Using the Health Belief Model to Explain Clinic Appointment-Keeping for the Management of a Chronic Disease Condition

Broken appointments have untoward repercussions for patients' health and well-being. Although the literature on missed appointments has been largely atheoretical, several studies have tested the Health Belief Model (HBM) in this context. Those studies have found HBM dimensions are not predictive of keeping appointments for the management of a chronic condition. Given several limitations that characterize these studies, questions can be raised about the validity of this conclusion. This study investigated the utility of HBM for explaining appointment-keeping for Systemic Lupus Erythematosus (SLE), a potentially fatal chronic disease. A questionnaire, operationalizing HBM dimensions and exhibiting acceptable psychometric properties, was developed for this research and administered to 153 SLE patients enrolled at an outpatient clinic of a major teaching hospital. In addition to measuring intention to keep appointments, data were abstracted from medical records regarding actual appointment-keeping during 12 months prior to and 6 months following questionnaire completion. Regression analysis indicated that general health motivation and perceived severity of SLE were uniquely associated in the theoretically predicted direction with, respectively, intent and the percentage of scheduled appointments kept (PSAK) during the 12 month retrospective period. Perceived costs was associated in the expected direction with intent, 12 month retrospective and 6 month prospective PSAK. Typical of HBM research the effect sizes uncovered were modest in magnitude. Questions for future investigation are discussed.     

The health belief model and participation in programmes for the early detection of breast cancer: a comparative analysis

Extravagant claims have been made about the power of the Health Belief Model (HBM) to explain both decisions to adopt patterns of health behaviour and to use preventive health services. However, studies where information on beliefs are collected before information on behaviour are not common. The analyses presented here are based on prospective studies examining how far the variables which make up the HBM predict attendance at (i) a class teaching breast self-examination and (ii) a clinic providing mammography. The results show that different dimensions of the HBM are amongst the best predictors of attendance at each of the different services although the overall variance explained by the HBM in both sets of analysis was small.     

The effect of subject characteristics and respirator features on respirator fit

A recent study was conducted to compare five fit test methods for screening out poor-fitting N95 filtering-facepiece respirators. Eighteen models of NIOSH-certified, N95 filtering-facepiece respirators were used to assess the fit test methods by using a simulated workplace protection factor (SWPF) test. The purpose of this companion study was to investigate the effect of subject characteristics (gender and face dimensions) and respirator features on respirator fit. The respirator features studied were design style (folding and cup style) and number of sizes available (one size fits all, two sizes, and three sizes). Thirty-three subjects participated in this study. Each was measured for 12 face dimensions using traditional calipers and tape. From this group, 25 subjects with face size categories 1 to 10 tested each respirator. The SWPF test protocol entailed using the PortaCount Plus to determine a SWPF based on total penetration (face-seal leakage plus filter penetration) while the subject performed six simulated workplace movements. Six tests were conducted for each subject/respirator model combination with redonning between tests. The respirator design style (folding style and cup style) did not have a significant effect on respirator fit in this study. The number of respirator sizes available for a model had significant impact on respirator fit on the panel for cup-style respirators with one and two sizes available. There was no significant difference in the geometric mean fit factor between male and female subjects for 16 of the 18 respirator models. Subsets of one to six face dimensions were found to be significantly correlated with SWPFs (p < 0.05) in 16 of the 33 respirator model/respirator size combinations. Bigonial breadth, face width, face length, and nose protrusion appeared the most in subsets (five or six) of face dimensions and their multiple linear regression coefficients were significantly different from zero (p < 0.05). Lip length was found in only one subset. The use of face length and lip length as the criteria to define the current half-facepiece respirator fit test panel may need to be reconsidered when revising the panel. Based on the findings from this and previous studies, face length and face width are recommended measurements that should be used for defining the panel for half-facepiece respirators.     

