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Vol. 40. Num. 4.October - December 2018
Pages 293-392
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Vol. 40. Num. 4.October - December 2018
Pages 293-392
Original article
DOI: 10.1016/j.htct.2018.03.006
Open Access
Blood Donation Knowledge Questionnaire (BDKQ-Brazil): analysis of items and application in primary healthcare users
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Miriane Lucindo Zucoloto
Corresponding author
mirianezucoloto@gmail.com

Corresponding author at: Department of Social Medicine, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP USP), Av. Bandeirantes, 3900, CEP: 14049-900, Monte Alegre, Ribeirão Preto, SP, Brazil.
, Edson Zangiacomi Martinez
Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP USP), Ribeirão Preto, SP, Brazil
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Tables (4)
Table 1. Answers to the Blood Donation Knowledge Questionnaire (BDKQ-Brazil) by 1055 primary healthcare users.
Table 2. Quality of items of BDKQ-Brazil according to facility and discrimination indexes obtained using classical test theory for the sample of primary healthcare users (n=1055).
Table 3. Distribution of answer to the BDKQ-Brazil of primary healthcare users according to sex and blood donation practice.
Table 4. Mean numbers of correct answers of primary healthcare users (n=1055) by sociodemographic and behavioral variables (BDKQ-Brazil).
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Abstract
Background

To present the results of the application of the Blood Donation Knowledge Questionnaire in a large and representative sample of users of primary care services in order to extend the evaluation of the metrics of the items and to assess knowledge about blood donation in association with sociodemographic variables.

Method

The Blood Donation Knowledge Questionnaire is composed of 24 items based on blood donation requirements of the Brazilian Ministry of Health and on some popular beliefs and concepts of the Brazilian population regarding the blood donation process. Data collection was carried out in 12 healthcare facilities of Ribeirão Preto, São Paulo. The analysis of items was performed using classical test theory with associations being assessed using the multivariate Tobit regression model.

Results

A total of 1055 individuals participated (79.7% females and a mean age of 40.6 years). Previous blood donation was reported by 246 (23.3%) participants, 669 (63.4%) had never donated, and 140 (13.3%) reported being ineligible to donate blood. This questionnaire is comprised of items considered easy-to-understand, with a facility level of medium to high and generally an adequate capability of discrimination. Higher means of correct answers were detected among females, individuals with more schooling, and subjects who had already donated blood.

Conclusion

The Blood Donation Knowledge Questionnaire is an instrument that aims to measure some general aspects of knowledge regarding blood donation and can be used in different contexts. There is evidence that knowledge of primary healthcare users regarding blood donation is correlated to sex, educational level, and previous blood donation.

Keywords:
Blood donation
Knowledge
Scales
Primary healthcare users
Blood donor beliefs
Full Text
Introduction

While the number of blood transfusions in Brazil is increasing by around 6% per year, the prevalence of voluntary blood donors in Brazil has stabilized1 with approximately 1.8% of the Brazilian population donating blood in recent years.1 This rate, however, is far from the goal of the World Health Organization (WHO) which is 3% of the donor population.2 Reasons for the lack of blood donors in low- to middle-income countries are multifactorial and despite efforts to understand the perceptions, motivation and obstacles about voluntary blood donation, little is known about these factors in the Brazilian context.3,4

Knowledge of the general population about donation is considered a determining factor in the decision to donate blood, in particular, in countries where this action is voluntary.5,6 On the other hand, lack of knowledge about eligibility criteria, the need for blood, and the general blood donation process such as donor safety, quality of service, place of collection, blood usage, together with countless popular beliefs and misconceptions about the donation process, contribute to the low prevalence of voluntary blood donors worldwide.5,7 According to Kumari and Raina,6 it is common for individuals with little knowledge about blood donation to rate themselves as ineligible to donate and this misperception can be perpetuated for many years, reducing the percentage of donors. In addition, greater knowledge of the population on this subject contributes to greater security during the process and the quality of the service, motivating new donors and increasing return rates of those already recruited.8

The assessment of knowledge about blood donation in the Brazilian general population is still incipient. In addition to the low number of studies with large representative samples, there is no specific instrument to ascertain this knowledge considering the specificities of blood donation in Brazil. Thus, our research group developed a 24-item scale named the Blood Donation Knowledge Questionnaire (BDKQ-Brazil)9 based on an instrument proposed by Renzaho and Polonsky.10 BDKQ-Brazil includes questions based on some popular beliefs and notions common to the Brazilian population. Its objective is to evaluate knowledge about the donation process according to blood donation specificities in Brazil based on the requirements of the Brazilian Ministry of Health and some popular beliefs and concepts regarding the donation of blood. BDKQ-Brazil was first published in 2016 in the Brazilian Journal of Hematology and Hemotherapy in the format of a letter to the editor along with its content validity.9 Subsequently, the scale was applied to a large and representative sample of users of primary healthcare services in the municipality of Ribeirão Preto, São Paulo; the results of which are presented herein.

