Introduction
Cardiovascular diseases, are the main cause of death worldwide, thus being a problem of interest in public health, in developed as well as in developing countries. In Colombia these diseases are the main cause of death, both in men and in women older than 45 years 1.
These diseases have been associated with the presence of various risk factors such as sedentarism, obesity, tobacco use, alcoholism, unhealthy diet, which usually appear early in childhood due to the technological advances in transportation, communications and entertainment and leisure, promoting an increase in hypokinetic activities 2.
The decrease of the time spent in physical activity and the increase of sedentary activities like watching TV, playing video games and using internet are evident 3,4; these do not only produce problems related to health, it also, considered from the perspective of education, connected with physical inactivity, affects motor abilities and qualities 5.
According to the report of the Pan American Health Organization -PAHO- and the World Health Organization -WHO-, 15.2 % of alcohol users and 6.8 of tobacco users are young people. In this regard, it has been established that men start smoking at the age of 17.3 years and women at the age of 18.2 years.
As to arterial hypertension, prevalence in the population older than 15 years of age is 12.6 %, equally, it is estimated that 7 % of population older than 30 years suffer from non-insulin dependent diabetes mellitus, and of these, between 30 % and 40 % are not aware they are sick 6.
Scientific evidence suggests that CD have their origins in early ages of life and that the risk of suffering from them is determined by the synergic effect, resulting from the exposure to different cardiovascular risk factors over time. For this reason, the appearance of CD in adults is connected to unhealthy habits acquired already in childhood 2. Literature shows that previous history of practicing exercise is an important factor of initiating and/or maintaining physical and sport activity. Added to this, it has been observed how the level of physical activity in individuals at early ages is reflected in their motor processes in adult ages 4,7-12.
In response to this situation, the present study was carried out with the aim of establishing which factors are associated with cardiovascular risk in the students of a high-school educational institution in the city of Cali, Colombia.
Materials and Methods
his is a descriptive, transversal and analytical epidemiological study. The established population were students aged between 15 and 19 years of age. The sample development was determined by a multistage process: in the first stage the sample size was calculated by means of Epidat software version 4.2, considering the proportion of the practice of physical activity, reported by Morales and Flórez, a confidence level of 95 %, an error rate of 5 %, and a design effect of 1, thus establishing a sample size of 227 students 13. Then, the sample was stratified by school year, according to the number of students suggested in the stratification previously conducted.
Selection criteria were: students enrolled in the educational institution where the sample was selected; age between 15 and 19 years; and, finally, acceptance and signature of the informed consents and approvals. As to the exclusion criteria, following were selected: students who present cognitive disorders; students with metabolic disorders, pregnant students, and students with cardiopulmonary diseases.
An informed consent for adults stating the objectives, purposes and information regarding the instruments of information gathering was made available for participants. Additionally, for minors an informed approval with which their parents or guardians endorse their participation in the study was also given.
The assessed variables were considered according to the reviewed background information. The studied socio-demographic variables were age, gender, schooling level, level of physical activity (IPAC questionnaire), as well as alcohol and tobacco use. The anthropometric variables measured in the study were weight, valued by means of a TANITA scale; waistline measured with the help of a SECA 214 portable height measuring rod; and the waist circumference assessed with a flexible tape measure. In order to measure cardiovascular risk, waist and hip circumferences were assessed obtaining, through the division of both values, the results of low, high or very high risk according to the parameters established by the WHO 14.
Finally, a univariate descriptive analysis was conducted, thus determining the frequency and proportion of the qualitative variables, as well as the measures of central tendency and dispersion for the quantitative variables. The bivariate analysis was developed based on the associations found between the study variables and the cardiovascular risk thus determining the statistical significance of these associations on the basis of non-parametrical statistical tests (chi-square); besides identifying the intensity of the associations through Odds Ratio (OR).
Results
According to the data described, a male predominance of 70.2 % was found; the school grade with the highest number of students was the tenth grade with 54.4 % (n=124), as to tobacco and alcohol there is a predominance of non-use with 96.5 % (n=154) and 67.5 %, respectively (table 1).
Frequency | % | 95 % ci | |
---|---|---|---|
Gender | |||
Female | 67 | 29.4 | [23.75 - 35.55] |
Male | 160 | 70.2 | [64.24 - 76.11] |
Schooling Level | |||
Eighth Grade | 8 | 3.5 | [1.1 - 5.89] |
Ninth Grade | 64 | 28.1 | [22.24 - 33.9] |
Tenth Grade | 124 | 54.4 | [47.92 - 60.85] |
Eleventh Grade | 31 | 13.6 | [9.14 - 18.65] |
Tobacco Use | |||
Yes | 7 | 3.1 | [0.8 - 5.3] |
No | 220 | 96.5 | [94.1 - 98.88] |
Alcohol Use | |||
Yes | 73 | 32 | [25.96 - 38.07] |
No | 154 | 67.5 | [61.47 - 73.62] |
95 % ic: 95 % Confidence Index
Regarding the anthropometric measures (table 2), findings show for the variable body mass index a higher frequency of normal weight, with 62.2 % (n=142); for waist circumference a normal frequency, with 90.7 % (n=206); a low cardiovascular risk, with 96 % (218), was found; and the level of physical activity shows a high level, with 51.5 % (n=117).
