The Role of Multivariant Analysis on the Interpretation of FTIR and Raman Spectra

FTIR and Raman spectroscopy are complementary spectroscopic techniques that play an important role in the analysis of molecular structure and the determination of characteristic vibrational bands. Vibrational spectroscopy has a wide range of applications including mainly in physics and biology. Its applications have gained tremendous speed in the field of biological macromolecules and biological systems, such as tissue, blood, and cells. However, the vibrational spectra obtained from the biological systems contain a large number of data and information that make the interpretation difficult. To facilitate the analysis, multivariant analysis comprising the reduction of the dimension of spectrum data and classification of them by eliminating redundancy data, which are obtained from the spectra and does not have any role, becomes critical. In this chapter, the applications of Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and their combination PCA-LDA, which are widely used among multivariant techniques on biological systems will be disclosed.

P845 Impact of Clostridium difficile infection in patients admitted with ulcerative colitis

Background Clostridium diffile (CD) infection it is becoming increasingly more prevalent in general population and especially in patients with inflammatory bowel diseases (IBD). Patients with ulcerative colitis (UC) with CD infection during a flare can present greater morbidity and mortality. The objectives of the study were (a) to evaluate the proportion of CD infection in patients admitted with UC; (b) to compare the rates of colectomy in UC admitted with and without CD infection; (c) to analyse the association between the infection and worse results according to readmissions, need of treatment intensification and hospital stay; and (d) to describe predictive factors associated with worse evolution in patients with CD infections. Methods Cases and controls retrospective study. We included patients admitted due to a flare of UC in our hospital from 2000 to 2018. Variables related to hospital stay, adverse events, need of colectomy in the first year and mortality were collected. We analysed the data with SPSS using chi-square test, Kruskal–Wallis and multivariant analysis to identify factors of bad evolution. Results We analysed 235 admitted patients with UC flare. 62.1% male, mean age 43.6 years old (SD 12). Seventy-two per cent presented extensive colitis and 22% left coliits. 7.7% had perianal disease and 8.7% extraintestinal manifestations. Endoscopic activity was 75.8% Mayo Index 3 and 23% Mayo Index 2. 15.9% of the patients had complications during their hospitalisation related to their disease: 37.8% had toxic megacolon, 11% perforation and 11.2% of the total needed surgery during the hospitalisation. Twenty-eight patients (12.2%) had CD infection, among them 23.5% suffered recurrence infection of CD. This infection was statistically significant related to a higher rate of readmission (48.1% vs. 23%, p = 0.007) and higher rates of colectomy during the first year from the admission (13% vs. 2.9%, p = 0.05). We did not find differences among both groups of patients in terms of complications of their IBD, neither need of treatment intensification, nor mortality. Predictive factors of bad evolution were not identify with multivariant analysis. Conclusion CD infection is prevalent in UC admitted patients, with high rates of recurrence, this infection is related with higher rates of readmission and bigger need of colectomy during the first year.