The Brazilian primary healthcare system focuses on actions for health promotion and disease prevention. Thus, the main reason to perform this study at public healthcare facilities is that many of the users have frequent or regular appointments for basic routine clinical, physical, and laboratorial examinations and preventive visits.11 Hence, most users are commonly invited to participate in actions to prevent disease and promote health and we believe that many of them could be suitable to donate blood.

The objective of this study is to present the results of the application of BDKQ-Brazil in users of primary healthcare services thereby extending the evaluation of the metrics of the items when applied to a large representative sample, and assess knowledge about blood donation and possible associations with sociodemographic and behavioral characteristics.

MethodsStudy design, sampling and data collection

A cross-sectional study was conducted of 1055 primary healthcare users at 12 facilities from September 2015 to May 2016. Randomized stratified sampling was adopted. The study was conducted in Ribeirão Preto, which is the eighth largest municipality in São Paulo State with an estimated population of 682,302 in 2017. Ribeirão Preto is considered a technology center and has a high human development index compared to the rest of the country. In addition, the municipality is an important center for health, education, research, business tourism and culture.12

To obtain a representative sample of users of primary healthcare services, the 41 healthcare facilities of the municipality were grouped into 12 strata according to two factors: (1) the district in which they are located; (2) the Paulista Social Vulnerability Index (IPVS)13 prevalent in their area of coverage. The IPVS classifies the census tract sectors in six groups of social vulnerability (very high to low vulnerability) considering socioeconomic dimensions and the family life cycle. Thus, one healthcare facility was selected randomly within each stratum, totaling 12 healthcare facilities in which data collection was performed.

The sample size was calculated considering a confidence coefficient of 95% and an absolute precision of 3% for the estimation of the proportion of blood donors. The number of interviews in each healthcare facility was proportional to the respective population size and number of consultations per month with the total sample size estimated for this study being 1054 interviews.

Three trained interviewers were involved in data collection with the BDKQ-Brazil, a sociodemographic and behavioral questionnaire, and questions about previous donations being applied in a confidential face-to-face interview using paper forms. All potential participants were approached and invited to participate while they were waiting for medical consultations in the waiting rooms of healthcare facilities. The participants were informed about the objectives of the study, expected duration of the interview and the ethical aspects involved. The exclusion criteria adopted were related to age and mental/cognitive disability. Only over 18-year-old subjects, who did not present any impediment to answer the questions, participated in the study. Data were later entered in an online form by a trained member of the research staff with the database being revised routinely to avoid data entry errors.

Regarding blood donation, the participants were questioned about previous donations and ineligibility and were classified as ‘already donated’, ‘never donated’, or ‘unable to donate blood’ (self-declared). In addition, a questionnaire with sociodemographic questions including sex, age, marital status, socioeconomic class, educational level and self-perception of health was also applied. The participants were classified by socioeconomic levels – monthly family income (socioeconomic classes: A, B, C and D/E) and schooling (illiterate, elementary, middle school, high school, and higher education) according to the Brazilian Economic Classification Criteria (ABEP).14

Analysis of items of the BDKQ-Brazil and associations

The classification of the participants regarding performance in the instrument was conducted according to the Kelley15 proposal that considers the top 27% and the bottom 27% of the participants in the instrument to estimate the cut-off points. In the case of the BDKQ-Brazil (24 items), the cut-off points adopted for the classification of participants with the best and worst performances were ≥19 correct answers and ≤13 correct answers, respectively. The quality of items of the BDKQ-Brazil was assessed using classical test theory taking the difficulty and discrimination index as parameters.16 For the facility index, the degree of facility of items was estimated by the proportion of correct answers; each item can be classified as ‘very easy’ (proportion of right answers from 80 to 100%), ‘easy’ (60–80%), ‘average difficulty’ (40–60%), ‘difficult’ (20–40%) and ‘very difficult’ (0–20%). The discrimination index allows an analysis of how effectively each item can discriminate the respondents who had the best and the worst performances when answering the instrument. In other words, the greater the difference in the proportion of correct answers among the participants with the best and the worst performance, the greater the power of discrimination of the item. Results from 0 to 30% in the discrimination index represent a weak discrimination, from 30 to 60% a moderate discrimination and from 60 to 100% a strong discrimination.17 Thus, the purpose of this analysis is to identify easy items (most likely to be answered correctly) that have a high discriminatory power.

