Acceptance of illness mediate the effects of health literacy on self-management behaviour

Abstract

Background

Self-management is crucial for blood pressure control and subsequent disease prevention. Health literacy and acceptance of illness may contribute to self-management behaviour; in addition, acceptance of illness may mediate the effects of health literacy on self-management behaviour among patients with hypertension.

Objective

The aims of the research were to examine whether health literacy and acceptance of illness were associated with both pharmacological and non-pharmacological management behaviour and examine the possible mediating effects of the acceptance of illness in patients with hypertension.

Methods

Hierarchical regression analysis was conducted to analyse the relationships between health literacy, acceptance of illness, pharmacological and non-pharmacological management behaviours. Mediation effects were examined by the PROCESS macro.

Results

This was a cross-sectional study. A total of 478 hypertensive patients completed measures of health literacy, acceptance of illness, self-management, social support, depression, physical function and demographic and clinical characteristics. Functional, communicative, critical health literacy and acceptance of illness showed positive associations to pharmacological and non-pharmacological management behaviour. Acceptance of illness mediated the relationships between three types of health literacy, pharmacological and non-pharmacological management but the effects size and pathway differed. In detail, functional health literacy influenced pharmacological and non-pharmacological management behaviour mainly by indirect effects mediated by the acceptance of illness, but communicative and critical health literacy influenced pharmacological and non-pharmacological management behaviour mainly by direct effects.

Conclusions

Acceptance of illness mediated the relationships between three types of health literacy and self-management. Health literacy and acceptance of illness should be addressed when taking measures to improve patients’ self-management behaviour.

Introduction

Hypertension is a major cause of cardiovascular diseases.¹ It affects over 1.2 billion people around the world and has become a worldwide health priority.² It was estimated that there were approximately 292 million patients with hypertension in China during 2013–2014. However, only 26.4% of patients with hypertension were well treated and 9.7% showed well-controlled blood pressure, foreshadowing a substantial unnecessary disease burden.¹

Self-management includes the activities in which individuals engage to promote wellbeing with support from family, communities and care providers.³ It encompasses both pharmacological and non-pharmacological management behaviour such as adherence to taking medicines, blood pressure monitoring, follow-up consults, healthy diet and exercise, non-smoking and abstaining from alcohol.⁴ The 2017 scientific statement of the American Heart Association highlighted the significance of self-management on building healthier lives and achieving optimal treatment outcomes.⁵

Health literacy is believed to be a basic criteria for patients to perform self-management and it is defined as ‘the personal traits and social resources needed for individuals to access, understand, appraise and use information and services to make decisions about health’.⁶ However, previous studies on the associations between health literacy and self-management behaviour have yielded conflicting results. Some research has demonstrated that higher health literacy directly facilitates patients to perform better self-management behaviour,⁷ whereas others failed to confirm any such direct associations.⁸

The inconsistent results might be attributed to several reasons. At the early stage, the definition of health literacy just highlighted peoples’ basic reading and writing skills. Later, with much more in-depth and comprehensive understanding, Nutbeam⁹ pointed out that health literacy was a capacity more than basic reading and writing, and he further generalised it into three different types: functional, communicative and critical health literacy. Functional health literacy refers to basic reading and writing skills. Communicative literacy refers to advanced skills that patients need to extract information and derive meaning from communication, and critical literacy refers to more advanced skills for patients to criticise, analyse and reflect on information and use this information to control life events and situations. However, some research mainly focused on the relationships between self-management behaviour and functional health literacy.^10,11 In addition, little research examined the effects of health literacy on self-management by considering the indirect effects through potential mediators, especially in the context of patients with hypertension. These limitations might hinder the process to uncover the mechanism explaining the relationships between health literacy and self-management and restrict the efficiency of existing interventions to improve patients’ self-management behaviour.

As a core component of the process of disease adaptation and health behaviour decision-making,¹² the acceptance of illness has been thought of as a predictor of both self-management and health literacy. Acceptance of illness is described as ‘approval of the fact of being ill, recognition of the need to adapt to the illness condition, perception of coping with aversive consequences’.¹³ It is demonstrated that low level acceptance of illness could decrease patients’ adherence to both pharmacological and non-pharmacological therapy.^14,15 In addition, acceptance of illness was strongly correlated to patients’ educational status,¹⁶ which was highly paralleled to health literacy among patients with chronic diseases.