The Effect of Educational Program on Increasing Cervical Cancer Screening Behavior among Women in Hamadan, Iran: Applying Health Belief Model

Background: The systematic application of Pap test helps early diagnosis and effective treatment of cervical cancer. This study was conducted to assess the effect of education on health beliefs and practice of women eligible for Pap test using Health Belief Model (HBM). Methods: This quasi-experimental study was conducted in Hamadan City, the west of Iran, in 2010 using before-after design. In this study, 70 women aged 16 to 54 years participated voluntarily who had never done Pap test until the date of the study. The volunteers were divided into several small groups. For each group, 2-hour training session was held twice. The data collection tool was a self-administered multi-choice questionnaire that was developed based on HBM constructs. Health beliefs and practice of the target group were evaluated pre-intervention and four months later. Results: Our findings indicated that education based on HBM was effective and could enhance the participants' knowledge significantly and improve the HBM constructs including perceived susceptibility, severity, benefits, and barriers. The training program enhanced the practice from zero before intervention to 81.4% after that. The results of the present study revealed that increase in knowledge had effect on the HBM constructs. Furthermore, there was a significant relationship between knowledge and both age and educational level. Conclusion: Health education based on HBM can enhance women's knowledge of cervical cancer, change their health beliefs and improve their behaviors regarding screening programs like Pap test.     

Measurement of motivation for exercise

Motivation for exercise is a theoretically and empirically significant concept that is variously measured in the literature. This paper reviews recent studies that measure motivation for exercise. The findings from 22 studies that met inclusion criteria demonstrate that there is a deficiency in the published literature regarding the establishment of the psychometric properties of reliability and validity. Only five of the 22 studies report both reliability and validity measures on an instrument. An improvement in the reporting of psychometric measures and the utilization of established tools will advance the research and science of exercise motivation. The improvement in study psychometrics has implications for practical application in the field of exercise and the more general category of health promotion.     

Reference values and human biological monitoring values for environmental toxins

This article describes the working principles and working procedures of the Commission on Human Biological Monitoring, which was established in 1993 as a joint commission of the Federal Health Office (Bundesgesundheitsamt) and the Federal Environmental Agency (Umweltbundesamt) in Germany. One of the main tasks of the commission is to develop scientifically based criteria for the application of human biological monitoring and for the evaluation of human monitoring data in environmental medicine. In principle, two different kinds of criteria are recommended: (a) reference values and (b) human biological monitoring values (HBM values). Reference values are intended to indicate the upper margin of the current background exposure of the general population to a given environmental toxin at a given time. Reference values can be used to identify subjects with an increased level of exposure (in relation to background exposure) to a given environmental toxin. However, reference values do not represent health-related criteria for the evaluation of human biological monitoring data. HBM values are derived from human toxicology and epidemiology studies and are intended to be used as a basis for a health-related evaluation of human biological monitoring data. Usually the commission recommends two different HBM values: HBM I, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) below which there is – according to the knowledge and judgement of the commission – no risk for adverse health effects in individuals of the general population; and HBM II, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) above which there is – according to the knowledge and judgement of the commission and with regard to the environmental toxin under consideration – an increased risk for adverse health effects in susceptible individuals of the general population. The HBM I value can be considered a kind of alert value (from the toxicological point of view), whereas the HBM II value represents a kind of action level, at which attempts should be undertaken to reduce the level of exposure immediately and to carry out further medical examinations. Values between HBM I and HBM II should be considered a warning signal of the need to control the analytical measurement and to reduce the level of exposure of the concerned individual as reasonably as is achievable. At present, reference and HBM values are available for lead in blood, for cadmium and mercury in blood and urine, and for pentachlorophenol in plasma/serum and urine. Reference values have been established for some polychlorinated biphenyls in blood and plasma as well as for hexachlorocyclohexane and hexacholorobenzene in blood as well as for some organochlorine in human milk. Received: 19 February 1999 / Accepted: 22 March 1999     

Xiang Study: an association of breastmilk composition with maternal body mass index and infant growth during the first 3 month of life

