Use of complementary and alternative medicine remedies in Sweden. A population-based longitudinal study within the northern Sweden MONICA Project

Authors


Kjell Asplund Department of Medicine, University Hospital, SE-901 85, Umeå, Sweden (fax: +46 90 14 59 21; e-mail: kjell.asplund@medicin.umu.se).

Abstract

Abstract. Nilsson M, Trehn G, Asplund K (University Hospital, Umeå, Sweden). Use of complementary and alternative medicine remedies in Sweden. A population-based longitudinal study within the northern Sweden MONICA Project. J Intern Med 2001; 250: 225–233.

Objectives. Previous studies have shown a high prevalence of users of complementary and alternative medicine (CAM) remedies in Anglo-Saxon countries. We have explored the use of CAM remedies in Sweden, its distribution in different population groups and time trends during the years 1990–99.

Design and subjects. Within the framework of the population-based northern Sweden Multinational Monitoring of Trends and Determinants of Cardiovascular Disease (MONICA) Project, randomly selected 25–74-year-old participants in risk factor surveys performed in 1990, 1994 and 1999 responded to questions about their use of CAM remedies. The participation rate was 72%.

Results. Amongst 5794 respondents in the 1999 survey, 30.5% reported that they had taken a CAM product (vitamins, minerals or biological CAM remedy) in the preceding 2 weeks. Vitamins/minerals only had been taken by 11.7% and other CAM remedies (dominated by fish oil, ginseng and Q10) with or without vitamins/minerals by 18.8%. Use of CAM remedies was more frequent in women than in men and more frequent in people with high than with low level of education. The prevalence was unrelated to a history of severe cardiovascular disease or diabetes but significantly more common in subjects with poor self-perceived health, particularly so in women. During 1990–99, the use of CAM remedies increased, more in women than in men.

Conclusions. The prevalence of CAM remedy use (other than vitamins and minerals) is high in Sweden. It has been increasing during the 1990s. Its use is particularly common in women, well-educated people and in those with poor self-perceived health.

Introduction

Complementary and alternative medicine (CAM) therapies are widely used in affluent countries such as the USA [1, 2], Canada [3], UK [4], Germany [5] and Australia [6]. In the USA, the total sales of medicinal botanic products was worth close to 4 billion dollars in 1998 [2].

Reasons for the apparent success of CAM remedies that have been identified in scientific studies (for review, see [7]) include: (i) CAM therapists usually devote more time than physicians to each patient and they are often capable of making the patients believe strongly in the therapy they recommend; (ii) many of the CAM therapies emphasize the patient’s empowerment in the healing process, and they usually pay more attention to preventive and salutogenetic aspects than to the pathogenesis of the disease; (iii) many of the powerful therapies used in conventional medicine are associated with risks of severe adverse effects, and many patients want to try first the ‘milder’ remedies that CAM has to offer; (iv) the costs for new conventional drugs are high, often prohibitively high in view of their sometimes marginal effects; some patients want to see if the cheaper CAM alternatives may help instead; (v) there are strong commercial interests and successful marketing of CAM remedies.

Complementary and alternative medicine in the form of herbal medicines, other biological products, vitamins and minerals are taken not only for curative but also for preventive purposes. It seems that less than half of people using CAM therapies do, in fact, have disorders for which they seek cure [8]. In Anglo-Saxon countries, the use is reported to be more frequent in women than in men, more frequent amongst middle-aged than elderly people, and more frequent amongst well-educated than low-educated individuals [8].

To what extent these experiences in Anglo-Saxon populations can be applied to other cultural settings is poorly known. The present survey of CAM is the first one reported in a Scandinavian population, and it is the first longitudinal study performed outside the USA. The study has been restricted to the intake of biological products, vitamins and minerals not prescribed by a physician.

