Accurate assessment of HBP knowledge is an important first step to identify individuals in need of HBP education, since knowledge is often a prerequisite for a patient to perform appropriate HBP self-care as shown in previous research.5
HBP knowledge may be particularly critical in the management of HBP among non-English speaking immigrants such as KAs who often have very limited resources in health information.17
Based on the descriptive statistics (), KAs were generally knowledgeable about etiology and common risk factors (e.g., drinking, obesity, lack of exercise, salt) of HBP and correctly identified “high” versus “good” BP values. On the contrary, a significant proportion of KAs answered incorrectly items about HBP symptoms and diagnosis, HBP medications, harmful effects of HBP over time, and the relationship between BP and cold weather. KAs' lower knowledge about these items, particularly HBP medications is of concern in view of their high prevalence of uncontrolled HBP and less access to medications.12,14
These results suggest and support continuing need for educational interventions to address their insufficient knowledge in key areas of HBP management.
The reliability and validity of the HKT were supported in the combined sample of KA patients with adequate differentiation between those with and without HBP control. Item-total correlations for the 21 items on the HKT were all within the acceptable range of 0.1527
for the total sample with internal consistency coefficient of 0.70, meeting the minimum acceptable level of reliability. The result may have to do with the item heterogeneity in that the HKT addresses knowledge of different HBP risk factors (e.g., obesity, diet, drinking) or various symptoms and consequences of HBP. Nevertheless, the HKT yielded a reliability estimate that should allow researchers to use it with some confidence. Indeed, the usefulness of the HKT as an outcome measure has been reported in a separate study with significant changes in HKT scores at 3 months follow-up (p=0.000) after an educational intervention for KAs.16
IRT findings offer insights on the overall and specific performance of the HKT items. In general, the information curves for the HKT items revealed that the 21 items performed in a similar pattern as a cluster at the lower end of the HBP knowledge trait. Location parameters (b) of the 21 items were between 0 and -3. The results suggest that the HKT is best at quantifying differences among respondents who are less knowledgeable about HBP, particularly within 3 standard deviations below the group mean. All the items on the HKT were found to be at least moderately discriminating with the discriminating (a) parameters ranging from 0.62 to 1.38, though several items were particularly good at distinguishing between respondents at different levels of HBP knowledge. Taken together, the current set of items on the HKT will perform best among quantifying differences amongst individuals with lower HBP knowledge and hence, can be useful for identifying individuals who are in need of further education about HBP.
While this study offers great opportunities to measure HBP knowledge among recent KA immigrants in the Baltimore-Washington metropolitan area, an understudied and vulnerable population, there are a number of limitations to consider. The two samples included in the analysis were participants in educational intervention trials for HBP control. People who volunteered to be in those trials were likely to be more interested in their health and HBP management than those who did not. Therefore, the level of HBP knowledge reported in this study might have been an overestimate of the HBP knowledge in the larger KA population, limiting the generalizability of the findings. Additionally, the HKT was administered in the two behavioral intervention trials along with a number of other study questionnaires. Therefore, participant fatigue might have been introduced, influencing participant performance on the measure.
In conclusion, while there is no standard to measure the level of HBP knowledge required for adequate management of HBP, we developed the HKT, a measure that was modified from the National Heart Blood and Lung Institute hypertension knowledge questionnaire19
as well as a literature review and community input, to assess patients' general knowledge of HBP. The reliability and validity of the HKT was supported in this sample of KAs. The HKT was also sensitive in detecting differences among those with and without adequate HBP control. Furthermore, given that there are 21 items written at the 4th
grade level, the HKT can be easily self-administered, and may be particularly helpful in identifying patients with low HBP knowledge. With continued validation, clinicians can use the knowledge gaps demonstrated on the HKT to provide the basis for additional hypertensive management education for KAs with HBP. Future research is warranted to evaluate the HKT in other ethnic samples of hypertensive patient populations.