BACKGROUND/OBJECTIVESThis study aimed to establish a mother and child cohort in the Chinese population, and investigate human breastmilk (HBM) composition and its relationship with maternal body mass index (BMI) and infant growth during the first 3 mon of life.SUBJECTS/METHODSA total of 101 Chinese mother and infant pairs were included in this prospective cohort. Alterations in the milk macronutrients of Chinese mothers at 1 mon (T1), 2 mon (T2), and 3 mon (T3) lactation were analyzed. HBM fatty acid (FA) profiles were measured by gas chromatography (GC), and HBM proteomic profiling was achieved by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS).RESULTSDuring the first 3 mon of lactation (P < 0.05), significant decreases were determined in the levels of total energy, fat, protein, and osteopontin (OPN), as well as ratios of long-chain saturated FA (including C16:0, C22:0 and C24:0), monounsaturated FA (including C16:1), and n-6 poly unsaturated FA (PUFA) (including C20:3n-6 and C20:4n-6, and n-6/n-3). Conversely, butyrate, C6:0 and n-3 PUFA C18:3n-3 (α-linolenic acid, ALA) were significantly increased during the first 3 mon (P < 0.05). HBM proteomic analyses distinguished compositional protein differences over time (P = 0.001). Personalized mother-infant analyses demonstrated that HBM from high BMI mothers presented increased total energy, fat, protein and OPN, and increased content of n-6 PUFA (including C18:3n-6, C20:3n-6 and n-6/n-3 ratio) as compared with low BMI mothers (P < 0.05). Furthermore, BMI of the mothers positively correlated with the head circumference (HC) of infants as well as the specific n-6 PUFA C20:3n-6 over the 3 time points examined. Infant HC was negatively associated with C18:0.CONCLUSIONThis study provides additional evidence to the Chinese HBM database, and further knowledge of FA function. It also helps to establish future maternal strategies that support the healthy growth and development of Chinese infants.     

肝移植随访管理中健康信念模式的建立及前瞻随机对照的临床研究

目的建立肝移植特异性健康信念模式并探讨其对受者生存状况的影响。方法对在我院长期随诊的肝移植受者采取问卷调查的方式获得该群体最关切的健康问题和期望的随访模式，建立肝移植特异性健康信念模式，采取前瞻、随机、对照的研究方式用该模式干预肝移植健康管理和随访过程，观察该信念模式对肝移植受者生存状况的影响。结果（1）共有374人接受问卷调查，肝移植受者所关注的问题集中在随访的意义及合理用药等7个方面，希望通过成立移植之家和强化随访人员角色功能等方式参与随访并进行互动。（2）根据上述调查结果建立肝移植特异性健康信念模式，用该模式对前述接受调查的374例肝移植患者的健康管理和随访过程进行前瞻、随机、对照的干预研究，随诊2年，结果干预组（190例）肝功能异常、感染、原发病复发的发生率分别为16．8％（32／190）、3．2％（6／190）、2．6％（5／190）；对照组（184例）分别为21．2％（39／184）、10．3％（19／184）、9．8％（18／184），差异有统计学意义（P〈0．05）。结论建立肝移植特异性健康信念模式并用于肝移植术后健康管理和随访过程，可明显降低受者不良健康事件的发生率。     

A simple and valid tool distinguished efficacy from effectiveness studies

OBJECTIVE: To propose and test a simple instrument based on seven criteria of study design to distinguish effectiveness (pragmatic) from efficacy (explanatory) trials. STUDY DESIGN: Currently no validated definition of effectiveness studies exists. We asked the directors of 12 Evidence-based Practice Centers to select six studies each: four that they considered to be examples of effectiveness trials and two considered efficacy studies. We then applied our proposed criteria to test the construct validity using the selected studies as if they had been identified by a gold standard. RESULTS: Based on the rationale to identify effectiveness studies reliably with minimal false positives (i.e., a high specificity), a cutoff of six criteria produced the most desirable balance between sensitivity and specificity. This setting produced a specificity of 0.83 and a sensitivity of 0.72. CONCLUSION: When applied in a standardized manner, our proposed criteria can provide a valid and simple tool to distinguish effectiveness from efficacy studies. The applicability of systematic reviews can improve when analysts place more emphasis on the generalizability of included studies. In addition, clinicians can also use our criteria to determine the external validity of individual studies, given an appropriate population of interest.     

