Introduction/objectivesLarge scale population-based studies focusing on infectious diseases are scarce. This may be explained by methodological obstacles concerning ascertainment of data on infectious diseases requiring, e.g. collection of data on relatively short-termed symptoms and/or collection of biosamples for pathogen identification during a narrow time window. In the German National Cohort (GNC), a novel self-administered questionnaire will be used in addition to biosampling to collect data on selected infectious diseases and symptoms. The aim of this study was to evaluate in Pretest 2 of the GNC newly added items on self-assessed vulnerability to several infectious diseases and to assess test–retest reliability of the questionnaire.MethodsThe study was conducted in two study centres (Hamburg and Hanover) during Pretest 2 of the GNC. A self-administered paper questionnaire was applied. In Hamburg, participants were asked to fill in the questionnaire during their regular visit at the study centre. For test–retest reliability, participants in Hanover filled in the same questionnaire at home twice. To evaluate agreement, item-related percentage agreement and kappa (κ) were calculated. In addition, we computed Bennet’s S and Krippendorf’s alpha (α). Items on self-assessed vulnerability to infections were evaluated by comparing them with the corresponding self-reported frequency of infections. An explanatory factor analysis was applied to construct the scores of self-reported infection frequency and self-assessed vulnerability to infections.ResultsThe evaluation of the internal consistency of the five-item instrument of self-assessed vulnerability to infections resulted in a Cronbach’s α of 0.78. The factor analysis yielded evidence of one factor. The factor was divided into three groups (lowest quintile classified as “less prone to infections” compared to peers; second, middle and fourth quintiles classified as “similarly prone to infections” and highest quintile classified as “more prone to infections”). Participants classified as “less prone to infections” reported fewer infections than participants classified as “more prone to infections”. Spearman’s correlation of the two scores (self-reported infection frequency and self-assessed vulnerability to infection) was 0.50 (p < 0.0001). For quantifying reliability, 88 participants with a median time of 8 days between filling in both questionnaires could be included in the analysis; for items sensitive to disease occurrence between both questionnaires only participants with no relevant disease in this time interval were included (n = 75). The weighted κ ranged between 0.65 and 0.87 for the items on infectious disease frequency in the last 12 months, for items on symptom frequency in the past 12 months between 0.77 and 0.90, and for items on vulnerability compared to peers between 0.68 and 0.76.ConclusionA five-item instrument on self-assessed vulnerability to infections seems to be promising, but requires further evaluation. Overall, the questionnaire on self-rep...

This study aimed to evaluate feasibility, acceptability, reliability, and validity of the existing four‐item Shared Decision Making (SDM) Process Scale for use in evaluating genetic testing decisions. Patients from a large hereditary cancer genetics practice were invited to participate in a two‐part survey after completing pre‐test genetic counseling. The online survey included the SDM Process Scale and the SURE scale, a measure of decisional conflict. SDM Process scores were compared to SURE scores to test convergent validity, and respondents were sent a second survey 1 week later to assess retest reliability. The response rate was 65% (n = 259/398) and missing data was low (<1%). SDM scores ranged from zero to four with a mean of 2.3 (SD = 1.1). Retest reliability was good, with intraclass correlation of 0.84, 95% confidence interval (0.79, 0.88). No relationship was found between SDM Process scores and decisional conflict (p = 0.46), likely because 85% of participants reported no decisional conflict. The four‐item SDM Process Scale demonstrated feasibility, acceptability, and retest reliability, but not convergent validity with decisional conflict. These findings provide initial evidence for use of this scale to measure patient perceptions of SDM in pre‐test counseling for hereditary cancer genetic testing.