Measuring through questionnaires : Rasch analysis as a tool for keeping the same meaning across different patients

Whole-person variables may describe behaviours, perceptions, knowledges, attitudes. These are the outcomes of the most various health-care interventions. Such variables can only be observed through samples of representatives behaviours (items in questionnaires). The amount of the variables is usually inferred through counts of the scores arbitrarily assigned to the various items. Rasch Analysis (RA) is a novel statistical method allowing the estimate of true linear measures of item difficulty and subject ability subtended by raw counts. This also allows the estimate of stability of the items hierarchy (which item is more difficult, which is less) across time, raters and diagnostic or cultural subgroups. If this hierarchy is unstable (Differential Item Functioning \u2013 DIF) the same questionnaire actually depicts qualitatively distinct, non comparable, conditions. RA may help to either detect the problem, or re-calibrate the subject measures by accounting for DIF. This may warrant real metric equivalence across medical questionnaires applied to different diagnostic groups and/or different linguistic/cultural contests, thus fostering multicentric, international trials

Profile of Toll-Like Receptors on Peripheral Blood Cells in Relation to Acute Graft-versus-Host Disease after Allogeneic Stem Cell Transplantation

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Sequential monitoring of lymphocyte subsets and of T-and-B cell neogenesis indexes to identify time-varying immunologic profiles in relation to graft-versus-host disease and relapse after allogeneic stem cell transplantation

T and B lymphocyte subsets have been not univocally associated to Graft-versus-host disease (GVHD) and relapse of hematological alignancies after stem cell transplantation (SCT). Their sequential assessment together with B and T cell neogenesis indexes has been not thoroughly analysed in relation to these changing and interrelated immunologic/clinic events yet. Lymphocyte subsets in peripheral blood (PB) and B and T cell neogenesis indexes were analysed together at different time points in a prospective study of 50 patients. Principal component analysis (PCA) was used as first step of multivariate analysis to address issues related to a high number of variables versus a relatively low number of patients. Multivariate analysis was completed by Fine-Gray proportional hazard regression model. PCA identified 3 clusters of variables (PC1-3), which correlated with acute GVHD: PC1 (pre-SCT: KRECs 656608/ml, unswitched memory B 44%, CD8+TCM cells>4%; HR 1.9, p = 0.01), and PC3 (at aGVHD onset: CD4+TEMRA69%, switched memory CD19+ = 0 cells and KRECs<6614/ml at +90; HR 0.1, p = 0.008). All these immunologic parameters were independent indicators of chronic GVHD and relapse, also considering the possible effect of previous steroid-therapy for acute GVHD. Specific time-varying immunologic profiles were associated to GVHD and relapse. Pre-SCT host immune-microenvironment and changes of B cell homeostasis could influence GVH- and Graft-versus-Tumor reactions. The paradoxical increase of EM Treg in PB of patients with GVHD could be explained by their compartmentalization outside lymphoid tissues, which are of critical relevance for regulation of GVH reactions