An assessment of validity and responsiveness of generic measures of health-related quality of life in hearing impairment

Purpose

This review examines psychometric performance of three widely used generic preference-based measures, that is, EuroQol 5 dimensions (EQ-5D), Health Utility Index 3 (HUI3) and Short-form 6 dimensions (SF-6D) in patients with hearing impairments.

Methods

A systematic search was undertaken to identify studies of patients with hearing impairments where health state utility values were measured and reported. Data were extracted and analysed to assess the reliability, validity (known group differences and convergent validity) and responsiveness of the measures across hearing impairments.

Results

Fourteen studies (18 papers) were included in the review. HUI3 was the most commonly used utility measures in hearing impairment. In all six studies, the HUI3 detected difference between groups defined by the severity of impairment, and four out of five studies detected statistically significant changes as a result of intervention. The only study available suggested that EQ-5D only had weak ability to discriminate difference between severity groups, and in four out of five studies, EQ-5D failed to detected changes. Only one study involved the SF-6D; thus, the information is too limited to conclude on its performance. Also evidence for the reliability of these measures was not found.

Conclusion

Overall, the validity and responsiveness of the HUI3 in hearing impairment was good. The responsiveness of EQ-5D was relatively poor and weak validity was suggested by limited evidence. The evidence on SF-6D was too limited to make any judgment. More head-to-head comparisons of these and other preference measures of health are required.     

Psychosocial work stressors as antecedents of musculoskeletal problems: a systematic review and meta-analysis of stability-adjusted longitudinal studies

Although the relationship between psychosocial workplace conditions and musculoskeletal problems has been extensively studied, the causal impact of psychosocial workplace factors in the development of musculoskeletal problems remains unclear. The purpose of the present study was to conduct a systematic review of baseline-adjusted prospective longitudinal studies estimating the lagged effect of psychosocial risk factors on musculoskeletal problems in industrialized work settings. A literature review was conducted by searching the MEDLINE, EMBASE, and PsychINFO databases dated until August 2009. The authors classified studies into categories of psychological work stressors and musculoskeletal problems. Available effect sizes were converted to odds ratios (OR). ORs were then pooled for each stressor-problem relationship using a random-effects model. Additionally, the possibility of publication bias was assessed with the Duval and Tweedie nonparametric "trim and fill" procedure. In total, 50 primary studies fulfilled inclusion criteria. Within these studies at least five effect sizes were available for 23 of the 45 possible psychosocial work stress-musculoskeletal problems relationships, leaving 9 psychosocial variables and four musculoskeletal problem areas for analyses. Of these 23 relationships, pooled OR estimates were positive and significant ranging from 1.15 to 1.66 with the largest pooled OR estimating the relationship between highly monotonous work and lower back pain. The lagged effect of low social support on lower limb problems was the only effect size for which the statistical test for bias was significant. Most psychosocial stressors had small but significant lagged effects on the development of musculoskeletal problems. Thus, organizational interventions to minimize these stressors may be promising in reducing one risk factor for the development of employee musculoskeletal problems.     

Assessment of diagnostic tests to inform policy decisions--visual electrodiagnosis

OBJECTIVES: To conduct a systematic review of the evidence for the effectiveness of five visual electrodiagnostic tests to inform the Medical Services Advisory Committee (MSAC) of the Department of Health and Ageing (Australia) in its decision in allocating public funding for new technologies. METHODS: We searched the biomedical literature to identify English-language articles published from 1966 to September 2000. We assessed validity of methodology of included studies against the following criteria: investigators (i) compared test with an appropriate reference test; (ii) tested an appropriate spectrum of patients; (iii) masked assessment of study and reference tests; (iv) measured the study test independently of clinical information; and (v) measured the reference test before any interventions. RESULTS: Sixty-one articles met inclusion criteria for critical appraisal: nineteen were cross-sectional studies that compared a study test with another test, thirty-four were case-control studies that compared a test in a group of patients with an eye disease to a group of subjects without eye disease, and eight studies were case series. None of the included studies met all of the validity criteria. Only four studies provided enough information to calculate diagnostic characteristics but were flawed due to inclusion of patients already diagnosed with disease or lack of an appropriate reference test and, thus, overestimated test accuracy. CONCLUSIONS: Identified studies did not provide sufficient valid evidence of the clinical value of the five visual tests in diagnosing diseases of the retina or optic nerve. Thus, MSAC recommended that the tests not be supported by public funding.     