Methods

This study was performed within the framework of the northern Sweden MONICA Project, which, in turn, is part of the World Health Organization (WHO) Multinational Monitoring of Trends and Determinants of Cardiovascular Disease (MONICA) Project [9]. The northern Sweden MONICA study covers the two counties Norrbotten and Västerbotten in northern Sweden with an area of 154 000 km2 and a population of 510 000 persons. In the northern Sweden MONICA Project, cardiovascular risk factors, coronary events and stroke events have been monitored since 1985.

Cardiovascular risk factors are monitored by repeated population surveys amongst 25–74 year-old people. In each sex/10-year age stratum, 250 persons are randomly selected and invited to participate in a screening for cardiovascular risk factors. Such surveys have been performed in the years 1986, 1990, 1994 and 1999. In each survey, a new random sample of the population was invited. In the 1999 survey, all individuals that had been invited to any of the previous surveys and were still living in the area were re-invited. In addition to collecting anthropometric and laboratory data, the invited subjects were asked to complete a questionnaire with questions of potential interest as to cardiovascular disease. We here report data from the 1990, 1994 and 1999 surveys, which included a questionnaire on the use of biological products, vitamins and minerals not prescribed by a physician. The Research Ethics Committee of Umeå University has approved the MONICA risk factors surveys.

In this study, CAM products are defined as minerals, vitamins and other substances not prescribed by a physician (such as Q10, silica, garlic, ginseng, gingko biloba, valeriana, echinacea, fish oil and homeopathic substances). For questions about the use of CAM products, no fixed response alternatives were given. The participants were asked to list all such products they had been using during the last 14 days, including vitamins and minerals.

The cross-sectional part of this study included all people who had been invited to the year 1986, 1990 and 1994 surveys and who participated again in 1999, plus a new cohort investigated in the 1999 risk factor screening. In total, 5794 of 8051 invited participants took part in the 1999 survey and were included in the present study (participation rate 72.1%, Table 1). Questionnaires were sent out to all 2237 nonparticipants to obtain supplementary information on key items. Further attempts were made by telephone interviews to obtain information from those who did not return their questionnaires. As shown in Table 2, when compared with participants, there was amongst nonparticipants a higher proportion of men and a lower proportion of people who were married or cohabitant. Further, the age of the nonparticipants was lower, and self-reported BMI was also lower. The level of education was similar in male participants and nonparticipants, whereas women with a low level of education were over-represented in nonparticipants.

Table 1.   Participants in each MONICA survey, count (%), 25–74-year-old Thumbnail image of
Table 2.   Comparisons of participants and nonparticipants in the Multinational Monitoring of Trends and Determinants of Cardiovascular Disease (MONICA) survey in 1999 (all participants, 25–74-year-old). Data on body mass index (BMI), level of education and marital status available in 47% of the nonparticipants. Values in parentheses are 95% confidence intervals Thumbnail image of

In studies of secular trends, comparisons were made between the participants in the 1990, 1994 and 1999 surveys. The participation rates in the three surveys are shown in Table 1. Because the use of CAM remedies may be different in participants and nonparticipants in population surveys, we compared the CAM use in subject who participated in the 1990 survey and were re-examined in 1999 versus those who attended the 1990 but not the 1999 survey. The proportions of CAM users were 26.2 and 22.6%, respectively. Because of this difference, we included only subjects who were first-time participants in the 1999 MONICA survey in the analysis of time trends between cross-sectional samples, thus omitting those individuals who were re-examined in 1999.

By their responses to the CAM questions, the participants were divided into four categories, one consisting of people who took vitamins and/or minerals only, one who took other CAM substances only, one who concomitantly took both minerals/vitamins and other substances and, finally, one group who took neither. The group of ‘other CAM substances’ is operationally called ‘biological remedies’, because it included not only herbal medicines but also animal products such as fish oil. A very small proportion of users of silica and homeopathy was also included in this group.

Further analyses were done by sex, educational level, medical history of cardiovascular disease or diabetes and self-perceived health. The educational levels were primary school (up to 9 years in school), secondary school (10–12 years) and university level education. The self-reported concomitant disorders recorded were hypertension, stroke, myocardial infarction and diabetes. For assessment of self-perceived health, a five-point Likert scale was used. Levels 1 and 2 were defined as good health, levels 4 and 5 as bad health and level 3 as neither.

