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Hematology, Transfusion and Cell Therapy

Print version ISSN 2531-1379On-line version ISSN 2531-1387

Hematol., Transfus. Cell Ther. vol.40 no.4 São Paulo Oct./Dec. 2018

http://dx.doi.org/10.1016/j.htct.2018.03.006 

Original Articles

Blood Donation Knowledge Questionnaire (BDKQ-Brazil): analysis of items and application in primary healthcare users

Miriane Lucindo Zucoloto*  1 

Edson Zangiacomi Martinez1 

1Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP USP), Ribeirão Preto, SP, Brazil


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

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.

Methods

Study 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 %
1 Do you know your blood type? No 448 42.5
Yes 607 57.5
2 In order to be able to donate blood, what is the minimum weight that a person needs to have? 40 kg 61 5.8
50 kg 516 48.9
60 kg 251 23.8
I don’t know 227 21.5
3 Is 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
4 Can under 16-years-old individuals donate blood? No 854 81.0
Yes 100 9.5
I don’t know 100 9.5
5 Can pregnant women donate blood? No 806 76.4
Yes 48 4.5
I don’t know 201 19.1
6 Can 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
7 Can 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
8 Can women who are menstruating donate blood? No 401 38.1
Yes 330 31.3
I don’t know 323 30.6
9 Is there a maximum age for blood donation? No 205 19.4
Yes 651 61.7
I don’t know 199 18.9
10 Can women who are breastfeeding donate blood? No 504 47.8
Yes 285 27.0
I don’t know 266 25.2
11 Is 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
12 When people need to receive blood, do they have to pay? No 1033 97.9
Yes 22 2.1
I don’t know - -
13 Does donated blood have to be used within 24 h after donation, otherwise it is not good anymore? No 745 70.7
Yes 117 11.1
I don’t know 191 18.1
14 Can a person acquire a disease by donating blood? No 749 71.0
Yes 251 23.8
I don’t know 55 5.2
15 If 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
16 In 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
17 When someone donates blood, does the amount of blood in the human body return to what it was before within 24-48 h? No 58 5.5
Yes 834 79.1
I don’t know 163 15.4
18 If 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
19 Does 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
20 The capacity of a little coffee cup is 50 mL. 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
21 After a person enters in the donation room to donate blood, how long is the blood donation process? 20 min 372 35.3
40 m to 1 h 254 24.1
More than 1 h 28 2.6
I don’t know 401 38.0
22 In order to donate blood, should the donor be fasting? No 487 46.2
Yes 106 10.1
I don’t know 460 43.7
23 Can smokers donate blood? No 290 27.5
Yes 587 55.7
I don’t know 177 16.8
24 Does 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

aThe 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 (%)
1 34.08 80.71 46.63a 57.54
2 20.6 76.4 55.80a 48.91
3 85.77 98.21 12.44 93.46a
4 64.79 92.14 27.35 80.95a
5 55.43 88.21 32.78a 76.4a
6 82.77 93.21 10.44 88.82a
7 77.15 92.5 15.35 84.83a
8 13.48 48.57 35.09a 31.28
9 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