The capability, opportunity, motivation and behaviour model (COM-B model) is one of the most popular framework to understand behaviour,¹⁷ and it would provide theoretical guidelines to clarify the relationships among health literacy, acceptance of illness and self-management behaviour in this research. Based on the COM-B model, capability, opportunity as well as motivation interact to generate behaviour, and motivation acts as the keystone to link basic capability and concerned behaviour. Therefore, capability was described as the individual’s psychological and physical capacity to engage in the activity concerned. Motivation referred to all psychological processes that energise and direct behaviour (such as emotional responding). In previous research, health literacy was theoretically believed to be the basic capability of patients to perform self-management behaviour, and acceptance of illness was regarded as an important emotional responce to the occurrence of illness. Thus we hypothesised that the acceptance of illness (motivation) might mediate the effects of health literacy (capability) on self-management (behaviour). Of note, self-management is a complex behaviour which could be influenced by several factors.³ Recent research¹⁸ has suggested that physical function is integral to successful self-management, because nearly all self-management behaviour relies on patients’ basic physical function. While psychological distress, especially depressed mood, showed negative effects on self-management behaviour.³ Social support could facilitate patients to perform self-management behaviour by providing both subjective and objective support.³ Given their significant effects on self-management, besides patients’ general characteristics, we also included these factors as potential covariates in the research.

The specific aims of this research were to: (a) detect the effects of different types of health literacy to pharmacological and non-pharmacological management behaviour after controlling other potential covariates; (b) examine the mediating effects of the acceptance of illness on the relationships between health literacy, pharmacological and non-pharmacological management behaviour after controlling other potential covariates.

Methods

Sample and procedure

This was a cross-sectional study conducted at hypertension outpatient departments of three tertiary hospitals in Tianjin, China, from June to October 2018. The sample size estimated was 171 based on a moderate ƒ2 effect size of 0.15, α of 0.05 and power of 0.90. A total of 478 patients with hypertension was recruited. These patients were referred by their general practitioners from community clinics. Each recruited patient received verbal information about the study and signed an informed consent form at first. Then a face-to-face interview was performed by two researchers with postgraduate degrees to collect information. After the interview, every participant would get a small gift as a reward.

Patients were eligible if they met the following criteria: (a) had a documented diagnosis of hypertension for at least 3 months; (b) were prescribed one or more antihypertensive drugs; (c) were over18 years of age; and (d) were able to understand and write Chinese. The exclusion criteria were: patients with (a) active and severe infection, such as tuberculosis; (b) dementia or mental diseases; or (c) inherent or non-disease-induced physical disability. The study was approved by the research ethics committees of Tianjin Medical University. The ethics number is TMUHMEC2017009. Quality control was assured by technician recertification, procedural checklists and data review.

Measurements of main variables

Health literacy

The functional communicative and critical health literacy scale (FCCHL) was used to assess health literacy capability. It includes 12 items distributed into three dimensionalities: functional, communicative and critical health literacy. Each item is rated from 1 to 4 (‘never’ to ‘often’), with a higher score reflecting abundant health literacy capability. The Chinese version of FCCHL is confirmed to be reliable and valid with a Cronbach’s α of 0.891.¹⁹ In the present research the Cronbach’s α was 0.814.

Acceptance of illness

The acceptance of illness scale (AIS) was used to measure patients’ acceptance of illness. The AIS is an 8-item scale, and each item is rated on a Likert 5-point response, from 1 (‘strongly agree’) to 5 (‘strongly disagree’). The overall score, between 8 and 40 points, provides the degree of adaptation to a disease; the higher the score, the greater the acceptance of a given condition. The Chinese version of AIS is confirmed to be reliable and valid.²⁰ In the present research the Cronbach’s α was 0.762.