The sample size calculations in MONICA were originally based on detection of long-term trends in population levels of classical cardiovascular risk factors. With a minimum of 210 individuals in a subgroup, as in the present study, there is, at a statistical significance of < 0.05 and with an 80% power, a possibility to detect at least a 13% point difference in the prevalence of CAM use between groups when 20% in the low-prevalence group are CAM users.

Statistical methods

For each of the surveys 1990, 1994 and 1999, the proportions of participants using different CAM products were derived and the 95% confidence intervals (CI) were calculated using normal approximation. Age together with level of education, medical history and self-perceived health were included in logistic regression models, and the fitted models were then used to estimate the prevalence in each population group, adjusted to the median age group, 45–54 years.

The use of CAM remedies was further analysed by multiple logistic regression, including the independent variables age, level of education, medical history and self-perceived health. The changes in CAM use over time were analysed using a similar model, in which year of survey was added in the model. Men and women were analysed separately.

To avoid assumptions concerning linearity, all independent variables in the logistic regression models were categorized. In the analysis of secular trends in the use of CAM, only participants between 25 and 64-year-old and, in the survey 1999, only the new cohort was used. The data were analysed in the SPSS statistical program.

Results

There were 5794 participants (2974 women and 2820 men) that reported their CAM use. Of these, 1767 (30.5%) reported that they had taken any CAM product in the last 14 days. The most frequent consumption pattern was the concomitant use of biological remedies and vitamin/mineral supplements (13.7%), followed by vitamins/minerals only (11.7%) and other CAM remedies only (5.1%).

Amongst the CAM products other than vitamins and minerals, fish oil (7.0%), ginseng (3.4%) and Q10 (2.1%) were the most commonly used. Other specified remedies, used by 2.0–0.5% of the respondents, were (in descending order) garlic extracts, silica, echinacea and Ginkgo biloba. Homeopathy was rarely used (0.2%). The diversity of CAM products used more seldom was great and, in total, 173 different CAM preparations were recorded.

Overall, there was no overt relationship between age and use of CAM products (Table 3). Nevertheless there was, in men, an apparent increase in the use of remedies other than vitamins and minerals with increasing age (prevalence 10.4%, 95% CI 6.4–14.5% in the youngest versus 17.3%, 95% CI 14.5–20.1% in the oldest age group). On the other hand, the use of vitamin and/or mineral supplements was significantly higher in 25–34-years-old men than in some of the other age groups (Table 3). In women, no consistent age-related pattern emerged (Table 3). In each age group, a significantly higher proportion of women reported CAM drug use compared with men (Table 3).

Table 3.   Use of CAM products (a) in men and (b) in women by age. The 95% confidence intervals (CI) are estimated by normal approximation Thumbnail image of

People with university level education used all types of CAM products (vitamins/minerals as well as biological remedies) more often than other people. These differences were statistically significant, they were apparent in both sexes and they persisted after age adjustment (Table 4).

Table 4.   Use of CAM products (%) (a) in men and (b) in women by level of education, medical history and self-perceived health. Figures within parentheses are age-adjusted to the median age group, 45–54 years Thumbnail image of

The pattern of CAM use was nearly identical in people with and without a medical history of cardiovascular disorder (hypertension, stroke, myocardial infarction) or diabetes (Table 3). Of all people taking any CAM product, 30.4% reported a history of cardiovascular disease or diabetes whereas 69.6% did not.

In contrast to the medical history, self-perceived health/illness clearly influenced the use of CAM products, particularly so in women (Table 3). Whereas the consumption of vitamin and mineral supplements did not differ, other CAM remedies were used more often by women who perceived their health as poor when compared with those who considered their health to be good (17.0 vs. 12.7% in men; > 0.05 and 28.1 vs. 20.9% in women; < 0.05). Of all people taking any CAM product, 7.6% reported their health to be poor whereas 22.5% reported it to be good and 69.9% neither good nor poor.