The answers of each item in the BDKQ-Brazil were analyzed according to sex and previous blood donation using the chi-square test. The analysis of associations considering sociodemographic/behavioral variables, previous blood donation and the means of correct answers of the instrument was performed using a multivariate Tobit regression model.18 The Tobit model is a regression model in which the dependent variable is truncated from below or above or both. In this case, the number of correct answers in the instrument is a variable ranging from 0 to 24. All analyses were performed using the SAS software, version 9.4 (SAS Institute).

Ethical considerations

This study was approved by the Ethics Committee on Human Research of the Hospital das Clínicas in Ribeirão Preto (CAAE: 38148814.2.0000.5440), and data collection in health facilities was approved by the Ribeirão Preto Municipal Health Department. Only adult individuals (≥18 years) who agreed and signed informed consent forms participated in the study. The questionnaires were stored separately from the informed consent terms to ensure participants’ anonymity during data processing.

Results

A total of 1055 primary healthcare users (80.7% of the total invited) answered all the questions of the questionnaire and were included in the study. The sample was composed of 841 (79.7%) females with a mean age of 45.1 years [standard deviation (SD): 15.3] and 214 (20.3%) males with a mean age of 39.5 years (SD: 14.9). Of the participants, 669 (63.4%) had never donated blood, 246 (23.3%) had already donated blood, and 140 (13.3%) declared themselves unable to donate blood.

Table 1 shows the study participants’ answers of the BDKQ-Brazil. The vast majority of the participants (n=1003; 97.9%) replied that people do no pay to receive blood transfusions, 986 (93.5%) answered that all donated blood is tested for infectious diseases and only 607 (57.5%) declared to be aware of their blood type. In addition, a large number of participants (56.3%) stated that they did not know how much blood is taken in each blood donation and 38.0% did not know how long the blood donation process takes.

Table 1.

Answers to the Blood Donation Knowledge Questionnaire (BDKQ-Brazil) by 1055 primary healthcare users.

  English  Answersa  Total
      n 
1Do you know your blood type?No  448  42.5 
Yes  607  57.5 
2In order to be able to donate blood, what is the minimum weight that a person needs to have?40kg  61  5.8 
50kg  516  48.9 
60kg  251  23.8 
I don’t know  227  21.5 
3Is all donated blood tested in order to verify if it has any disease that can be transmitted to others?No  69  6.5 
Yes  986  93.5 
4Can under 16-years-old individuals donate blood?No  854  81.0 
Yes  100  9.5 
I don’t know  100  9.5 
5Can pregnant women donate blood?No  806  76.4 
Yes  48  4.5 
I don’t know  201  19.1 
6Can a person who has diabetes or high blood pressure donate blood?No  937  88.8 
Yes  23  2.2 
I don’t know  95  9.0 
7Can a person who has or has had any type of cancer donate blood?No  895  84.8 
Yes  22  2.1 
I don’t know  138  13.1 
8Can women who are menstruating donate blood?No  401  38.1 
Yes  330  31.3 
I don’t know  323  30.6 
9Is there a maximum age for blood donation?No  205  19.4 
Yes  651  61.7 
I don’t know  199  18.9 
10Can women who are breastfeeding donate blood?No  504  47.8 
Yes  285  27.0 
I don’t know  266  25.2 
11Is the blood from only one donor enough for one person who needs blood?No  740  70.2 
Yes  204  19.3 
I don’t know  111  10.5 
12When people need to receive blood, do they have to pay?No  1033  97.9 
Yes  22  2.1 
I don’t know  –  – 
13Does donated blood have to be used within 24h after donation, otherwise it is not good
anymore?
No  745  70.7 
Yes  117  11.1 
I don’t know  191  18.1 
14Can a person acquire a disease by donating blood?No  749  71.0 
Yes  251  23.8 
I don’t know  55  5.2 
15If the blood donor is male, can he donate every 2 months, and can women donate every 3 months.No  215  20.4 
Yes  498  47.2 
I don’t know  342  32.4 
16In Brazil, is it allowed by law to pay a person to donate blood?No  971  92.0 
Yes  23  2.2 
I don’t know  61  5.6 
17When someone donates blood, does the amount of blood in the human body return to what it was
before within 24–48h?
No  58  5.5 
Yes  834  79.1 
I don’t know  163  15.4 
18If a donor has a fever on the day of donation, can he donate blood?No  828  78.5 
Yes  61  5.8 
I don’t know  166  15.7 
19Does donating blood make you lose or gain weight?Lose weight  11  1.0 
Gain weight  13  1.2 
Neither  975  92.4 
I don’t know  56  5.3 
20The capacity of a little coffee cup is 50mL. When a person donates blood, the equivalent to how many coffee cups are taken?2–4  49  4.6 
5–8  92  8.7 
9–10  202  19.2 
11–20  118  11.2 
I don’t know  594  56.3 
21After a person enters in the donation room to donate blood, how long is the blood donation process?20min  372  35.3 
40m to 1254  24.1 
More than 128  2.6 
I don’t know  401  38.0 
22In order to donate blood, should the donor be fasting?No  487  46.2 
Yes  106  10.1 
I don’t know  460  43.7 
23Can smokers donate blood?
No  290  27.5 
Yes  587  55.7 
I don’t know  177  16.8 
24Does donating blood thicken or thin the blood?Thin  87  8.3 
Thicken  79  7.5 
Neither  745  70.6 
I don’t know  143  13.6 
a

