Health locus of control and use of conventional and alternative care: a cohort study

Participants

A prospective cohort study of a representative sample of Japanese households nationwide was analysed. The methodology of this cohort study has been described elsewhere with different aspects of these results published.17 A population-weighted random sample of households controlled for the size of cities, towns, and villages represented, was analysed. Participants were limited to adults aged 18 years and older who filled out a baseline questionnaire and completed a daily health (health diary) and behaviour record, and reported having any pain or symptoms that caused them discomfort during the 31-day study period in October 2003.

Data collection

Health diaries required a daily record for 1 month, from 1 to 31 October 2003. Participants were requested to keep the diary as a record of all health-related events, symptoms, and healthcare utilisation. The aim of the health diary was to elicit responses to the following questions:

• Did you have any pain or other health symptoms that caused discomfort?

• If so, did you consult a physician? Did you use dietary supplements, such as nutritional drinks, vitamins, or calcium? Did you undergo physical treatment, such as acupressure, acupuncture, or massage?

The independent variables of this study were demographic and clinical data and HLCS. One of the dependent variables was the report of symptom-related visits to a physician during the study period, whether to a primary care physician, community hospital, university hospital, or an emergency department. The other dependent variables were self-reported CAM use, which could be either dietary supplements or physical treatments. Any CAM use during the study period after symptom onset was counted as a single positive use per participant, regardless of the frequency of use. The CAM was divided into two major categories:

• Dietary CAM included nutritional drinks, herbs, Kampo (a Japanese herbal medicine), over-the-counter dietary supplements, vitamins and minerals, and other dietary substances.

• Physical CAM included massage, acupuncture, acupressure, Judo-seifuku, moxibustion, and chiropractic and other physical manipulations. Spiritual healing, prayer, shaman, and psychotherapy were excluded from CAM modalities, as these practices were related to control by spiritual or other forces.

The Japanese version of the HLCS was used to determine covariates of interest. This version was developed and validated in the general population in Japan and scored on a Likert scale for each response category. A higher or lower individual score indicated a greater or lesser belief for the health locus of control respectively.

The SF-8™ Health Survey, which measures health-related quality of life, was also included in the questionnaire, as the status of physical and mental health may influence use of health care.18 The SF-8 generates a health profile, consisting of eight scales and two summary measures: a physical summary (PCS8) and a mental summary (MCS8). A higher or lower individual score indicates a better or worse health status than the mean respectively. Lastly, having a designated primary care physician and the number of comorbidities that the participants had were also included as covariates, as these factors may also influence healthcare utilisation.19

Statistical analysis

Descriptive statistics for each of the dimensions of the HLCS and for the use of different types of health care were obtained. Proportions of healthcare use for visiting a physician and dietary and physical CAM along with 95% confidence intervals (CIs) were calculated. These frequencies were also analysed by demographic and clinical characteristics. Three separate multivariable-adjusted logistic regression models were constructed to assess associations between use of the three different types of health care and the covariates, and to calculate adjusted odds ratios (OR) and 95% CIs. Due to concerns with the multiple tests of logistic regressions, ‘significant’ was interpreted only for the association with P-value of less than 0.01 and ‘weak’ for the association with P-value of less than 0.05, but more than 0.01. SPSS software (version 14.0J; SPSS-Japan, Tokyo, Japan) was used for all statistical analyses.

Summary of main findings

In this prospective cohort study based on the daily health record of 2453 participants, 86% developed at least one symptom during the 31-day study period. Of these symptomatic adults, 30% visited physicians, 23% used dietary CAM, and 7% used physical CAM; many used two or more modalities of these healthcare choices. The likelihood of visiting a physician was not significantly influenced by health locus of control. However, the increased use of dietary CAM was weakly associated with beliefs of control by spiritual powers and internal control, and low professional control. Control by spiritual powers was associated significantly with use of physical CAM. To understand CAM use among patients, it may be important to consider an individual's health locus of control as a psychosocial motivation for the use of alternative medicine.20

There are several explanations for the result that the use of dietary or physical CAM was associated with control by spiritual powers. First, some participants with this view are likely to use alternative medicine because they feel that spiritual powers are involved more frequently with this medicine compared with other forms.21^,22 Second, they may believe that it is important to treat illnesses within a non-conventional context using alternative medicine rather than conventional forms based on modern science and technology.21^,22 Finally, some of the participants may have changed their health locus of control toward control by spiritual powers after being involved with a successful experience to treat illness using alternative medicine, and felt that spiritual powers affected the health outcome to a greater degree than other forms of health care.