aItems 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 Females Males p Never donated Unable to donate Already donated p
n % n % n % n % n %
1 Blood type No 337 40.1 111 51.9 <0.01 324 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
2 Weight 40 kg 44 5.2 17 7.9 0.04 30 4.5 10 7.1 21 8.5 <0.01
50 kg 429 51.0 87 10.7 308 46.0 65 46.4 143 58.1
60 kg 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
3 Blood tests No 55 6.5 14 6.5 0.99 52 7.8 6 4.3 11 4.5 0.10
Yes 786 93.5 200 93.5 617 92.2 134 95.7 235 95.5
4 Minimum age for donation No 684 81.4 170 79.4 0.80 550 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
5 Pregnancy No 650 77.3 156 72.9 0.13 505 75.5 110 78.6 191 77.6 0.79
Yes 33 3.9 15 7.0 32 4.8 4 2.9 12 4.9
I don’t know 158 18.8 43 20.1 132 19.7 26 18.6 43 17.5
6 Diabetes and high blood pressure No 752 89.4 185 86.4 0.35 594 88.8 123 87.9 220 89.4 0.51
Yes 16 1.9 7 3.3 15 2.2 1 0.7 7 2.9
I don’t know 73 8.7 22 10.3 60 9.0 16 11.4 19 7.7
7 Cancer No 719 85.5 176 82.2 0.45 576 86.1 122 87.2 197 80.1 0.14
Yes 16 1.9 6 2.8 13 1.9 1 0.7 8 3.2
I don’t know 106 12.6 32 15.0 80 12.0 17 12.1 41 16.7
8 Menstruation No 287 34.2 114 53.3 <0.01 253 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
9 Maximum age for donation No 169 20.1 36 16.8 0.12 138 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
10 Breast-feeding No 414 49.2 90 42.1 0.17 299 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
11 Volume demand No 585 69.6 155 72.4 0.70 464 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
12 Pay for transfusion No 825 98.1 208 97.2 0.41 654 97.8 138 98.6 241 98.0 0.83
Yes 16 1.9 6 2.8 15 2.2 2 1.4 5 2.0
13 Blood durability No 587 70.0 158 73.8 0.17 459 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
14 Acquire disease in blood donation No 619 73.6 130 60.8 <0.01 494 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 9 4.2 41 6.1 5 3.5 9 3.6
15 Period between donations No 167 19.9 48 22.4 0.09 133 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
16 Payment for blood donors No 784 93.2 187 87.4 <0.01 610 91.2 130 92.8 231 93.9 0.15
Yes 11 1.3 12 5.6 12 1.8 5 3.6 6 2.4
I don’t know 46 5.5 15 7.0 47 7.0 5 3.6 9 3.7
17 Blood volume replacement No 39 4.6 19 8.9 0.05 31 4.6 7 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
18 Fever No 662 78.7 166 77.6 0.94 521 77.9 111 79.3 196 79.7 0.69
Yes 48 5.7 13 6.1 38 5.7 6 4.3 17 6.9
I don’t know 131 15.6 25 16.3 110 16.4 23 16.4 33 13.4
19 Gain or lose weight Lose weight 7 0.8 4 1.9 0.05 8 1.2 3 2.1 0 - 0.03
Gain weight 7 0.8 6 2.8 7 1.0 2 1.4 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 4 2.9 6 2.4
20 Volume of blood donated 2-4 37 4.4 12 5.6 <0.01 34 5.1 3 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
21 Time spent during donation 20 min 262 31.1 110 51.4 <0.01 160 23.9 40 28.6 172 69.9 <0.01
40 m to 1 hour 214 25.5 40 18.7 176 26.3 31 22.1 47 19.1
More than 1 h 25 3.0 3 1.4 22 3.3 4 2.9 2 0.8
I don’t know 340 40.4 61 28.5 311 46.5 65 46.4 25 10.2
22 Fasting before donation No 399 47.5 88 41.3 0.09 265 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 6 2.5
23 Smokers and blood donation No 248 29.5 42 19.6 <0.01 223 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
24 Thicken or thin the blood Thin 66 7.9 21 9.8 0.72 55 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

aThe 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)
Sex Female 841 15.5 3.2 4-23 <0.01
Male 214 15.2 3.3 3-22 Ref.
Marital status Married 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 classa A 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 practice Never 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.

aA/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).

bElementary 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).

References

1 Health BMo. Caderno de informação: sangue e hemoderivados: dados de 2014. In: Saúde SdAà, editor. 9th ed. Brasília, Brasil: Ministério da Saúde; 2015. [ Links ]

2 WHO. Global status report on blood safety and availability. Geneva: World Health Organization; 2017. [ Links ]

3 Gonçalez TT, Sabino EC, Chen S, Salles NA, Chamone DA, McFarland W, et al. Knowledge, attitudes and motivations among blood donors in São Paulo, Brazil. AIDS Behav. 2008;12(4 Suppl.):S39-47. [ Links ]

4 Moreno EC, Bolina-Santos E, Mendes-Oliveira F, Miranda C, Sabino EC, Cioffi JG, et al. Blood donation in a large urban centre of southeast Brazil: a population-based study. Transfus Med. 2016;26(1):39-48. [ Links ]

