A marked improvement has occurred in the survival of patients with cystic fibrosis with an FEV(1) less than 30% predicted. Secondary analyses suggest that some of this improvement may be due to use of recombinant human DNase.

Overall improvements in resources and organization are accompanied by reduced mortality, shorter admissions and greater access to specialist services. There remains, however, considerable variation in the quality of secondary care provided between units.

Background: Assays for cardiac troponin (cTn) have undergone improvements in sensitivity and precision in recent years. Increased rates of outliers, however, have been reported on various cTn platforms, typically giving irreproducible, falsely higher results. We aimed to evaluate the outlier rate occurring in patients with elevated cTnI using a contemporary and high-sensitivity assay. Methods: All patients with elevated cTnI (up to 300 ng/L) performed over a 21-month period were assayed in duplicate. A contemporary assay (Abbott STAT Troponin-I) was used for the first part of the study and subsequently a highsensitivity assay (Abbott STAT High-Sensitive Troponin-I) was used. Outliers exceeded a calculated critical difference (CD) (CD ¼ z ¡2  SD Analytical ) where z ¼ 3.5 (for probability of 0.0005) and critical outliers also were on a different side of the decision level. Results: The respective outlier and critical outlier rates were 0.22% and 0.10% for the contemporary assay (n ¼ 4009) and 0.18% and 0.13% for the high-sensitivity assay (n ¼ 3878). There was no significant reduction in outlier rate between the two assays ( 2 ¼ 0.034, P ¼ 0.854). Fifty-six percent of outliers occurred in samples where cTn was an 'add-on' test (and was stored and refrigerated prior to assay). Conclusion: Despite recent improvements in cTn methods, outliers (including critical outliers) still occur at a low rate in both a contemporary and high-sensitivity cTnI assay. Laboratory and clinical staff should be aware of this potential analytical error, particularly in samples with suboptimal sample handling such as add-on tests.