Limited evidence for effects of diet for type 2 diabetes from systematic reviews

OBJECTIVE: Systematic reviews are an appraised method to summarize research in a concise and transparent way, and may enable to draw conclusions beyond the sum of results of individual studies. We assessed the results, quality and external validity of systematic reviews on diet in patients with type 2 diabetes. DESIGN, SETTING, SUBJECTS: We systematically searched for systematic reviews on nutritional interventions in patients with type 2 diabetes that used a reproducible search strategy in at least one major database that applied some form of quality assessment. We assessed quality and the external validity of the retrieved systematic reviews. Outcomes were defined as statistical meta-analyses or narrative results using a predefined and reproducible method. RESULTS: Six systematic reviews met the inclusion criteria, investigating dietary interventions in general (n=3), chromium supplementation (n=1), fish-oil (n=1) or herbs and nutrition supplements (n=1). Quality assessment showed minimal/minor flaws in four cases and major/extensive flaws in two cases. All reviews had insufficient data needed to judge external validity. In reviews with minimal/minor flaws, we found beneficial effects of very-low-calorie diets and fish-oil supplements. However, the external validity of these results could not be assessed sufficiently. CONCLUSIONS: Systematic reviews largely failed to produce knowledge beyond the sum of the original studies. Furthermore, judgment of external validity was hampered in most cases owing to missing data. To improve the quality and usefulness of systematic reviews of dietary interventions, we recommend the application of more focused research questions, but with broader inclusion criteria, for example, the use of observational studies. SPONSORSHIP: Internal funding Radboud University Nijmegen Medical Centre.     

Cultural Dissimilarities in General Practice: Development and Validation of a Patient’s Cultural Background Scale

Due to increased migration physicians encounter more communication difficulties due to poor language proficiency and different culturally defined views about illness. This study aimed to develop and validate a ‘patient’s cultural background scale’ in order to classify patients based on culturally conditioned norms instead of on ethnicity. A total of 986 patients from 38 multi-ethnic general practices were included. From a list of 36 questions, non-contributing and non-consistent questions were deleted and from the remaining questions the scale was constructed by principal component analysis. Comparing the scale with two other methods of construction assessed internal validity. Comparing the found dimensions with known dimensions from literature assessed the construct validity. Criterion validity was determined by comparing the patient’s score with criteria assumed or known to have relationship with cultural background. Criterion validity was reasonably good but poor for income. A valid patient’s cultural background scale was developed, for use in large-scale quantitative studies.     

Reassessment of critical lead effects by the German Human Biomonitoring Commission results in suspension of the human biomonitoring values (HBM I and HBM II) for lead in blood of children and adults

In Germany, the Human Biomonitoring Commission of the Federal Environment Agency continuously assesses environmental pollutants to derive human biomonitoring (HBM) and reference values. HBM values are derived on the basis of toxicological, epidemiological studies or toxicokinetic extrapolation which provides a concentration of a substance or its metabolites corresponding to tolerable intake doses. Two levels are defined: HBM I and HBM II. In 1996, the Commission set a HBM I of 100 μg/l for lead in blood of children ≤12 years and females of a reproductive age and a HBM I of 150 μg/l for the other persons. In the light of findings from epidemiological studies on effects below 100 μg/l, the Commission reevaluated and confirmed the assessment from 1996 in 2002. Meanwhile the general decline in lead pollution has allowed recent studies to include more cohorts with blood lead levels predominantly below 100 μg/l. These data confirm that lead's critical effect, particularly on the developing organism and during early childhood, concerns the nervous system and that negative correlations between blood lead levels and relevant variables (cognitive function, behaviour) occur at blood lead levels below 100 μg/l. The new data also support the possible persistence of lead-induced effects into adulthood. It is not possible to indicate thresholds. Concerning the estimation of the size of the effects, recent studies suggest that lead's influence on development is comparable with other factors influencing development. Furthermore inorganic lead and compounds were classified by IARC in group 2A (probably carcinogenic to humans) and by the German Research Foundation (MAK Commission) in category 2 (to be regarded as human carcinogen). We conclude that any setting of an “effect threshold” for blood lead levels would be arbitrary and therefore unjustified. As a consequence the Commission suspends the HBM values for lead in blood of children and adults.     

