Development of a questionnaire to assess knowledge regarding blood donation in a Brazilian population

Comprehensive studies on the knowledge and attitude toward blood donation, considering cultural differences and traditions , are useful for planning strategies in the recruitment of non-remunerated blood donors. Several instruments to assess knowledge regarding blood donation have been presented in the scientific literature 1,2 such as the instrument proposed by Sabu et al. 3 These authors introduced a questionnaire in which the knowledge of blood donation among health sciences students was measured using 12 questions based on the benefits of blood donation, general requirements to become an eligible donor and medical conditions and diseases that restrict blood donation. We developed a 24-item multiple-choice questionnaire, taking into account the speci-ficities of the Brazilian population. This questionnaire was based on some items of the instrument developed by Renzaho and Polonsky 4 and on the Brazilian legislation regarding blood donation. Named the " Brazilian blood donation knowledge questionnaire " (BDKQ-Brazil), it can be completed by donors if they are literate or administered via interview. It is believed that the BDKQ-Brazil applies to a broad range of population groups. The content validity of the proposed questionnaire was evaluated by computing a content validity ratio (CVR) 5 based on experts' ratings of item relevance. A convenience sample of twenty professionals (four men and sixteen women) who were participating in the Master's Course in Hemother-apy and Biotechnology of the Universidade de São Paulo (USP) in Ribeirão Preto was used for evaluation. All participants were informed of the purpose of the research before signing an informed consent form. All these experts completed a healthcare undergraduate course and have professional activities in hematology services or blood donation centers Preto and Rio de Janeiro). The mean age of the participants was 36.1 years (range: 27–56 years) and the mean length of professional experience was 10.7 years (range: 3–30 years). The experts were asked to classify each item on the questionnaire as 'essential', 'useful but not essential', and 'not necessary'. For each item, the CVR is given by (E − n/2)/(n/2), where n is the total number of experts and E is the number of experts indicating 'essential'. The CVR ranges between −1 and 1. When less than half of the experts rated the item as 'essential', the value of CVR was negative. According to Wilson et al., 6 when n = 20 and the CVR is greater than or equal to 0.368, there is evidence that the respective item …