Logistic regression models were used to identify independent determinants of CAM use. Separate models were used for biological remedies, vitamin and/or mineral supplements and all CAM remedies together. In men, level of education was the only statistically significant independent predictor of CAM use (Table 5) whereas, in women, both a high level of education and poor self-perceived health predicted a high prevalence of CAM use (Table 5). In women, the higher prevalence in the 55–64 years compared with other age groups was also statistically significant. The presence of cardiovascular disease or diabetes seemed to be unrelated to the use of CAM remedies. These analyses were based on data from the year 1999 survey. The sample sizes in the 1990 and 1994 surveys were smaller and hence the statistical power was lower. Nevertheless, the same associations were seen in logistic regression models, and they reached statistical significance for men in 1990 and women in 1994 (data not shown).

Table 5.   Use of all CAM products (a) in men and (b) in women output from multiple logistic regression. The reference group is given in parentheses in the left column Thumbnail image of

Secular trends in the use of CAM remedies

As shown in Fig. 1, there was a similar secular trend in men and women over the years 1990–99. Whereas the use of vitamins and/or minerals as food supplements remained constant over time, the use of other CAM remedies increased, particularly so in the years 1990–94. Over the 9-year observation period, the prevalence of CAM use (including vitamins and minerals) increased slightly from 17.2 to 21.4% in men (P=0.11) but more strongly in women from 32.5 to 42.0% (P=0.001).

Figure 1.

 Secular trends in the use of CAM remedies, as recorded in 25–64 year-old participants in the northern Sweden MONICA population surveys in 1990, 1994 and 1999.

Discussion

The definition of CAM and CAM therapies is by no means straightforward [10]. We have defined CAM remedies as drugs or natural products that are not prescribed by Swedish physicians and for which there is no consensus in the medical community that there is a medical indication. This means that also vitamin and mineral supplements not prescribed by doctors are included. Randomized controlled trials have failed to show any preventive effects of such products against common serious disorders such as cancer and cardiovascular disorders [11–13]. These food supplements are generally not prescribed by doctors and are not reimbursed by the health insurance system in Sweden. For the sake of simplicity, homeopathy and preparations that are not necessarily biological, such as silica, have been included in the group of biological CAM remedies. Such therapies represent only a small fraction (<5%) of all products in this group.

In a recent systematic review, Ernst identified four major methodological problems in studies that have estimated the prevalence of CAM use [8]: (i) they have often been dealing with CAM in general rather than with the use of specific CAM therapies, mixing for instance acupuncture with aromatherapy and intake of vitamins; (ii) many studies have not been population-based; (iii) they have failed to make both point estimates and measure 1-year prevalence of CAM use; (iv) the response rates have sometimes been inadequate. Harris and Rees [14] encountered the same problems when they recently performed a systematic literature review on the prevalence of CAM use in the general population.

The present study has overcome most of these potential methodological flaws. It was restricted to the use of herbal medicines and other biological CAM remedies (in a broad sense) and vitamin and minerals as food supplements. Our study was truly population-based with a satisfactory response rate that was better than in most previous studies of CAM use [4, 8, 14]. It is, however, based only on a point estimate. Some people apply CAM methods only when they have been afflicted by an acute illness, such as a common cold. A point estimate probably reflects the use of CAM for preventive purposes rather than for acute illness. It underestimates the proportion of people who occasionally use CAM products. On the other hand, it gives the actual prevalence and, by asking for CAM use during the last 2 weeks, recall bias is minimized.

The use of CAM remedies may be part of a healthier than average lifestyle [7, 8] and a willingness to participate in population risk factor surveys like the ones reported here. In support of this notion, CAM use was somewhat more frequent amongst those who had been screened in 1990 and agreed to participate again in 1999 compared with those who did not (see Methods). It may, therefore. be the prevalence rates reported here are higher than the true prevalence in the entire population. Because of the high participation rates, however, the influence of lower CAM use in nonparticipants would be very modest.