The correct answer for each question is highlighted in bold type.

The quality of items of the BDKQ-Brazil according to facility and discrimination indices obtained in classical test theory are shown in Table 2. Items 5, 9, 13, 14, 17, 18, and 24 were distinguished by the two indices as easy to very easy results with a power of discrimination from moderate to strong.

Table 2.

Quality of items of BDKQ-Brazil according to facility and discrimination indexes obtained using classical test theory for the sample of primary healthcare users (n=1055).

Item  Worst (%)  Best (%)  Discrimination index (%)  Facility index (%) 
34.08  80.71  46.63a  57.54 
20.6  76.4  55.80a  48.91 
85.77  98.21  12.44  93.46a 
64.79  92.14  27.35  80.95a 
55.43  88.21  32.78a  76.4a 
82.77  93.21  10.44  88.82a 
77.15  92.5  15.35  84.83a 
13.48  48.57  35.09a  31.28 
39.33  77.86  38.53a  61.71a 
10  28.46  68.21  39.75a  47.77 
11  13.11  26.43  13.32  19.34 
12  95.88  99.64  3.76  97.90a 
13  43.45  91.79  48.34a  70.62a 
14  55.81  86.07  30.26a  71.00a 
15  23.6  74.29  50.69a  47.2 
16  82.77  98.57  15.8  92.04a 
17  52.81  92.5  39.69a  79.05a 
18  61.42  91.79  30.37a  78.48a 
19  79.4  98.93  19.53  92.42a 
20  6.74  36.79  30.05a  19.15 
21  11.99  61.43  49.44a  35.26 
22  18.35  76.79  58.44a  46.16 
23  31.46  78.57  47.11a  55.64 
24  47.19  93.21  46.02a  70.62a 
a

Items with higher discrimination and/or facility index. The best items were those classified as “easy or very easy” in the facility index (cutoff point ≥60), and with a discrimination power classified as moderate to high (cutoff point ≥30).

The distribution of answers of the primary healthcare users varied depending on sex and previous blood donations (Table 3). A higher frequency of correct answers to questions such as blood type, donor weight, blood donation during the menstrual period, disease acquired from blood donation, and payment to receive blood transfusion was observed among females. On the other hand, men tended to have a higher frequency of correct answers to the questions evaluating the amount of blood donated, duration of the blood collection process and blood donation by smokers. Participants who had already donated blood had a higher frequency of correct answers to the questions evaluating blood type, minimum weight, time interval between donations, weight gain or loss with blood donation, volume of donated blood, time spent for blood donation, fasting before donation, and thickness or thinness of the blood after donation. The participants who described themselves as unable to donate blood had a higher frequency of correct answers to the question of maximum donation age. Finally, among those who never donated blood, the frequency of correct answers on acquiring disease from blood donation was higher.

Table 3.

Distribution of answer to the BDKQ-Brazil of primary healthcare users according to sex and blood donation practice.

