A model-based economic evaluation of four newborn screening strategies for cystic fibrosis in Flanders, Belgium.

Objectives: The most cost-effective newborn screening strategy for cystic fibrosis (CF) for Flanders, Belgium, is unknown. The aim of this study was to assess the cost-effectiveness of four existing newborn screening strategies for CF: IRT-DNA (immunoreactive trypsinogen, cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation analysis), IRT-PAP (pancreatitis-associated protein), IRT-PAP-DNA, and IRT-PAP-DNA-EGA (extended CFTR gene analysis).Methods: Using data from published literature, the cost-effectiveness of the screening strategies was calculated for a hypothetical cohort of 65,606 newborns in Flanders, Belgium. A healthcare payer perspective was used, and the direct medical costs associated with screening were taken into account. The robustness of the model outcomes was assessed in sensitivity analyses.Results: The IRT-PAP strategy was the most cost-effective strategy in terms of costs per CF case detected (€9314 per CF case detected). The IRT-DNA strategy was more costly (€13,966 per CF case detected), but with an expected sensitivity of 93.4% also the most effective strategy, and was expected to detect 2.2 more cases of CF than the IRT-PAP strategy. The incremental cost-effectiveness ratio of IRT-DNA vs. IRT-PAP was €54,180/extra CF case detected. The IRT-PAP-DNA strategy and the IRT-PAP-DNA-EGA strategy were both strongly dominated by the IRT-PAP strategy.Conclusion: The IRT-PAP strategy was the most cost-effective strategy in terms of costs per CF case detected. However, the strategy did not fulfil the European Cystic Fibrosis Society guidelines for sensitivity and positive predictive value. Therefore, the more costly and more effective IRT-DNA strategy may be the most appropriate newborn screening strategy for Flanders.

Cost effectiveness of newborn screening for cystic fibrosis: a simulation study.

BACKGROUND: Early detection of cystic fibrosis (CF) by newborn screening (NBS) reduces the rate of avoidable complications. NBS protocols vary by jurisdiction and the cost effectiveness of these different protocols is debated. OBJECTIVE: To compare the cost effectiveness of various CF NBS options. METHODS: A Markov model was built to simulate the cost effectiveness of various CF-NBS options for a hypothetical CF-NBS program over a 5-year time horizon assuming its integration into an existing universal NBS program. NBS simulated options were based on a combination of tests between the two commonly used immunoreactive trypsinogen (IRT) cutoffs (96th percentile and 99.5th percentile) as first tier tests, and, as a second tier test, either a second IRT, pancreatic-associated protein (PAP) or CFTR mutation panels. CFTR mutation panels were also considered as an eventual third tier test. Data input parameters used were retrieved from a thorough literature search. Outcomes considered were the direct costs borne by the Quebec public health care system and the number of cases of CF detected through each strategy, including the absence of screening option. RESULTS: IRT-PAP with an IRT cutoff at the 96th percentile is the most favorable option with a ratio of CAD$28,432 per CF case detected. The next most favorable alternative is the IRT1-IRT2 option with an IRT1 cutoff at the 96th percentile. The no-screening option is dominated by all NBS screening protocols considered. Results were robust in sensitivity analyses. CONCLUSION: This study suggests that NBS for cystic fibrosis is a cost-effective strategy compared to the absence of NBS. The IRT-PAP newborn screening algorithm with an IRT cutoff at the 96th percentile is the most cost effective NBS approach for Quebec.

Integrated device for online sample buffer exchange, protein enrichment, and digestion.

An integrated sample treatment device, composed of a membrane interface and a monolithic hybrid silica based immobilized enzymatic reactor (IMER), was developed for the simultaneous sample buffer exchange, protein enrichment, and online digestion, by which for the sample buffer, the acetonitrile content was reduced to approximately 1/10 of the initial one, and the pH value was adjusted from approximately 3.0 to approximately 8.0, compatible for online trypsin digestion. Furthermore, the signal intensity of myoglobin digests was improved by over 10 times. Such an integrated device was successfully applied to the online treatment of three protein eluates obtained by reverse-phase liquid chromatography (RPLC) separation, followed by further protein digest analysis with microreverse-phase liquid chromatography-electrospray ionization-tandem mass spectrometry (microRPLC-ESI-MS/MS). The experimental results showed that the performance of such an integrated sample treatment device was comparable to that of the traditional offline sample treatment method, including lyophilization and in-solution digestion. However, the consumed time was reduced to 1/192. All these results demonstrate that such an integrated sample treatment device could be further online coupled with protein separation, peptide separation, and identification, to achieve high-throughput proteome analysis.

The energetic cost of induced fit catalysis: Crystal structures of trypsinogen mutants with enhanced activity and inhibitor affinity.

The contribution of induced fit to enzyme specificity has been much debated, although with little experimental data. Here we probe the effect of induced fit on enzyme specificity using the trypsin(ogen) system. BPTI is known to induce trypsinogen to assume a trypsinlike conformation. Correlations are observed between BPTI affinity and the values of k(cat)/K(m) for the hydrolysis of two substrates by eight trypsin(ogen) variants. The slope of both correlations is -1.8. The crystal structures of the BPTI complexes of four variant trypsinogens were also solved. Three of these enzymes, K15A, DeltaI16V17/D194N, and DeltaI16V17/Q156K trypsinogen, are 10- to 100-fold more active than trypsinogen. The fourth variant, DeltaI16V17 trypsinogen, is the lone outlier in the correlations; its activity is lower than expected based on its affinity for BPTI. The S1 site and oxyanion hole, formed by segments 184A-194 and 216-223, are trypsinlike in all of the enzymes. These structural and kinetic data confirm that BPTI induces an active conformation in the trypsin(ogen) variants. Thus, changes in BPTI affinity monitor changes in the energetic cost of inducing a trypsinlike conformation. Although the S1 site and oxyanion hole are similar in all four variants, the N-terminal and autolysis loop (residues 142-152) segments have different interactions for each variant. These results indicate that zymogen activity is controlled by a simple conformational equilibrium between active and inactive conformations, and that the autolysis loop and N-terminal segments control this equilibrium. Together, these data illustrate that induced fit does not generally contribute to enzyme specificity.

Assessment of the role of pancreatic proteases in human abdominal aortic aneurysms and occlusive disease.

Previous studies on the pathogenesis of abdominal aortic aneurysms have shown both elastase-like activity in the aortic wall and a decreased elastin content. The present study, using specific radioimmunoassays for pancreatic elastase 2 (IRE2) and cationic trypsin(ogen) (IRCT), investigates the concentrations of these proteases which are known to circulate in blood, in abdominal aortic aneurysms. Aortic specimens were obtained from 32 patients with aneurysms and 21 patients with atherosclerotic occlusive disease. Aortic tissue, obtained at autopsy from young adults, served as controls. Elastase-like activity was 300% and 800% higher, respectively, in aortic homogenates from aneurysms in comparison to occlusive disease and control aortic tissue. This was associated with 1.4-fold higher level of IRE2 and 2.7-fold higher levels of IRCT as compared to occlusive disease. Although there was no significant difference in the aortic collagen concentration among all 3 groups, the elastin content of aneurysmal aorta was 85% and 74% lower, respectively, in comparison to control and occlusive aorta. The results of this investigation demonstrate the presence of pancreatic elastase 2 and cationic trypsin(ogen) in abdominal aortic aneurysmal tissue and suggest that circulating pancreatic proteases contribute to the pathophysiology of aneurysms of the infrarenal aorta.