Self-management behaviour

The Chinese version of the 21-item self-management behaviour scale was adopted to evaluate participants’ self-management behaviour. All items are distributed into two subscales: pharmacological management (adherence to pharmacy, blood pressure monitoring) and non-pharmacological management behaviour (lifestyle changing behaviour, including a healthy diet, exercise and avoiding risk factors). Each item is rated on a 5-point Likert response (1=never, 5=always). A higher score is associated with patients’ higher capability to perform self-management. Cronbach’s α of the scale is 0.854, which shows high reliability.²¹ In the present research the Cronbach’s α was 0.833.

Measurement of other variables

The following variables were included in the analyses as covariates: patients’ basic demographic and clinical information, physical function, depression status and social support.

Demographic and clinical information

Demographic and clinical information were obtained from medical records and patient interview, which included gender, age, education level, employment status, payment of medical expenses, monthly income, disease duration, comorbidity status, body mass index and family history of cardiovascular diseases. Monthly income was categorised into two classes, less than 2000 and 2000 or greater renminbi (RMB) according to the consumption expenditure and income per capita announced by the Tianjin Bureau of Statistics.

Physical function

The Duke activity status index (DASI) was used to measure patients’ physical function. DASI is a 12-item scale. Each item has two response options (‘yes’ or ‘no’), and total scores range from 0 to 58.2, with higher scores indicating better physical function. The Chinese version of DASI is confirmed to be reliable and valid with a Cronbach’s α of 0.704.²² In the present research the Cronbach’s α was 0.743.

Depression status

The self-rating depression scale (SDS) was adopted to measure patients’ depression status. SDS is a widely used scale with 20 items. Each item is rated from 1 to 4. The total score ranges from 1 to 80, wherein a higher score reflects more severe depression status. The Chinese version of SDS is confirmed to be reliable and valid.²³ In the present research the Cronbach’s α was 0.762.

Social support

The Chinese version of the social support scale (SSS) was adopted to assess the social support of patients with hypertension. The scale includes 10 items and measures three types of social support, subjective support, objective support and availability. Each item is rated on a 5-point Likert response, with a higher score reflecting abundant social support. The Chinese version of SSS is confirmed to be reliable and valid.²⁴ In the present research the Cronbach’s α was 0.824.

Statistical analysis

Data management and analysis was performed using SPSS 20.0 software. Continuous variables with normal distribution were expressed as mean ± standard deviation (x ± s), non-normal distribution variables were presented as median (interquartile range) and categorical variables were presented as number and percentage. The independent t test and one-way analysis of variance (with the Bonferroni post hoc test) were performed to examine the difference in pharmacological and non-pharmacological management behaviour by sample characteristics. Pearson r coefficients were calculated to detect the correlations among physical function, depression status, social support, acceptance of illness, health literacy and self-management behaviour.

Then hierarchical regression analysis was conducted to examine the relationships among three different types of health literacy, acceptance of illness and pharmacological and non-pharmacological management behaviour. Covariates (i.e. marital status, education level, monthly income, payment of medical expenses and comorbidity status) were entered into model 1; covariates, three different types of health literacy were entered into model 2; and covariates, three different types of health literacy and acceptance of illness were entered into model 3. The statistical significance level was set at 0.05 with a two-tailed test.

In this research, hypothesised mediation effects were performed by the PROCESS macro of SPSS with a 95% bias-corrected bootstrap confidence interval using 5000 bootstrap samples. Three types of health literacy (functional, communicative, critical health literacy) were set as independent variables in three separate analyses, acceptance of illness as mediator, pharmacological management behaviour as outcome variable and other variables as covariates (i.e. marital status, education level, monthly income, payment of medical expenses and comorbidity status). The same method was used to assess the mediation effects of acceptance of illness between the relationships of three types of health literacy and non-pharmacological management behaviour. If the confidence interval includes zero, this means that there is no significant mediation (indirect) effect at the 5% level of significance.

Results

Sample characteristics

A total of 478 participants was recruited into the research; the sociodemographic and clinical information are presented in Table 1. A large proportion of participants (58.2%) were women. Over half (51.9%) of participants earned more than 2000 RMB per month. More than one third of patients (39.1%) had a comorbidity, such as diabetes, coronary heart disease, gastric ulcer, etc.

