs for Crohn's disease in Sweden.

BACKGROUND: The usual onset of Crohn's disease (CD) is between 15 and 30 years of age, thus affecting people during their most economically productive period in life. METHODS: This study intended to estimate societal costs and health-related quality of life (HRQoL) in Swedish patients in different stages of CD. Cross-sectional data on disease activity (measured with the Harvey-Bradshaw Index [HBI]), direct medical resource use, work productivity, and HRQoL (assessed using the 15D instrument) were collected for 420 patients by questionnaires to patients, to the treating physician, and from medical records. Based on HBI, current treatment, and response to treatment, patients were classified into the following disease states: Remission, Response, Active, Refractory, and Surgery. RESULTS: The average 4-week cost per patient in 2007 was estimated at €721 (USD 988), of which 64% was due to lost productivity. The total 4-week cost of care was €255 (USD 349) in Remission, €831 (USD 1138) in Response, €891 (USD 1220) in Active, €1360 (USD 1864) in Refractory, and €16984 (USD 23269) in Surgery. HBI was the most important predictor of costs of care--a 1-point increase in HBI increased total costs by 25% (P < 0.001). HRQoL differed between the disease states: 0.92 in Remission, 0.90 in Response, 0.82 in Active, 0.81 in Refractory, and 0.77 in Surgery. CONCLUSIONS: Patients in remission have the lowest costs and the highest HRQoL. Patients responding to treatment have lower costs of care than patients with high disease activity who are not treated or do not respond to treatment. Thus, total costs of care might be reduced by efficient treatment.

Monitoring of thiopurine metabolites in patients with inflammatory bowel disease-what is actually measured?

Azathioprine and 6-mercaptopurine are often used in the treatment of patients with inflammatory bowel disease (IBD). They are prodrugs and undergo a complex metabolism to active and inactive metabolites. Thiopurine treatment is monitored in many laboratories by measuring metabolite concentrations in erythrocytes (red blood cells). The metabolites of interest are not measured directly but as hydrolysis products, which can be produced from several metabolites. The aim of this study was to examine which metabolites are actually measured during routine monitoring. Samples from 18 patients treated with a thiopurine were analyzed by a typical routine high-performance liquid chromatography method for therapeutic drug monitoring and by a newly developed specific method measuring thioguanosine monophosphate (TGMP), thioguanosine diphosphate (TGDP), and thioguanosine triphosphate (TGTP), as well as methylthioinosine monophosphate (meTIMP), and the results were compared. 6-Thioguanine nucleotide (TGN) values detected by the routine method were 69% (range 40%-90%) of the sum of TGMP, TGDP, and TGTP measured by the specific method. TGTP and TGDP contributed 85% (range 78%-90%) and 14% (range 10%-21%) of the TGN total, respectively. Thioguanosine was not found in any patient sample. The concentration of meTIMP obtained by the routine method was 548% of the value obtained by the specific method (range 340%-718%). The difference in TGN measurements between the routine and specific methods can be explained by low hydrolysis efficiency in the routine method, although the most likely explanation for the difference in meTIMP values is that not yet identified metabolites are codetermined in the routine high-performance liquid chromatography method. Concentrations reported as TGN during therapeutic drug monitoring of thiopurine metabolites consist of TGDP and TGTP with a minor contribution of the TGMP. Concentrations reported as meTIMP or methyl mercaptopurine consist in part of meTIMP, but other not yet identified metabolites are codetermined.

Budd-Chiari syndrome in Sweden: epidemiology, clinical characteristics and survival - an 18-year experience.

BACKGROUND: The exact incidence and prevalence of Budd-Chiari syndrome (BCS) is unknown in the general population. Published reports differ in terms of the clinical characteristics, effects of therapy and survival. AIMS: To investigate the epidemiology, clinical presentation and survival in patients with BCS. METHODS: Retrospective multicentre study in Sweden reviewing the medical records of all patients with BCS 1986-2003, identified from the computerised diagnosis database of 11 hospitals, including all university hospitals and liver transplantation centres. RESULTS: Forty-three patients with BCS were identified, of whom nine (21%) had concomitant portal vein thrombosis. The mean age-standardised incidence and prevalence rates in 1990-2001 were calculated to be 0.8 per million per year and 1.4 per million inhabitants respectively. Myeloproliferative disorders (38%), thrombophilic factors (31%) and oral contraceptives (30%) were common aetiological factors. Two or more risk factors were present in 44%. In 23%, no risk factor was evident. The median follow-up time was 2.7 years. Seventy-two percent were on anticoagulant therapy during follow-up. Transjugular intrahepatic portosystemic shunting, surgical shunting procedures and liver transplantation were performed in 4, 6 and 18 patients respectively. Nineteen patients died. The overall transplantation-free survival at 1, 5 and 10 years was 47, 28 and 17% respectively. CONCLUSIONS: Budd-Chiari syndrome is a rare disorder; the mean age-standardised incidence and prevalence rates in Sweden in 1990-2001 were calculated to be 0.8 per million per year and 1.4 per million inhabitants respectively. The presence of a myeloproliferative disorder was a common aetiological factor in our cohort and about half of the patients had a multifactorial aetiology. The transplantation-free survival was poor.