  Item/subject  Answersa  FemalesMalesp  Never donatedUnable to donateAlready donatedp 
      n  n    n  n  n   
1Blood typeNo  337  40.1  111  51.9  <0.01324  48.4  65  46.4  59  24.0  <0.01
Yes  504  59.9  103  48.1  345  51.6  75  53.6  187  76.0 
2Weight40kg  44  5.2  17  7.9  0.0430  4.5  10  7.1  21  8.5  <0.01
50kg  429  51.0  87  10.7  308  46.0  65  46.4  143  58.1 
60kg  193  23.0  58  27.1  145  21.7  45  32.1  61  24.8 
I don’t know  175  20.8  52  24.3  186  27.8  20  14.3  21  8.5 
3Blood testsNo  55  6.5  14  6.5  0.9952  7.8  4.3  11  4.5  0.10
Yes  786  93.5  200  93.5  617  92.2  134  95.7  235  95.5 
4Minimum age for donationNo  684  81.4  170  79.4  0.80550  82.4  108  77.2  196  79.7  0.07
Yes  78  9.3  22  10.3  51  7.6  17  12.1  32  13.0 
I don’t know  78  9.3  22  10.3  67  10.0  15  10.7  18  7.3 
5PregnancyNo  650  77.3  156  72.9  0.13505  75.5  110  78.6  191  77.6  0.79
Yes  33  3.9  15  7.0  32  4.8  2.9  12  4.9 
I don’t know  158  18.8  43  20.1  132  19.7  26  18.6  43  17.5 
6Diabetes and high blood pressureNo  752  89.4  185  86.4  0.35594  88.8  123  87.9  220  89.4  0.51
Yes  16  1.9  3.3  15  2.2  0.7  2.9 
I don’t know  73  8.7  22  10.3  60  9.0  16  11.4  19  7.7 
7CancerNo  719  85.5  176  82.2  0.45576  86.1  122  87.2  197  80.1  0.14
Yes  16  1.9  2.8  13  1.9  0.7  3.2 
I don’t know  106  12.6  32  15.0  80  12.0  17  12.1  41  16.7 
8MenstruationNo  287  34.2  114  53.3  <0.01253  37.9  52  37.2  96  39.0  0.54
Yes  291  34.6  39  18.2  210  31.4  38  27.1  82  33.3 
I don’t know  262  31.2  61  28.5  205  30.7  50  35.7  68  27.7 
9Maximum age for donationNo  169  20.1  36  16.8  0.12138  20.6  20  14.3  47  19.1  <0.01
Yes  506  60.2  145  67.8  382  57.1  103  73.6  166  67.5 
I don’t know  166  19.7  33  15.4  149  22.3  17  12.1  33  13.4 
10Breast-feedingNo  414  49.2  90  42.1  0.17299  44.7  74  52.9  131  53.2  0.07
Yes  222  26.4  63  29.4  189  28.2  31  22.1  65  26.4 
I don’t know  205  24.4  61  28.5  181  27.1  35  25.0  50  20.3 
11Volume demandNo  585  69.6  155  72.4  0.70464  69.4  94  67.1  182  74.0  0.44
Yes  165  19.6  39  18.2  133  19.9  27  19.3  44  17.9 
I don’t know  91  10.8  20  9.4  72  10.8  19  13.6  20  8.1 
12Pay for transfusionNo  825  98.1  208  97.2  0.41654  97.8  138  98.6  241  98.0  0.83
Yes  16  1.9  2.8  15  2.2  1.4  2.0 
13Blood durabilityNo  587  70.0  158  73.8  0.17459  68.7  99  70.7  187  76.3  0.21
Yes  101  12.0  16  7.5  81  12.1  13  9.3  23  9.4 
I don’t know  151  18.0  40  18.7  128  19.2  28  20.0  35  14.3 
14Acquire disease in blood donationNo  619  73.6  130  60.8  <0.01494  73.9  89  63.6  166  67.5  <0.01
Yes  176  20.9  75  35.0  134  20.0  46  32.9  71  28.9 
I don’t know  46  5.5  4.2  41  6.1  3.5  3.6 
15Period between donationsNo  167  19.9  48  22.4  0.09133  19.9  25  17.8  57  23.2  <0.01
Yes  388  46.1  110  51.4  278  41.5  74  52.9  146  59.3 
I don’t know  286  34.0  56  26.2  258  38.6  41  29.3  43  17.5 
16Payment for blood donorsNo  784  93.2  187  87.4  <0.01610  91.2  130  92.8  231  93.9  0.15
Yes  11  1.3  12  5.6  12  1.8  3.6  2.4 
I don’t know  46  5.5  15  7.0  47  7.0  3.6  3.7 
17Blood volume replacementNo  39  4.6  19  8.9  0.0531  4.6  5.0  20  8.1  <0.01
Yes  669  79.6  165  77.1  520  77.7  107  76.4  207  84.2 
I don’t know  133  15.8  30  14.0  118  17.6  26  18.6  19  7.7 
18FeverNo  662  78.7  166  77.6  0.94521  77.9  111  79.3  196  79.7  0.69
Yes  48  5.7  13  6.1  38  5.7  4.3  17  6.9 
I don’t know  131  15.6  25  16.3  110  16.4  23  16.4  33  13.4 
19Gain or lose weightLose weight  0.8  1.9  0.051.2  2.1  0.03
Gain weight  0.8  2.8  1.0  1.4  1.6 
Neither  784  93.3  191  89.2  608  90.9  131  93.6  236  95.9 
I don’t know  43  5.1  13  6.1  46  6.9  2.9  2.4 
20Volume of blood donated2–4  37  4.4  12  5.6  <0.0134  5.1  2.1  12  4.9  <0.01
5–8  66  7.8  26  12.1  39  5.8  12  8.6  41  16.7 
9–10  152  18.1  50  23.4  84  12.6  26  18.6  92  37.4 
11–20  84  10.0  34  15.9  72  10.8  14  10.0  32  13.0 
I don’t know  502  56.7  92  43.0  440  65.8  85  60.7  69  28.0 
21Time spent during donation20min  262  31.1  110  51.4  <0.01160  23.9  40  28.6  172  69.9  <0.01
40m to 1 hour  214  25.5  40  18.7  176  26.3  31  22.1  47  19.1 
More than 125  3.0  1.4  22  3.3  2.9  0.8 
I don’t know  340  40.4  61  28.5  311  46.5  65  46.4  25  10.2 
22Fasting before donationNo  399  47.5  88  41.3  0.09265  39.6  65  46.4  157  64.3  <0.01
Yes  88  10.5  18  8.5  318  47.5  61  43.6  81  33.2 
I don’t know  353  42.0  107  50.2  86  12.9  14  10.0  2.5 
23Smokers and blood donationNo  248  29.5  42  19.6  <0.01223  33.4  35  25.0  32  13.0  <0.01
Yes  439  52.3  148  69.2  330  49.4  77  55.0  180  73.2 
I don’t know  153  18.2  24  11.2  115  17.2  28  20.0  34  13.8 
24Thicken or thin the bloodThin  66  7.9  21  9.8  0.7255  8.2  17  12.1  15  6.1  <0.01
Thicken  61  7.2  18  8.4  48  7.2  10  7.1  21  8.5 
Neither  599  71.3  146  68.2  451  67.5  101  72.2  193  78.5 
I don’t know  114  13.6  29  13.6  114  17.1  12  8.6  17  6.9 
a