Correlations of pharmacological and non-pharmacological self-management behaviour and other variables

Comparisons of pharmacological and non-pharmacological management behaviour by the sample characteristics are presented in Table 1. The results indicated that both patients’ pharmacological and non-pharmacological management behaviour was influenced by marital status, income, education level, comorbidity status and medical insurance. As presented in Table 2, all variables except depression status were significantly correlated to both pharmacological and non-pharmacological management behaviour.

Results of multicollinearity diagnostics

The tolerance was well above 0.5, and the variance inflation factor was well below 2, suggesting that multicollinearity among variables did not exist in the analysis.

Hierarchical analysis of pharmacological management behaviour

As presented in Table 3, in model 1, social support, education level (senior high school or higher), marital status (married) were positively associated with pharmacological management behaviour. In model 2, education level (senior high school or higher), marital status (married), functional, communicative and critical health literacy were positively related to pharmacological management behaviour. Among all variables, communicative health literacy showed the strongest correlation to pharmacological self-management behaviour, followed by critical health literacy. In model 3, education level (senior high school or higher), marital status (married), functional, communicative and critical health literacy and acceptance of illness were positively associated with pharmacological management behaviour, and acceptance of illness showed the strongest correlation to pharmacological management behaviour.

Hierarchical analysis of non-pharmacological management behaviour

As presented in Table 3, in model 1, social support, education level (senior high school or higher), marital status (married), depression status were positively associated with non-pharmacological management behaviour, while family history of cardiovascular diseases (yes) was negatively associated with non-pharmacological management behaviour. In model 2, education level (senior high school or higher), marital status (married), depression status, functional, communicative and critical health literacy were positively related to non-pharmacological management behaviour. Among all variables, critical health literacy showed the strongest correlation to non-pharmacological self-management behaviour, followed by communicative health literacy. In model 3, education level (senior high school or higher), marital status (married), depression status, communicative, critical health literacy and acceptance of illness were positively associated with non-pharmacological management behaviour, and acceptance of illness showed the strongest correlation to non-pharmacological management behaviour.

Mediation effects of acceptance of illness on the relationships between health literacy and pharmacological management behaviour

The estimated regression coefficients for three separate simple mediation analyses of acceptance of illness on the relationships between health literacy and pharmacological management are presented in Table 4. As the results showed, acceptance of illness was proved to be a significant mediator linking three types of health literacy and pharmacological management behaviour. Functional health literacy influenced pharmacological management behaviour mainly by an indirect effect with the ratio of the indirect to the direct effect of 120.12%. Communicative health literacy influenced pharmacological management mainly by a direct effect with the ratio of the indirect to the direct effect of 39.17%, and critical health literacy influenced pharmacological management mainly by a direct effect with the ratio of the indirect to the direct effect of 12.17%.

Mediation effects of acceptance of illness on the relationships between health literacy and non-pharmacological management behaviour

The estimated regression coefficients for three separate simple mediation analyses of acceptance of illness on the relationships between health literacy and non-pharmacological management behaviour are presented in Table 4. As the results showed, acceptance of illness was proved to be a significant mediator linking functional, communicative health literacy and non-pharmacological management. Functional health literacy influenced non-pharmacological management behaviour by complete indirect effects mediated by the acceptance of illness with indirect effects of 0.6376. While communicative health literacy influenced non-pharmacological management behaviour mainly by direct effects with the ratio of the indirect to the direct effects of 38.10%, critical health literacy influenced non-pharmacological management mainly by direct effects with the ratio of the indirect to the direct effects of 8.91%.

Discussion

This research provides new evidence regarding the importance of health literacy and its relationship to self-management behaviour. We found that functional, communicative and critical health literacy were all significant predictors of different aspects of self-management behaviour. These findings were similar to those of previous research. Both Heijmans et al.²⁵ and Inoue et al.²⁶ demonstrated the significant correlations between functional, communicative, critical health literacy and self-management behaviour. However, in the research of van der Heide et al.²⁷ critical health literacy was not correlated to patients’ perceived ability to perform self-management behaviour.