Frequency | % | 95 % ci | |
---|---|---|---|
BMI | |||
Low Weight Low Weight 25 11 [6.94 - 15.09] | 25 | 11 | [6.94 - 15.09] |
Normal Weight | 142 | 62.6 | [56.26 - 68.85] |
Overweight | 42 | 18.5 | [13.45 - 23.55] |
Obesity | 18 | 7.9 | [4.4 - 11.44] |
Waist Circumference | |||
Normal | 206 | 90.7 | [86.98 - 94.54] |
High Risk High Risk | 15 | 6.6 | [3.37 - 9.83] |
Very High Risk | 6 | 2.6 | [0.55 - 4.73] |
Cardiovascular Risk | |||
Low | 218 | 96 | [93.5 - 98.57] |
High | 9 | 4 | [1.42 - 6.5] |
Level of Physical Activity | |||
Low | 55 | 24.2 | [18.6 - 29.8] |
Moderate | 55 | 24.2 | [18.66 - 29.8] |
High | 117 | 51,.5 | [45.04 - 58.04] |
BMI: Body Mass Index. 95 % ci: 95 % Confidence Index.
Table 3 shows that the mean age for females reached 16.22, and for males 15.98 years old. Regarding the variables weight and height, a higher mean was established in males, with 65.97 kilograms and 1.7 meters, respectively; it applies equally to the waist circumference with a mean of 76.56 centimeters. However, the variable BMI, in females showed a higher mean with 23.4 Kg/cm2.
BMI: Body Mass Index. 95 % ci: 95 % Confidence Index. sd: Standard Deviation. Max: Maximum. Min: Minimum
Table 4 shows the statistical association between the use of alcohol and cardiovascular risk, OR indicates that the possibility students using alcohol have of suffering from a cardiovascular disease is 1.062 times higher compared to those not using alcohol drinks. Similarly, a statistical association is established between BMI and cardiovascular risk, proving that students with a high BMI are 1.062 more likely to contract a cardiovascular disease.
Significance level: p<0.05. bmi: Body Mass Index. X2: Chi-square. or: Odds Ratio. ci: Confidence Intervals
The ROC represents graphically the relation between sensitivity and the specificity inverse, in this regard and once the variables that influence cardiovascular risk in students were determined, a ROC curve analysis was conducted in order to establish the probability of cardiovascular risk in this population, thus finding that the area beneath the curve reaches 0.816, that is to say, a student who has the habit of using alcohol and whose BMI indicates overweight or obesity has a probability of 81 % of having cardiovascular risk.
Discussion
This research has as objective to determine the factors related to cardiovascular risk in school students of an educational institution in Cali, Colombia, with a sample of 227 students, where males (70.2 °%, n=160) predominated over females (29.4 °%, n=67), thus differing from the study of Ferreira et al. in 2013 that showed a higher frequency in females (57 °%) in contrast to males (43 °%) 15.
Predominance of the negative answer related to tobacco use (96.5 °%, n=220) stands out, staying in line with the 2016 study of Cúneo et al., in which "non-use" was found in 80 °% of the interviewees 16.
For its part, the 2009 study of Sáez and Bernui established that 46 °% of the evaluated population present a high prevalence of being passive smokers who reported being exposed to tobacco smoke at home and/or in other places, a fact that increases in 25 °% the risk of cardiorespiratory diseases 17,18.
Alcohol use showed a low prevalence (32 °%, n=73), a fact that does not correspond to López et al., who identified an alcohol use of 88 °% of students, since their motivations are consistent with a behavior of imitation and are encouraged by their friends 19. According to Jackson et al., alcohol use grows during teenage and youth, a condition that raises in the surroundings of educational institutions, and decreases as the young adult reaches the age of thirty years 20,21.
Regarding the BMI, a higher prevalence of normal weight (62.6 °%, n=142) was found, similar to what González et al. have established, where the prevalence of normal weight was 61.6 °% 22. These findings could be a consequence of a low sedentary behavior, due to the socioeconomic and cultural characteristics of the students attending this particular school.
