Is health literacy of adolescent athletes’ parents whose children belonged to sports clubs related to their children’s intention to receive medications, vaccines, supplements, and energy drinks? A cross-sectional study | BMC Public Health

Survey

A cross-sectional anonymous online questionnaire survey was conducted between March 8, 2021, and March 9, 2021. A questionnaire was distributed to males and females aged 30–59 years (approximately 198,218 people) residing in Japan who were registered with an Internet research company (Cross Marketing Co., Ltd.) and met the selection criteria (parents of elementary-school to high-school students who belonged to athletic clubs). The research firm in this study utilizes an unbiased panel of individuals representing various demographics, including age, sex, place of residence, marital status, occupation, and parental status [15]. Data from a total of 2,000 participants were collected by first-come, first-served in this study and evenly divided by sex and age. Response receipt was closed when the target number of respondents for each sex and age group was reached.

Contents of the questionnaire

The survey items included basic information regarding respondent characteristics (sex, age, educational background, marital status, and number of children), level of sports activities (no competition, municipal-level, prefectural-level, and national-level competition), engagement to sports (previously or currently), and information regarding their children (sex, age, and level of sports). Respondents were asked to report on their most competitive child if they had multiple children.

The respondents’ intentions to receive prescription drugs, over-the-counter drugs, herbal medicines, vaccines, supplements, and nutritional drinks for their children were investigated using a 4-grade scale; (1) not wanting to receive at all, (2) not wanting to receive much, (3) want to receive, and (4) actively want to receive. Items related to the health literacy of the respondents were implemented in 16 items with reference to the Japanese version of the European Health Literacy Survey Questionnaire (HLS-EU)-Q47 [16, 17]. Each item was measured in five stages: 0. do not know, (1) very difficult, (2) somewhat difficult, (3) somewhat easy, and (4) very easy. The health literacy score was calculated using the following formula after treating “0. do not know/does not apply” on a 5-point scale as a missing value. To compare our findings with those of previous studies, we calculated the health literacy score based on the following formula, resulting in a final score ranging from 0 to 50 points. Health Literacy Score Criteria were divided into four levels: “poor” (0–25), “problematic” (> 25–33), “adequate” (> 33–42), and “excellent” (> 42–50).

Further, the Cronbach’s α coefficient was calculated to be 0.947, indicating the reliability of the self-report-based survey.

Health Literacy Score = (Average– 1) x (50/3) [17].

Sample size

The G*Power software, version 3.1.9.7 (Heinrich-Heine-Universität, Düsseldorf, Germany) was utilized to determine the power of the sample size by logistic regression [18, 19]. Given the significance level set with Odds ratio = 1.3, Pr(Y = 1|X = 1) H0 = 0.2, α = 0.01, β = 0.95, R2 other X = 0 and X distribution = Normal, the required sample size should be at least 1,443 individuals.

Analysis

A t-test and one-way analysis of variance were performed to determine the relationship between the respondents’ basic information and health literacy.

The respondents’ health literacy data were not normally distributed. Therefore, in this study, we used logistic regression, which is not related to normal distribution. Binary logistic regression analysis was performed to analyze the relationship between respondents’ basic information and health literacy and their intention to receive medicines, supplements, etc. for their children, and the odds ratio (OR) was calculated. The variables of the binomial logistic regression analysis were the respondents’ and children’s basic information and health literacy scores as independent variables, and the respondents’ willingness to receive medicines, vaccines, supplements, and energy drinks for children as dependent variables. Statistical software SPSS Statistics 27 (SPSS Inc., Chicago, IL, USA) was used for the analyses. Statistical significance was set at P < 0.05.