The German Human Biomonitoring Commission

In Germany, the Human Biomonitoring Commission of the German Federal Environment Agency was established in 1992 to develop scientifically based criteria for the application of human biomonitoring (HBM). The goal is to clarify fundamental and practical issues related to HBM. Following the assessment of pollutants in body fluids, the commission derives two different kinds of guideline values: reference values and HBM values (HBM I and HBM II values). This article gives a review of the current reference values, HBM values, and the work of the German Human Biomonitoring Commission.     

Test-retest reliability of the GO-QOL: a disease-specific quality of life questionnaire for patients with Graves' ophthalmopathy.

To assess the test-retest reliability of a recently developed disease-specific quality of life questionnaire for evaluative studies in patients with Graves' ophthalmopathy (the GO-QOL), measuring visual functioning and psychosocial consequences of changed appearance. Ninety-three patients were included and completed the GO-QOL. Additional information on general quality of life and disease characteristics was obtained. Construct validity and internal consistency of the two subscales was determined, based on principal component analyses, Cronbach's alpha's and correlations with MOS-24, three subscales of the SIP, and clinical measures. Eighty-nine patients completed a second GO-QOL after two weeks including four additional questions about perceived changes in health status. Test-retest reliability was assessed by calculating intraclass correlation coefficients (ICCs) and limits of agreement, using several definitions of stable patients. Slight modifications from the original questionnaire were evaluated for their effect on the validity and reliability. The construct validity of the two subscales was confirmed and Cronbach's alpha's were 0.89 for visual functioning and 0.87 for appearance. The substantial ICCs found for both scales of the GO-QOL (ICCs above 0.80) reflect that the errors of measurement were relatively small, which supports the value of this questionnaire for clinical studies with relatively small sample sizes. The modification of the appearance scale improved the validity of the scale and resulted in less missing values. Following the recommendations of the joint committee of thyroid associations, we recommend the inclusion of HRQL-measures in clinical studies that evaluate treatments for patients with GO. The GO-QOL is a promising tool for this purpose.     

An update of a systematic review of controlled clinical trials on the primary prevention of back pain at the workplace

OBJECTIVE: To update the evidence on the effectiveness of lumbar supports, education and exercise in the primary prevention of low back pain at the workplace. METHODS: A computerized search for controlled clinical trials published between 1997 and 2002 was conducted, and the methodological quality of the studies was assessed using a criteria list. The available evidence was graded with a rating system for the level of evidence. Effect sizes of individual studies were combined if the studies were sufficiently similar. RESULTS: Five new papers were identified for the update. These trials were added to the previously available trials (n = 11). The methodological quality of most studies was low. Since three of four RCTs on lumbar supports reported no effect, there is no evidence for the effectiveness of lumbar supports. No evidence for education could be found either, since all six RCTs showed negative results. The four RCTs on exercise consistently reported a positive effect, indicating limited evidence for the effectiveness of exercise. CONCLUSION: There is no evidence for the effectiveness of lumbar supports or education in the primary prevention of low back pain at the workplace. There is limited evidence for the efficacy of exercise, and the effect that can be obtained is moderate. There is still a need for methodologically sound studies and studies on the cost-effectiveness of exercise. Also the possible effect of lumbar supports in the treatment of back pain needs further investigation.     