The correct answer for each question is highlighted in bold type.

The study of associations considering the mean numbers of correct answers in the BDKQ-Brazil and sociodemographic and behavioral variables are presented in Table 4. Differences in mean numbers were associated with sex, educational level and previous blood donations. Females, study participants with more schooling and those who had already donated blood presented higher numbers of correct answers. No associations of mean numbers of correct answers were found for marital status, socioeconomic class, age group and self-perception of health.

Table 4.

Mean numbers of correct answers of primary healthcare users (n=1055) by sociodemographic and behavioral variables (BDKQ-Brazil).

Variable  Categories  n  Correct answers
      Mean  Standard deviation  Minimum–maximum  p-value (a) 
SexFemale  841  15.5  3.2  4–23  <0.01 
Male  214  15.2  3.3  3–22  Ref. 
Marital statusMarried  648  15.5  3.2  4–23  0.14 
Divorced  107  15.7  2.7  8–22  0.21 
Single  247  15.4  3.3  3–23  0.26 
Widowed  53  14.5  3.1  8–22  Ref. 
Socioeconomic classaA or B1  65  16.1  3.5  4–22  0.35 
B2  290  16.0  3.1  4–23  0.13 
C1  368  15.5  3.2  3–23  0.28 
C2  235  15.0  3.4  4–22  0.66 
D or E  97  14.3  2.6  7–21  Ref. 
Age groups (years)Under 25  188  14.9  3.3  3–22  0.27 
26–30  132  15.3  3.3  4–21  0.84 
31–40  250  15.9  3.0  8–23  0.26 
41–50  173  15.7  3.2  8–22  0.18 
51–60  164  15.8  3.4  4–23  0.08 
>60  148  15.0  2.9  6–22  Ref. 

