Re-evaluating a vision-related quality of life questionnaire with item response theory (IRT) and differential item functioning (DIF) analyses

Background: For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT model, and investigates differential item functioning (DIF). Methods: Cross-sectional data were used from an observational study among visually-impaired patients (n = 296). Calibration was performed for every dimension of the LVQOL in the graded response model. Item goodness-of-fit was assessed with the S-X2-test. DIF was assessed on relevant background variables (i.e. age, gender, visual acuity, eye condition, rehabilitation type and administration type) with likelihood-ratio tests for DIF. The magnitude of DIF was interpreted by assessing the largest difference in expected scores between subgroups. Measurement precision was assessed by presenting test information curves; reliability with the index of subject separation. Results: All items of the LVQOL dimensions fitted the model. There was significant DIF on several items. For two items the maximum difference between expected scores exceeded one point, and DIF was found on multiple relevant background variables. Item 1 ‘Vision in general’ from the “Adjustment” dimension and item 24 ‘Using tools’ from the “Reading and fine work” dimension were removed. Test information was highest for the “Reading and fine work” dimension. Indices for subject separation ranged from 0.83 to 0.94. Conclusions: The items of the LVQOL showed satisfactory item fit to the graded response model; however, two items were removed because of DIF. The adapted LVQOL with 21 items is DIF-free and therefore seems highly appropriate for use in heterogeneous populations of visually impaired patients. (aut.ref.

Childhood Bladder and Bowel Dysfunction Questionnaire: Development, Feasibility, and Aspects of Validity and Reliability

Objectives: The aim of the study was to develop a questionnaire evaluating the frequency of symptoms over time of concomitant childhood bladder and bowel dysfunctions (CBBDs) in 5- to 12-year-old children and to assess its feasibility and aspects of validity and reliability. Methods: The Childhood Bladder and Bowel Dysfunction Questionnaire (CBBDQ) was developed in phases according to COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) in cooperation with epidemiologists, pediatricians, physiotherapists (phases 1 and 5), and professional translators (phase 5): selection of items (Delphi-method), content validity (pilot), feasibility (interviews), structural validity and internal consistency (field testing), and guideline-based translation (Dutch-English). Participants were parents of children, ages 5 to 12 years (phases 2-4). Results: Parents of 1333 children (mean age 7.8 years [standard deviation 2.1]) were included. Most common were urinary incontinence (35.9%), enuresis (29.7%), and constipation/fecal incontinence (30.1%). Concomitant CBBD was seen in 74.2% of 1229 children. Originally, a 27-item CBBDQ was developed. After the pilot (48 parents) a 23-item version remained for evaluation of feasibility aspects by interviewing 56 parents. Based on 1229 completed questionnaires during field testing, the CBBDQ reduced to 18 items. Cronbach a values were 0.74 and 0.71 for bladder and bowel subscales, respectively. Feasibility and aspects of validity and reliability were satisfactory. A definitive and accepted English version of the CBBDQ is available. Conclusions: When completed by parents, the 18-item evaluative CBBDQ appears feasible, content, and structurally valid with good internal consistency for the bladder and bowel subscales. The Dutch and English versions will be introduced clinically and subjected to further psychometric evaluatio

Antimicrobial and antiviral effect of High-Temperature Short-Time (HTST) pasteurization applied to human milk

In the United States, concerns over the transmission of infectious diseases have led to donor human milk generally being subjected to pasteurization prior to distribution and use. The standard method used by North American milk banks is Holder pasteurization (63 degrees C for 30 minutes). The authors undertook an experiment to validate the effects of a high-temperature short-time (HTST) pasteurization process (72 degrees C for 16 seconds) on the bioburden of human milk. It was concluded that HTST is effective in the elimination of bacteria as well as of certain important pathogenic viruse

Potential and limitation of UVC irradiation for the inactivation of pathogens in platelet concentrates

BACKGROUND: Pathogen contamination, causing transfusion-transmitted diseases, is an ongoing concern in transfusion of cellular blood products. In this explorative study, the pathogen-inactivating capacity of UVC irradiation in platelet (PLT) concentrates was investigated. The dose dependencies of inactivation of several viruses and bacteria were compared with the effect on PLT quality. STUDY DESIGN AND METHODS: The potential of UVC irradiation was studied with a range of lipid-enveloped (LE) and non-lipid-enveloped viruses (NLE) and bacteria. LE viruses were bovine viral diarrhea virus (BVDV), human immunodeficiency virus (HIV), pseudorabies virus (PRV), transmissible gastroenteritis virus (TGEV), and vesicular stomatitis virus (VSV). NLE viruses were canine parvovirus (CPV) and simian virus 40 (SV40). Bacteria were Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, and Bacillus cereus. After spiking and irradiation, samples were tested for residual infectivity and reduction factors (RFs) were calculated. Furthermore, the effect of UVC irradiation on PLT quality was determined by measuring in vitro quality variables. RESULTS: A UVC dose of 500 J per m(2) resulted in acceptable PLT quality (as measured by pH, lactate production, CD62P expression, and exposure of phosphatidylserine) and high RFs (>4 log) for CPV, TGEV, VSV, S. epidermidis, S. aureus, and E. coli. Intermediate RFs (approx. 3 log) were observed for BVDV, PRV, and B. cereus. Low RFs (approx. 1 log) were found for HIV and SV40. No differences in virus reduction were observed between cell-free and cell-associated virus. CONCLUSION: UVC irradiation is a promising pathogen-reducing technique in PLT concentrates, inactivating bacteria, and a broad range of viruses (with the exception of HIV) under conditions that have limited effects on PLT quality. Further optimization of the UVC procedure, however, is necessary to deal with blood-borne viruses like HI