5 Bednall TC, Bove LL, Cheetham A, Murray AL. A systematic review and meta-analysis of antecedents of blood donation behavior and intentions. Soc Sci Med. 2013;96(3):86-94. [ Links ]

6 Kumari S, Raina TR. Knowledge, attitude and practices (KAP) regarding voluntary non-remunerated blood donation (VNRBD) among the students of colleges of Jammu, India. Int J Community Med Public Health. 2015;2(1):45-50. [ Links ]

7 Qureshi A. Confronting the misbeliefs pertaining to blood donation and transfusion practices in India. Transfus Clin Biol. 2018;25(1):83-6. [ Links ]

8 Lownik E, Riley E, Konstenius T, Riley W, McCullough J. Knowledge, attitudes and practices surveys of blood donation in developing countries. Vox Sang. 2012;103(1):64-74. [ Links ]

9 Martinez EZ, Zucoloto ML. Development of a questionnaire to assess knowledge regarding blood donation in a Brazilian population. Rev Bras Hematol Hemoter. 2016;38(2):175-7. [ Links ]

10 Renzaho AM, Polonsky MJ. Examining demographic and socio-economic correlates of accurate knowledge about blood donation among African migrants in Australia. Transfus Med. 2012;22(5):321-31. [ Links ]

11 Paim J, Travassos C, Almeida C, Bahia L, Macinko J. The Brazilian health system: history, advances, and challenges. Lancet. 2011;377(9779):1778-97. [ Links ]

12 IBGE (Instituto Brasileiro de Geografia e Estatística). Panorama do município de Ribeirão Preto; 2017. Available from: https://cidades.ibge.gov.br/brasil/sp/ribeirao-preto/panoramaLinks ]

13 Ferreira MP, Dini NP, Ferreira SP. Espaços e dimensões da pobreza nos Municípios do Estado de São Paulo: Índice Paulista de Vulnerabilidade Social - IPVS. São Paulo Perspect. 2006;20(1):5-17. [ Links ]

14 ABEP. Critério de Classificação Econômica Brasil – 2015 Brasil; 2015. Available from: http://www.abep.org/criterio-brasilLinks ]

15 Kelley TL. The selection of upper and lower groups for the validation of test items. J Educ Psychol. 1939;30(1):17-24. [ Links ]

16 Crocker L, Algina J. Introduction to classical and modern test theory. United States: Cengage Learning; 1986. [ Links ]

17 Ebel RL. Measuring educational achievement. Prentice-Hall; 1965. [ Links ]

18 Austin PC, Escobar M, Kopec JA. The use of the Tobit model for analyzing measures of health status. Qual Life Res. 2000;9(8):901-10. [ Links ]

19 Gonçalez TT, Oliveira CD, Proietti AB, Moreno EC, Miranda C, Larsen N, et al. Motivation and social capital among prospective blood donors in three large blood centers in Brazil. Transfusion (Paris). 2012;53(6):1291-301. [ Links ]

20 Boulware LE, Ratner LE, Ness PM, Cooper LA, Campbell-Lee S, LaVeist TA, et al. The contribution of sociodemographic, medical, and attitudinal factors to blood donation among the general public. Transfusion (Paris). 2002;42(6):669-78. [ Links ]

21 Silva RM, Kupek E, Peres KG. Prevalence of blood donation and associated factors in Florianópolis, Southern Brazil: a population-based study. Cadern Saúde Públ. 2013;29(10):2008-16. [ Links ]

22 Zago A, Silveira MF, Dumith SC. Blood donation prevalence and associated factors in Pelotas, Southern Brazil. Rev Saúde Públ. 2010;44(1):112-20. [ Links ]

23 Couto MT, Pinheiro TF, Valença O, Machin R, Silva GS, Gomes R, et al. Men in primary healthcare: discussing (in) visibility based on gender perspectives. Interf Comun Saúde Educ. 2010;14(33):257-70. [ Links ]

Received: December 18, 2017; Accepted: March 21, 2018; Published: June 11, 2018

*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. E-mail address: mirianezucoloto@gmail.com (M.L. Zucoloto).

Conflicts of interest

The authors declare no conflicts of interest.

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