Educational levelb
Illiterate  130  14.2  3.0  5–22  <0.01 
Elementary school  61  14.3  2.9  6–20  <0.01 
Middle school  221  15.2  3.4  4–23  <0.01 
High school  517  15.7  3.1  3–23  0.02 
Higher education  126  16.8  3.0  9–22  Ref. 

Self-perception of health
Good  735  15.6  3.2  3–23  0.07 
Regular  280  15.1  3.3  4–23  0.27 
Poor  40  14.7  3.1  8–20  Ref. 
Blood donation practiceNever donated  669  14.9  3.2  3–23  <0.01 
Unable to donate  140  15.5  3.0  8–22  <0.01 
Already donated  246  17.1  2.9  6–23  Ref. 

(a) Multivariate Tobit regression model.

a

A/B1 (R$ 15,071.00 or USD 4739.00); B2 (R$ 4852.00 or USD 1526.00); C1 (R$ 2705.00 or USD 851.00); C2 (R$1625.00 or USD 511.00); D or E (R$ 728.00 or USD 229.00).

b

Elementary school (preschool to 4th grade); middle school (5th grade to 8th grade); high school (secondary education – 3 years).

Discussion

The BDQK-Brazil is an original instrument that aims to measure and validate general blood donation knowledge among primary healthcare users.9 The results of this study show that the instrument is comprised of easy-to-understand questions with an adequate discrimination capability, which suggests that it can be used in many settings, including for donors and non-donors, and in different social and educational levels. Higher mean numbers of correct answers were associated with being female, having a higher educational level and previously donating blood.

Higher mean numbers of correct answers were observed among participants who had already donated blood. Donors presented greater knowledge on the blood donation process and lower mean numbers for answers about misconceptions compared to non-donors. It was expected that blood donors would present better knowledge regarding blood donation compared to non-donors,8 and the results of this study have provided evidence for this. If this had not happened, the discrimination power of the BDKQ-Brazil would have been dubious.

Although a higher prevalence of males among blood donors is characteristic in Brazil,3,19 females presented higher mean numbers of correct answers in this study. However, it can be observed that women had more correct answers for questions related to health and general knowledge such as blood type, donor weight, blood donation during menstrual, acquiring disease from blood donation and payment to receive blood. On the other hand, male donors had more correct answers for questions related to the blood donation process and eligibility, such as the volume of blood donated, the duration of the blood donation process and the eligibility of smokers. The results of this study corroborate the concept that blood donors have more knowledge about the donation process.5,20 Previous studies in the Brazilian population showed that individuals with high educational levels are more likely to donate blood,4,21,22 which justifies the number of correct answers according to the educational level of the participants.

In the current sample, levels of blood donation knowledge varied from moderate to high; most items were answered correctly by many participants. However, nearly one third of the study participants incorrectly answered the item on acquiring disease through blood donation. This information as well as other common misconceptions observed in this study are very important and should be discussed in respect to donor recruitment strategies in future campaigns promoted by blood banks.

A limitation of this study is regarding the higher number of women in the sample of primary healthcare users. However, this is a characteristic of the population who seek healthcare services in Brazil.23 Although, in this study the rate of women was higher than expected, we understand that this is an important opportunity to increase knowledge about blood donation among individuals who have never been to a blood bank, an under-studied population in the field of transfusion epidemiology.

The BDKQ-Brazil is an original instrument that aims to measure general aspects of knowledge about blood donation that can be used in many contexts. There is evidence that greater knowledge regarding blood donation is associated with sex, educational level and previous blood donation in primary healthcare users. We strongly suggest that BDKQ-Brazil should be applied aiming to improve the instrument and its adaptation for distinct populations, as well as to fill the gap in the scientific literature in the field of blood donation epidemiology.

Financial support

This study was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) under grant # 2014/14020-6 and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Conflicts of interest

The authors declare no conflicts of interest.

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Copyright © 2018. Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular
Idiomas
Hematology, Transfusion and Cell Therapy

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