The prevalence rates reported here should be compared with what has been observed in other countries. First, the infrequent use of homeopathy in Sweden (<1%) is apparent. Surveys in other countries have reported prevalence rates for homeopathy as high as 12% in Austria [15], 3–6% in the USA [1, 2] and 4% in Australia [6]. On the other hand, the use of herbal medicines seems to be lower in Sweden (point estimates 10–15% in men and 20–25% in women) than in the UK (approx. 35% in the last years) [4] but as common as what point estimates in the USA (12–25%) [2, 16–18] and Australia (10%) [6] have shown. A small US survey, not strictly population-based, has indicated that as much as 40% of people enrolled in a health maintenance organization have ever used herbal remedies [19]. The use of vitamin and/or mineral supplements varies markedly between different populations and over time, ranging from 3% in a Finnish middle-aged population in the late 1970s [20] to half of elderly people in the USA in mid-1990s [21]. This is to be compared with 15–20% of men and more than 30% of women in the present study taking vitamins and/or minerals as food supplements.

Even if the prevalence of CAM use may differ, the distribution amongst population groups seems to follow a common pattern in affluent countries, as confirmed in this study. Women use CAM therapies more often than men and well-educated people more often than people with less education do [8, 14].

In men, use of vitamins and minerals was particularly common in the 25–34 years age group. It thus seems that that groups at particularly low risk of severe illness make up a large share of the users of CAM remedies. This may reflect particular awareness of health issues and disease prevention by these groups, even if the scientific evidence for most CAM products is lacking. The marked discrepancy between observational studies and randomized controlled trials as to the benefits of antioxidant vitamins as food supplements to prevent cancer and cardiovascular disease [11–13] points in the same direction. People who take CAM remedies, including vitamin and mineral supplements, are likely to be more health-conscious and to have a more healthy lifestyle than people who do not take such remedies, but in randomized trials these substances have no protective effects [11–13].

Subjects with a history of cardiovascular diseases or diabetes did not take CAD remedies more often than people without such disorders. On the other hand, self-perceived health was a fairly strong independent predictor of CAM consumption in women (but less so in men). It may be that, in this group, there are women who do not feel that their problems have been sufficiently appreciated by the conventional health care system. It may also be that many subjects with poor self-perceived health have diseases not recorded in the present study, which was focused on cardiovascular disease and its determinants.

Our results show that, during the 1990s, there was a significant increase in the prevalence of CAM remedy consumers in Sweden. The increase was greater amongst women than amongst men. Only one longitudinal study of the use of CAM remedies has been published previously. It showed a marked increase in the prevalence of herbal medicine users, from 2.5 to 12.1% in the USA during the years 1990–97 [2].

In conclusion, this strictly population-based study of 25–74-year-old people in Sweden has shown a very high prevalence of intake of CAM remedies – herbal medicines as well as other biological CAM products, vitamins and minerals. As in other affluent countries, the use of CAM remedies is particularly high in well-educated women. We observed no major influence of age or a history of cardiovascular disease or diabetes on CAM use, but, in women, poor self-perceived health was clearly associated with a higher than average consumption of CAM remedies.

For the conventional health care system, these findings have several implications. The most important is perhaps that, in view of the high prevalence of CAM use, adverse effects and possible interactions with therapies prescribed by physicians must be taken into consideration. Our observations may also signal that people with poor self-perceived health are managed less-than-optimal in the health care system and that they often resort to the use of CAM therapies instead. This is important because self-perceived health is a very strong determinant of future severe disorders, including myocardial infarction [22].

Acknowledgements

This study was supported by grants from the Swedish Medical Research Council (grant no. 27X-07192 to KA), the Heart and Chest Fund, King Gustaf V’s and Queen Victoria’s Foundation, Västerbotten and Norrbotten County Councils, and the Swedish Public Health Institute.

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