Measuring intermediate outcomes of violence prevention programs targeting African-American male youth: an exploratory assessment of the psychometric properties of six psychosocial measures

This study examined the psychometric properties of six psychosocial measures that may be useful indicators of intermediate outcomes of violence prevention programs targeting African-American male youth. Baseline and 6 month follow-up survey data are used from 223 African-American male 12-16 year olds participating in a violence prevention program evaluation study. The constructs of interest are beliefs supporting aggression, aggressive conflict-resolution style, hostility, ethnic identity, self-esteem and hopelessness. Each construct is measured as a multi-item scale. Exploratory factor analysis results provided limited support for the unidimensionality of these scales, thus suggesting that further scale development is warranted. Reliability coefficients for the scales ranged from 0.55 to 0.80. Bivariate analyses with baseline data indicate that all six measures have construct and criterion-related validity, as they are associated with each other and with four behavioral criteria in the expected directions. Predictive validity was also demonstrated for beliefs supporting aggression, aggressive conflict-resolution style, hostility and hopelessness which were associated with weapon-carrying behaviors measured in the 6 month follow-up survey both before and after controlling for corresponding behaviors measured in the baseline survey.     

Towards an Effective Health Interventions Design: An Extension of the Health Belief Model

Introduction

The recent years have witnessed a continuous increase in lifestyle related health challenges around the world. As a result, researchers and health practitioners have focused on promoting healthy behavior using various behavior change interventions. The designs of most of these interventions are informed by health behavior models and theories adapted from various disciplines. Several health behavior theories have been used to inform health intervention designs, such as the Theory of Planned Behavior, the Transtheoretical Model, and the Health Belief Model (HBM). However, the Health Belief Model (HBM), developed in the 1950s to investigate why people fail to undertake preventive health measures, remains one of the most widely employed theories of health behavior. However, the effectiveness of this model is limited. The first limitation is the low predictive capacity (R² < 0.21 on average) of existing HBM’s variables coupled with the small effect size of individual variables. The second is lack of clear rules of combination and relationship between the individual variables. In this paper, we propose a solution that aims at addressing these limitations as follows: (1) we extended the Health Belief Model by introducing four new variables: Self-identity, Perceived Importance, Consideration of Future Consequences, and Concern for Appearance as possible determinants of healthy behavior. (2) We exhaustively explored the relationships/interactions between the HBM variables and their effect size. (3) We tested the validity of both our proposed extended model and the original HBM on healthy eating behavior. Finally, we compared the predictive capacity of the original HBM model and our extended model.

Methods:

To achieve the objective of this paper, we conducted a quantitative study of 576 participants’ eating behavior. Data for this study were collected over a period of one year (from August 2011 to August 2012). The questionnaire consisted of validated scales assessing the HBM determinants – perceived benefit, barrier, susceptibility, severity, cue to action, and self-efficacy – using 7-point Likert scale. We also assessed other health determinants such as consideration of future consequences, self-identity, concern for appearance and perceived importance. To analyses our data, we employed factor analysis and Partial Least Square Structural Equation Model (PLS-SEM) to exhaustively explore the interaction/relationship between the determinants and healthy eating behavior. We tested for the validity of both our proposed extended model and the original HBM on healthy eating behavior. Finally, we compared the predictive capacity of the original HBM model and our extended model and investigated possible mediating effects.

Results:

The results show that the three newly added determinants are better predictors of healthy behavior. Our extended HBM model lead to approximately 78% increase (from 40 to 71%) in predictive capacity compared to the old model. This shows the suitability of our extended HBM for use in predicting healthy behavior and in informing health intervention design. The results from examining possible relationships between the determinants in our model lead to an interesting discovery of some mediating relationships between the HBM’s determinants, therefore, shedding light on some possible combinations of determinants that could be employed by intervention designers to increase the effectiveness of their design.

Conclusion:

Consideration of future consequences, self-identity, concern for appearance, perceived importance, self-efficacy, perceived susceptibility are significant determinants of healthy eating behavior that can be manipulated by healthy eating intervention design. Most importantly, the result from our model established the existence of some mediating relationships among the determinants. The knowledge of both the direct and indirect relationships sheds some light on the possible combination rules.