Point-of-care monitoring of warfarin treatment in community dwelling elderly--A randomised controlled study.

The objective of this study was to assess clinical effectiveness and costs of launching point-of-care monitoring of warfarin treatment in community dwelling frail elderly patients. A prospective multicentre controlled randomised study over 12 months comparing a point-of-care strategy with usual monitoring routines was carried out in primary healthcare centres and anticoagulation clinics in southeast Sweden. The subjects were community dwelling elderly across rural southeast Sweden on chronic warfarin treatment. Main outcome measures were time in therapeutic range (TTR), rate of treatment-related adverse events and costs. The study comprised 103 elderly people (61% women) mean age 86 yrs (range 75-98) treated with warfarin for median 9 yrs (range 1-18). Patients randomised to start point-of-care monitoring (n = 55) showed 75.9% in TTR before trial vs. 72.6% during trial (ns). The patients randomised to continue on usual monitoring routines (n = 48) showed 75.2% in TTR prior to trial vs. 72.9% during trial (ns). The point-of-care monitoring showed potential savings of SEK 624 per patient annually (based partly on effects that were not statistically significant). The study shows that point-of-care monitoring of warfarin treatment in community dwelling elderly in rural areas is as effective as usual monitoring routines and that it may offer savings to society.

The international normalized ratio according to Owren in liver disease: interlaboratory assessment and determination of international sensitivity index.

INTRODUCTION: The international normalized ratio (INR) is used to prioritize liver disease patients for transplantation. Previous studies have shown high interlaboratory variability in Quick-based INR determinations in samples of patients with liver disease. We assessed Owren-based INR reagents for analyzing INR in patients with liver disease. Further, we determined the difference between international sensitivity index (ISI) for patients on vitamin K antagonists (ISIVKA) and ISI for patients with liver disease (ISIliver). PATIENTS AND METHODS: Twenty patients with liver disease were included, 10 with INR 1.8-3.6 (group A1) and 10 with INR 1.2-1.5 (group C1). Plasma from these patients was analyzed for Owren-based INR in eight Swedish laboratories using either of following reagents: SPA+, Owrens PT or Nycotest PT. To determine ISI liver, the reference thromboplastin RBT/05 and additional 41 patients with liver disease and 20 normal controls were included. ISIVKA was determined according to the WHO procedure. The difference between the ISIVKA and ISIliver was calculated. RESULTS: The coefficients of variance for the Owren based INR methods were 6.2% in group A1, 3.9 % in group C1 and 5.3% for all patients. The difference between ISIVKA and ISIliver were -0.4%, -0.7% and -0.2% for SPA+, Owrens PT and Nycotest PT respectively. CONCLUSIONS: Interlaboratory variation in INR analyses according to Owren in patients with liver disease is low and the difference between ISIVKA and ISIliver is below 10% with this method. ISIVKA can therefore be used in the INR calibration, for the Owren reagents studied, when analyzing plasma from patients with liver disease.

Ruling out cardiac failure: cost-benefit analysis of a sequential testing strategy with NT-proBNP before echocardiography.

OBJECTIVES: To estimate the possible economic benefit of a sequential testing strategy with NT-proBNP to reduce the number of echocardiographies. METHODS: Retrospective study in a third-party payer perspective. The costs were calculated from three Swedish counties: Blekinge, Östergötland, and Uppland. Two cut-off levels of NT-proBNP were used: 400 and 300 pg/mL. The cost-effectiveness of the testing strategy was estimated through the short-term cost avoidance and reduction in demand for echocardiographies. RESULTS: The estimated costs for NT-proBNP tests and echocardiographies per county were reduced by 33%-36% with the 400 pg/mL cut-off and by 28%-29% with the 300 pg/mL cut-off. This corresponded to a yearly cost reduction of approximately €2-5 million per million inhabitants in these counties. CONCLUSION: The use of NT-proBNP as a screening test could substantially reduce the number of echocardiographies in the diagnostic work-up of patients with suspected cardiac failure, as well as the associated costs.

Local INR calibration of the Owren type prothrombin assay greatly improves the intra- and interlaboratory variation. A three-year follow-up from the Swedish national external quality assessment scheme.

In 1999, a simplified procedure for calibration of the Owren prothrombin time (Owren PT) assay was introduced by a working group of the organisation for national quality assurance in laboratory medicine in Sweden. The new protocol allowed local calibration by means of only two lyophilised national plasma calibrators and expression of results as an international normalized ratio (INR). This is our report of a three-year follow-up involving the analysis of data from all laboratories, in hospitals (n=88 in 2002) and primary health care units (n=246 in 2002) that perform the Owren PT assay in Sweden. The interlaboratory variation was significantly improved after the introduction of the new calibration procedure. For the larger hospital-based laboratories, the mean coefficient of variation (CV) was reduced from 7.9% to 5.2% (p<0.0001) when analysing test materials with INR range 2-4. In the higher INR range (>4), the CV was reduced even further, from 10.4% to 6.8% (p<0.0001). The corresponding results from smaller laboratories in the primary health care units showed a similar decrease in CV from 8.2% to 5.7% in the INR range 2-4 (p<0.0001). At the INR range >4, the CV was reduced from 9.5% to 7.8%. The intralaboratory variation was also improved for both types of laboratory categories. This study shows an improved precision, with CV less than 6% at the therapeutic INR range, for both hospital-based laboratories and smaller laboratories in the primary health care system. The results indicate that the Owren PT assay is well suited for local INR calibration employing only two calibrant plasmas in a simplified procedure.