Supporting Pharmacovigilance Signal Validation and Prioritization with Analyses of Routinely Collected Health Data: Lessons Learned from an EHDEN Network Study

INTRODUCTION

Individual case reports are the main asset in pharmacovigilance signal management. Signal validation is the first stage after signal detection and aims to determine if there is sufficient evidence to justify further assessment. Throughout signal management, a prioritization of signals is continually made. Routinely collected health data can provide relevant contextual information but are primarily used at a later stage in pharmacoepidemiological studies to assess communicated signals.

OBJECTIVE

The aim of this study was to examine the feasibility and utility of analysing routine health data from a multinational distributed network to support signal validation and prioritization and to reflect on key user requirements for these analyses to become an integral part of this process.

METHODS

Statistical signal detection was performed in VigiBase, the WHO global database of individual case safety reports, targeting generic manufacturer drugs and 16 prespecified adverse events. During a 5-day study-a-thon, signal validation and prioritization were performed using information from VigiBase, regulatory documents and the scientific literature alongside descriptive analyses of routine health data from 10 partners of the European Health Data and Evidence Network (EHDEN). Databases included in the study were from the UK, Spain, Norway, the Netherlands and Serbia, capturing records from primary care and/or hospitals.

RESULTS

Ninety-five statistical signals were subjected to signal validation, of which eight were considered for descriptive analyses in the routine health data. Design, execution and interpretation of results from these analyses took up to a few hours for each signal (of which 15-60 minutes were for execution) and informed decisions for five out of eight signals. The impact of insights from the routine health data varied and included possible alternative explanations, potential public health and clinical impact and feasibility of follow-up pharmacoepidemiological studies. Three signals were selected for signal assessment, two of these decisions were supported by insights from the routine health data. Standardization of analytical code, availability of adverse event phenotypes including bridges between different source vocabularies, and governance around the access and use of routine health data were identified as important aspects for future development.

CONCLUSIONS

Analyses of routine health data from a distributed network to support signal validation and prioritization are feasible in the given time limits and can inform decision making. The cost-benefit of integrating these analyses at this stage of signal management requires further research.

Real-time PCR melting analysis with fiber optic SPR enables multiplex DNA identification of bacteria

A fiber optic surface plasmon resonance (FO-SPR) technology was developed that enables simultaneous quantification and identification of multiple DNA targets on the same platform. The bioassay was based on the hybridization/melting of DNA-coated Au nanoparticles on the FO-SPR sensor when targets are present. The multiplex concept was successfully demonstrated on two related bacteria and for detection of multiple mutations in sequences. In conclusion, FO-SPR technology shows a great potential as a next generation in vitro diagnostics tool.

Enabling fiber optic serotyping of pathogenic bacteria through improved anti-fouling functional surfaces

Significant research efforts are continually being directed towards the development of sensitive and accurate surface plasmon resonance biosensors for sequence specific DNA detection. These sensors hold great potential for applications in healthcare and diagnostics. However, the performance of these sensors in practical usage scenarios is often limited due to interference from the sample matrix. This work shows how the co-immobilization of glycol(PEG) diluents or 'back filling' of the DNA sensing layer can successfully address these problems. A novel SPR based melting assay is used for the analysis of a synthetic oligomer target as well as PCR amplified genomic DNA extracted from Legionella pneumophila. The benefits of sensing layer back filling on the assay performance are first demonstrated through melting analysis of the oligomer target and it is shown how back filling enables accurate discrimination of Legionella pneumophila serogroups directly from the PCR reaction product with complete suppression of sensor fouling.

Immunohistochemical detection of cyclin E in transitional cell carcinoma

PURPOSE

It is known that expression disorders of cell cycle regulators play an important role in the development and prognosis of various malignant tumors. Cyclin expression changes during the cell cycle. This work aimed to analyse the expression of cyclin E in transitional cell carcinoma (TCC) and also to compare the expression of cyclin E with tumor stage and histological grade as well as to determine possible existence of differences in the expression of cyclin E in TCCs of the upper and lower urothelium.

METHODS

Twenty-four cases of TCC of the urinary tract were retrospectively analysed (6 cancers of the renal pelvis, 2 of the ureter and 15 of the bladder; 4 were infiltrative). Immunohistochemical staining for cyclin E of the analysed transitional cancer cells was assessed semiquantitatively: diffuse cyclin E expression + + + (> 50% of all cells), expression in larger groups of cells: + + (up to 50% of all cells), expression in individual cells or small cell clusters: + (<10% of all cells), and absence of expression. Tumor stage was based on clinical and morphological criteria. WHO classification (Lyon 2004) was used for determination of the histological grade.

RESULTS

Non-parametric Spearman's correlation showed that there was no statistically significant correlation between tumor stage and expression of cyclin E (ρ = -0331, p> 0.05). Also, no statistically significant correlation between grade and the expression of cyclin E (ρ = -0077, p> 0.05) was found. x2 test results showed no statistically significant difference (x2 = 2.136, p = 0.775) in the expression of cyclin E between upper and lower urothelium.

CONCLUSION

This study showed non significant decreased expression of cyclin E with poor differentiation, muscle invasion and upper/lower urothelium. Expression of cyclin E decreased with increasing histological grade and stage of the tumor.

Effects of primer-template mismatches on the polymerase chain reaction: human immunodeficiency virus type 1 model studies

We investigated the effects of various primer-template mismatches on DNA amplification of an HIV-1 gag region by the polymerase chain reaction (PCR). Single internal mismatches had no significant effect on PCR product yield while those at the 3'-terminal base had varied effects. A:G, G:A, and C:C mismatches reduced overall PCR product yield about 100-fold, A:A mismatches about 20-fold. All other 3'-terminal mismatches were efficiently amplified, although the G:G mismatches appeared to be more sensitive to sequence context and dNTP concentrations than other mismatches. It should be noted that mismatches of T with either G, C, or T had a minimal effect on PCR product yield. Double mismatches within the last four bases of a primer-template duplex where one of the mismatches is at the 3' terminal nucleotide, in general, reduced PCR product yield dramatically. The presence of a mismatched T at the 3'-terminus, however, allowed significant amplification even when coupled with an adjacent mismatch. Furthermore, even two mismatched Ts at the 3'-terminus allowed efficient amplification.