In this respect, a positive ratio between BMI and waist circumference is evidenced, suggesting that the presence of obesity is due to a greater subcutaneous fat accumulation or, in some cases, visceral fat; for this reason, this ratio is a predictor of cardiovascular risk 23-25.
A normal condition of weight prevails in the study, taking into account that this variable reflects a behavior of a high level of physical activity (51.5 °%, n=117). Such behavior allows maintaining a balance between energy intake and energy expenditure, making possible that the interviewees maintain a normal abdominal girth (90.7 °%, n=206), allowing, in turn, a low cardiovascular risk (96 °%, n=218).
The obtained results concerning overweight (18.5 °%, n=42) and obesity (7.9 °%, n=18) are supported by Lavielle et al. who found 7.6 °% overweight and 20.1 °% obesity, as well as Ferrer et al. who found an overweight prevalence of 13.8 °% and an obesity prevalence of 6.8 °% 26,27.
Though these data show a low prevalence, there is evidence of the presence of a condition that can raise over time considering the current professional development that increases duties leading individuals to hypokinetic working conditions.
The level of physical activity of our study is derived from the answers to the IPAQ questionnaire in which interviewees report frequent participation in sport activities. They also report that for their daily activities they move between their homes and the educational institution walking, cycling or using skateboards or skates. These results are similar to what Yang et al. have established, with a prevalence of 71.5 °% of high or vigorous physical activity, with study participants practicing physical exercise for at least 60 minutes daily 28. However, Lavielle et al. identified a prevalence of low physical activity of 66.3 °% 26.
Based on the background knowledge, promoting physical activity responds to having the support of places that provide the motivation of practicing even physical exercise like parks and facilities that stimulate this practice; and the lack of these locative characteristics conduct to other type of activities that, according to sociocultural conditions, result in violence, forcing the neighborhood to opt for practicing sedentary activities 22,26. The study of Torres et al. reported a high level of physical activity of 79 °% in individuals living in rural areas, where people are characteristically involved in farming activities, among others, besides traveling long distances between their homes and the educational institutions 29.
A statistical association between alcohol use and cardiovascular risk (p=0.035) is evident, a finding that corresponds to Telumbre and Sánchez who reported that alcohol use affects brain functions, as well as the functions of the organs and body systems, a fact that in turn is associated with incidence of health problems such as cardiovascular, endocrine and metabolic diseases, among others, a behavior to which attention must be paid specially in young people 30. They also report that 72.1 °% of adolescents have used alcohol once in their lives, and, according to the results of the implemented Alcohol Use Disorders Identification Test, AUDIT, it was evidenced that 24.8 °% of the interviewees presented a detrimental alcohol use, and 38 °% presented a harmful alcohol use 26.
O'Keefe et al. affirm that the effects of alcohol in health depend on the consumed amount and on the consume patterns 31. On the other hand, excessive alcohol intake increases the risk of motor vehicle accidents, strokes, cardiomyopathies, severe myocardium infarct, suicide, fetal alcoholism syndrome, among others 24,32,33.
BMI has been accepted to be the main indicator of overweight and obesity. A statistically significant relation between BMI and cardiovascular risk p=0.005 was identified, corresponding to the study of Alvarez et al., who established a significance level between a BMI alteration and the cardiovascular risk factors, with a prevalence of overweight (31 °%) and obesity (10.9 °%), indicating that both variables presented in an adolescent population turn into predisposing factors for the appearance of cardiovascular diseases 34. Moreover, Lima et al. identified a strong association between overweight and quality of life (p=0.01), thus proving that BMI alterations in terms of excess fat become a determining factor of poor quality of life perceived by adolescents 35.
Monitoring and controlling different cardiovascular risk factors provide the best prevention strategy aiming at reducing the incidence of cardiovascular pathologies in the future, particularly when these are identified at an early age; here is where the educational institutions can develop education and control programs on these variables, thus promoting alternatives that help reducing habits that contribute to the appearance of such factors. In this sense, all health professionals play a very relevant role since they contribute with different promotion and risk factor prevention strategies that, together with interdisciplinary work, could strengthen the various interventions for their identification and/or control.
Therefore, it is necessary and urgent to provide more opportunities of physical activity for adolescents; the practice of physical activity needs also to be highly valued, thus raising awareness among the families, the teachers and all social agents on the fact that promoting physical exercise and sports, especially non-competitive sports, is the best way to shape a healthier future for the younger.
This needs to be further improved by generating new processes and educational strategies, besides frequently monitoring the behavior of physical activity of school students of the city, thus stimulating the formulation of government policies for the allocation of resources aiming at promoting healthy habits.
In this sense, and with the help of these findings, institutions can create control programs together with health professionals who contribute with the inclusion of the health sector and effective investment strategies