These findings indicate that the use of dietary CAM slightly increased with high internal control of HLCS, but decreased with high professional control. People with these control views may seek out more CAM, as they consider alternative medicine to be less paternalistic, more empowering, and offering autonomy and control over their healthcare decision-making process.

Strengths and limitations of the study

This study may be the first to analyse the influence of individuals' health locus of control on behaviour related to healthcare utilisation among conventional and alternative medicine. Spiritual modalities were excluded from the CAM modalities in this study; however, it was then shown that the participants with high control by spiritual powers still exhibited a higher likelihood of using dietary and physical CAM.

There were several limitations of the study. First, although it was based on a random, nationally-representative sample, selection bias may have been caused by differences in response rates regarding questionnaires for the HLCS and decreased sample sizes as a result of missing data. A second limitation may be related to data collection for CAM use. A more detailed classification of CAM was not used for specific modalities of physical manipulations. However, most previous studies evaluated CAM therapy combining dietary and physical treatment. Thirdly, although CAM therapy may be more likely to be used for maintenance of health than for treatment of illness,23 the use of dietary and physical CAM was determined to treat symptoms. However, this outcome measure may be better suited to compare the health-related critical decision between conventional and alternative medicine, as this outcome is likely to avoid a bias from baseline of the regular use of CAM among a small proportion of people. Finally, the sample median score of each subscale of the HLCS was used as the estimated approximation of population median score in a Japanese general population with the cut-off scores constructed for a descriptive analysis of this study. The median scores used in this study may not be accurate estimates of population median scores in the general population of Japan.

Comparison with existing literature

Although previous studies have indicated that health locus of control is associated with several health-related behaviours, the results of this study demonstrate that the likelihood of visiting a physician does not differ significantly according to health locus of control. Further, in this study adults with high control by spiritual powers are shown to use dietary and physical CAM more frequently; this confirms the findings of previous studies.16^,24^,25 Moreover, in this study, adults with high internal control use dietary CAM more often, whereas adults with high professional control are less likely to use dietary CAM. These results may be new findings and therefore need further confirmation.

The frequency of symptoms reported in this study (86%) was relatively similar to those in a previous study.26 Green et al showed that among 1000 men, women, and children in the US, 800 (80%) experienced symptoms on average each month.26 In the current study, however, participants were asked to report symptoms that caused ‘discomfort’. Therefore, it is likely that the participants may not have reported minor symptoms. The likelihood of visiting a physician in this study may be higher than that in previous studies.27^–29 A higher frequency for visiting a physician may result from several factors that are specific to Japan, including universal health insurance coverage, ready access to physicians, standardised rates of medical payment, availability of numerous clinics and hospitals, and a relatively low level of income inequality.29^–31 As these backgrounds are related to the conventional healthcare system in Japan, if the Japanese were to become symptomatic, they are likely to visit physicians regardless of each individual's health locus of control.

This study's findings indicate that the use of dietary and physical CAM increase with control by spiritual powers. This may confirm the previous hypothesis introduced by Petry et al.24 The significant predictors for CAM use in the exploratory study by Astin included holistic philosophy, cultural creativity, and transformational experience,16 while those in the study by Testerman et al included holistic beliefs and control by spiritual powers.25 The predictors involved with this dimension in these previous studies are somewhat arbitrary and do not systematically measure all dimensions of individuals' health beliefs.16^,25 However, the HLCS was used as a validated systematic measure for each individual's health beliefs. Further, a natural association between control by spiritual powers and spiritual forms of CAM was excluded by eliminating these CAM forms from the CAM modalities as a dependent variable. Therefore, the methodology used in this study appears to be a powerful tool to demonstrate the association between control by spiritual powers and CAM use compared with the previous studies,16^,25 which may have been biased through the inclusion of a spiritual form of CAM.

Implications for future research

A large proportion of participants used combinations of two or more healthcare modalities including conventional health care as well as alternative medicine. With the increased popularity of alternative medicine, it may be important to understand why a large proportion of people seek approaches that are outside conventional health care. Adults with high control by spiritual powers are more likely to use dietary and physical CAM. Adults with beliefs of high internal control are more likely to use dietary CAM. In contrast, adults with high professional control are less likely to use dietary CAM. Based on the findings of the current study, an individual's health locus of control may be a psychosocial motivation for the use of alternative medicine. Therefore, when assessing an individual's CAM use, it may be important for healthcare practitioners, public health professionals, and policy makers to consider the health locus of control of the these individuals. Individuals' health locus of control is unrelated to the use of conventional health care in this study. Investigation of other reasons for the difference in terms of frequency of seeking conventional health care is needed.