Moreover, our results demonstrated that among three types of health literacy, communicative health literacy showed the strongest association to pharmacological management behaviour, but critical health literacy showed the strongest correlation to non-pharmacological management behaviour. The results indicated that the three types of health literacy had different emphasis on their contribution to self-management behaviour. It supported and informed the viewpoint of Heijmans et al.²⁵ The authors believed that critical health literacy was more strongly related to activities that were dependent on individual capacities than to activities that needed the collaboration among patients and health professionals; however, communicative literacy acted in an opposite way.²⁵ Non-pharmacological management behaviour consists of a series of activities that are related to patients’ daily lifestyles (e.g. healthy diet and exercise, non-smoking and abstaining from alcohol) and much emphasis on the individual capability of criticising and exerting useful information into daily practice. Thus, patients with advanced critical health literacy would perform non-pharmacological management behaviour better, while pharmacological management behaviour includes activities (e.g. taking medicines, follow-up consults) that patients need to perform in conjunction with health professionals. Patients with higher communicative health literacy would benefit most from their efficient interaction with healthcare professionals and present higher engagement in pharmacy taking and medical consultation.²⁷ The clinical implications are that targeted self-management support activities based on patients’ health literacy capability should be developed with the participation of family, community and the medical system.

To the best of our knowledge, this is the first study demonstrating the importance of the acceptance of illness as a mediator between health literacy and self-management behaviours in patients with hypertension. That is to say, health literacy was a necessary but insufficient condition for self-management behaviour. The results were partially supported by previous research which reported that the relationships between health literacy and different aspects of self-management behaviour could be mediated by multiple psychosocial factors. As Shin and Lee²⁸ reported, empowerment mediated the relationships between health literacy and self-management behaviours among diabetes patients. In the research of Lee et al., health literacy could influence self-management behaviour by both a direct effect and indirect effect mediated by self-efficacy.²⁹ Our findings for the mediator have also expanded the theoretical mechanisms.

Considering the effects size for the mediation model, functional health literacy influenced pharmacological management behaviour mainly by indirect effects; in contrast, communicative and critical health literacy influenced different aspects of management behaviour mainly by direct effects. According to the Nutbeam model,⁹ three types of health literacy had an ascending level of difficulty and complexity. Functional health literacy refers to basic reading and writing skills. Compared to functional health literacy, communicative and critical health literacy refer to more advanced skills to lead to greater autonomy and empowerment of patients and to a greater role in medical decision-making.^25,30 Thus, communicative and critical health literacy could achieve their facilitation to self-management behaviour mainly by direct effects.

There were still some limitations in the research. First, this was a cross-sectional study and longitudinal research will contribute to provide a more in-depth understanding of the findings in the future. Second, in this research, all the participants were considered to be representative of Chinese patients with hypertension who live in Tianjin City, and they may not be generalised to the overall population in China. A future study should recruit more participants from different regions in China. In addition, too many self-reported questionnaires were used in this research, which might be a heavy burden for participants.

Conclusion

This research demonstrated that health literacy, together with the acceptance of illness, showed positive effects on both pharmacological and non-pharmacological management behaviour. In addition, the acceptance of illness mediated the effects of three types of health literacy on both pharmacological and non-pharmacological management behaviour, although the effect size and pathway differed. Our research highlighted the importance of the acceptance of illness in strengthening the positive effects of health literacy on self-management behaviour. Health literacy and the acceptance of illness should be addressed when taking measures to improve patients’ self-management behaviour.

Acknowledgement

The authors would like to thank all patients as well as their family members who willingly agreed to participate in this study.

Implications for practice

• Patients’ different types of health literacy should be addressed when taking measures to enhance patients’ diverse aspects of management behaviour.

• Acceptance of illness should be addressed when taking measures to improve patients’ self-management behaviour.

• It is important to tailor self-management support activities on patients’ health literacy and acceptance of illness.

Declaration of conflicting interests

The authors declare that there is no conflict of interest.

Ethics approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Declaration of and its later amendments or comparable ethical standards.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: the research was funded by the National Natural Science Fund (71673199 and 71904143) and the Science and Technology Development Fund of Tianjin Education Commission for Higher Education (2017SK097).

References

Author notes