To the best of our knowledge, the present study is the first to conduct comprehensive assessment of knowledge of risk factors and warning signs for CVDs and predictors of adequate knowledge scores among young and middle-aged adults in rural Tanzania. The study found low knowledge of risk factors and warning signs for CVDs. Despite the fact that two-thirds of the participants had heard or read about CVDs, only quarter (25.4%) had good knowledge of risk factors, 17.5% had good knowledge of warning signs and 11.7% had good knowledge of both risk factors and warning signs for CVDs. More than half (55.1%) of the participants had poor or no knowledge of risk factors and warning signs. The study has also identified individual, socio-demographic and behavioral factors as predictors of knowledge of risk factors and warning signs for CVDs.
Source of information about CVDs
In our study, at least two-thirds of the participants had heard about CVDs. The main sources of knowledge of risk factors and warning signs for CVDs were relatives/neighbors, radio, other health care providers and doctors. Internet and social media were the least mentioned sources of information in this population mainly because of the rural nature of the study setting. It is also possible that people use internet and social media for other things rather than search for health information. We also observed sex differences in the sources of information with radio being the main source of information among men while relatives/neighbors were the main source among women. Other studies have also reported radio [22–24], relatives/neighbors [13, 36, 37] and health care providers [35, 40, 41] as sources of information for CVDs. Our findings have indicated underutilization of health care providers for provision of CVD-related health education. Deliberate efforts must be made to effectively use radio and health care providers as channels for delivery of health education programs to increase population knowledge of risk factors and warning signs in rural settings of Tanzania. A study in Kuwait demonstrated that higher knowledge of smoking, obesity, unhealthy diet and physical inactivity were attributable to their high mass media campaign .
Knowledge of risk factors for CVDs
In our study, we found low level of knowledge of risk factors for CVDs among study participants with only quarter (25.4%) had good knowledge. Knowledge was much poor when we used open-ended questions as more than half of the participants (52.4%) could not mention even a single CVD risk factor. However, knowledge of risk factors improved when closed-ended questions were used and the proportion of participants who could not identify even a single CVD risk factor dropped to 6.9%. This improved knowledge with use of closed-ended questions may be due to most participants remembering risk factors when listed or guessed correct responses. More than half (51.4%) of the participants identified five or more risk factors. Similar to our findings, other community based studies have also reported low level of knowledge of risk factors for CVDs in the general population [13–15, 37]. On the contrary, high knowledge has been reported among studies that focused on special populations like health care providers [41, 42], secondary school teachers  and among staff of tertiary institution , meaning that education level has implication on health-related knowledge. Most participants in our study cited stress, obesity, cholesterol and physical inactivity as risk factors for CVDs. The proportion of participants who identified stress as a risk factor is comparable to that reported in a study conducted among Nigerian army force , but is much higher compare to other community based studies [14, 37, 44].
With exception of physical inactivity which was pointed out by nearly two thirds of the participants, smoking and alcohol were identified by only quarter of the participants as important risk factors for CVDs. A meta-analysis of 14 studies has shown smoking to be associated with up to 60% increased risk of stroke , and the risk was much higher for current smokers compared to ex-smokers. The literature also indicates a 30% increased risk for stroke among individual with second hand smoke exposure compared to those with no exposure at all . Although the reported prevalence of current smoker in our study was low (5.9%), the national prevalence has previously been reported as 14.1% . Thus, primary prevention interventions should target to increase population knowledge of smoking and other modifiable behavioral risk factors like alcohol and unhealthy diet.
Knowledge of warning signs for CVD event
Only 17.5% of the participants had good knowledge of warning signs while more than half (55.2%) were not able to mention even a single warning sign for CVD event. Participants’ knowledge of warning signs was lower than knowledge for risk factors. Poor knowledge of warning signs for CVD event found in this study is similar to what has previously been reported in East Africa. A study in Uganda found that 57% of the participants did not know stroke warning signs or symptoms , whereas a study in Kenya found poor knowledge of warning signs for coronary heart disease among people living with HIV .
Shortness of breath was the most commonly identified warning sign for CVD event in our study. Less than half (44.1%) of participants identified chest pain as a warning sign for CVD event. These findings contrast results of the study that reported chest pain as the most commonly identified symptom . Individuals with good knowledge of warning signs for CVD event are more likely to seek medical treatment early and consequently have better disease outcomes . Additionally, people with good knowledge of both risk factors and warning signs tend to perceive themselves to be at higher risk for the disease and are more likely to adopt healthier lifestyle behaviors . Thus, improving population knowledge of risk factors and warning signs for CVDs are likely to help adoption of healthier lifestyles for primary prevention, improve early medical care seeking behavior and consequently better prognosis among Tanzanians.
Factors associated with CVD knowledge
We found socio-demographic and economic characteristics to be associated with knowledge of risk factors and warning signs for CVDs. Knowledge of both risk factors and warning signs was higher among men compared to women. Our findings of higher CVD knowledge among men differs from other studies which reported higher CVD knowledge among females [40, 51]. Nonetheless, several other studies have reported insignificant gender differences in CVD knowledge [15, 52–54]. Higher CVD knowledge in women has been attributed to less working time among women which gives them more leisure time to watch and listen to mass media such as radio, television and newspaper . However, this is more likely to be case in urban than rural areas. In our study, which is rural, men seemed to be listening, watching and reading from mass media. This is clearly reflected by the reported source of information about CVDs where men reported to have heard about CVD from radio, television and newspapers which may explain their higher CVD knowledge.
The current study showed that participants aged 45–54 years were more knowledgeable about risk factors and warning signs compared to other age groups. These findings are suggestive that middle aged adults are more likely to seek health-related information than young individuals. Influence of age on CVD knowledge has also been reported by other studies conducted in SSA [37, 43, 55]. As expected, participants with higher education level and with formal employment were more knowledgeable about risk factors and warning signs compared to their counterparts. Other studies have also reported a positive association between higher education level with good CVD knowledge [12, 40, 53, 55, 56]. Educated individuals have higher capabilities to comprehend information including health messages delivered through various mass media channels.
Studies have reported geographical differences in CVD knowledge with those in urban settings having better knowledge compared to their counterparts in rural settings [16, 55]. Despite the fact that both Kilombero and Ulanga are rural districts, residents of Ulanga district had significantly higher knowledge about risk factors and warning signs than their counterparts from Kilombero district. Although this study did not assess ownership of community health fund (CHF) cards to draw its association with CVD knowledge, higher coverage of CHF overcomes the financial barrier to accessing health care services and consequently increase their likelihood of getting health-related messages and increase knowledge. Nonetheless, differences in CVD knowledge between the two rural districts warranties further exploration.