A pseudotherapy is considered to be “a substance, product, activity or service with a purported health purpose that does not have support from scientific knowledge or evidence guaranteeing its efficacy and safety” [1]. The use of pseudotherapies is quite accepted in Europe—according to the European Social Survey, Round 7 (edition 2.0, 2014), 25.9% of the general population had used them in the last 12 months [2]. In Spain, their use is also prevalent—despite high levels of trust in conventional medicine and health professionals—ranging between 17.2% in the last 12 months [2] and 19.6% for having ever used them [3]. The sociodemographic profile of the pseudotherapy user in Spain is that of a middle/upper class woman, with higher-level university studies and a progressive political ideology [4]. The use of pseudotherapies can imply genuine health risks because this use is based on misleading advertising about the expected therapeutic effects, and this can favour the delay or substitution of conventional treatments, or even reduce the effectiveness of the latter [1].

Pseudotherapy use has been linked to negative experiences with conventional evidence-based medicine, ranging from a negative doctor-patient interaction to the perception of conventional medicine’s ineffectiveness, through to the side effects of conventional treatments [5–7]. In this way, the use of pseudotherapies would be motivated by being perceived as risk-free, in part because their development has not been influenced by the interests of pharmaceutical companies [8, 9]. However, motivation for pseudotherapy use is not simply derived from a rejection of conventional medicine or a poor perception of health systems [10]. On the contrary, pseudotherapy users are defined as proactive subjects with the ability to choose their treatments [5, 6, 9] and, for this reason, they carry out an individualized search for those types of treatments that they believe will be effective for them [7].

On the other hand, some studies have shown that the use of pseudotherapies is motivated by rejection of science and conventional medicine, especially in relation to the perception of their limitations and side effects [11–13]. However, other studies have suggested that pseudotherapy users have coexisting beliefs in the efficacy of both these and conventional medicine—which is why they use pseudotherapies as complementary treatments [10, 14, 15]. This could be explained by pseudotherapies’ scientific appearance, which is constructed, at least in part, through the way they are presented in the media [10, 16]. The appearance of scientific validity is supported by the recommendations of some doctors and, for pseudotherapies such as homeopathy, they are dispensed in pharmacies together with drugs that have had their efficacy shown scientifically [10].

The objective of the present study was to identify how the following factors have influenced pseudotherapy use in Spain:

- Attitude towards medicine and health and evaluation of the public health system, as well as perceived health.

To do this, we carried out a cross-sectional study of the Survey of Social Perception of Science and Technology 2018 [3] of the Spanish Foundation for Science and Technology (FECYT). This 9th edition of the survey included a question on the use of pseudotherapies for the first time. It also gathered data on the population’s perception of pseudotherapies, and opinions on science and medicine – together with sociodemographic contextual variables.

Of the 5,200 people surveyed, information on pseudotherapy use was obtained from 5,183 (nc = 17). 48.7% of the sample were men and 51.3% women. The prevalence of pseudotherapy use, e.g., homeopathy or acupuncture, at some time in their lives was 19.6%—higher in women than in men (24.9% vs 14.2%, p < 0.001). Of the participants who reported the use of pseudotherapies, 26.3% used them as an alternative therapy and 73.5% as a complementary therapy.

Table 1 describes the prevalence of pseudotherapy use according to the covariates studied. In both sexes, use prevalence is significantly higher in people who answered that they had a high level of interest in and knowledge of medicine and health (Prev_men: 19.7%; Prev_{_}women: 29.9%), in those who have a high confidence in the usefulness of homeopathy and acupuncture Prev_men: 34.1%; Prev_women: 48.2%), as well as in people who perceive that these pseudotherapies have a high level of scientific validity (Prev_men: 23.9%; Prev_women: 37.4%)

In men, use prevalence is significantly higher among those who consider that public health system quality is poor/very poor (16.6%). In women, this prevalence is higher in those who report poor perceived health (Prev_women: 29.9%).

Table 2 shows the variables associated with the use of alternative treatments such as homeopathy or acupuncture. Regardless of the sociodemographic characteristics of the people interviewed, in both sexes the probability of using alternative treatments was greater as confidence in their usefulness for general health and well-being increased (p < 0.001).

In men, use probability increased in those with a medium/high level of knowledge and interest in medicine and health (PR (59% CI): 1.33 (1.09; 1.62)] (ref: low interest), as well as in those who have a negative perception of the quality of the public health system [PR (59% CI): 1.24 (1.01; 1.52)] (ref: positive). In the case of women, the probability of using alternative treatments is greater in those with poor perceived health (PR (59% CI): 1.23 (1.05, 1.42)] (ref: good). The level of scientific validity attributed to homeopathy and acupuncture was not associated with the probability of using alternative therapies, in either sex.

The results of the EPSCYT 2018 analysis show that pseudotherapy-use prevalence at some point in their lives is higher in women (24.9%) than in men (14.2%) and that the probability of using pseudotherapies increases with increasing confidence in their usefulness—regardless of users’ assessment of their scientific validity. Added to this, several factors influence the probability of men and women’s pseudotherapy use: perceived poor health increases this probability in women, while a positive attitude towards medicine and health and a negative assessment of quality of the public health system increases it in men.

As we have indicated, pseudotherapy-use prevalence is higher in women (24.9%) than in men (14.2%). In the full sample, use prevalence at some point during their lives is 19.6%. This data is in line with that obtained in the 2014 European Social Survey for Spain: 17.2% in the last 12 months [2]. The analysis in that survey also shows that the probability of using pseudotherapies is higher in women across the whole sample [2]. For its part, the barometer of the Sociological Research Centre (CIS), which provides data on the use of pseudotherapies in Spain in the last 12 months in a disaggregated manner, shows a homeopathy-use prevalence of 5% [4]. In accordance with our analysis of the EPSCYT 2018, the CIS-survey analysis indicates that the majority of homeopathy users are women (66.1%) [4]. Finally, the analysis of three editions of the National Health Survey (2011, 2014 and 2017) showed a homeopathy-use prevalence in the prior 2 weeks of 1.06%, with higher use-probability in women than in men [18]. The higher prevalence of pseudotherapy use in women could be non-specific since the European Social Survey from 2014 shows that women use primary care and medical specialists more than men, which could be associated with the fact that they also describe a greater unmet need for medical care [19].

The main result of this study is that pseudotherapy use was associated with confidence in their usefulness irrespective of users’ assessment of their scientific validity. Use prevalence is significantly higher in both the people who have high confidence in the usefulness of homeopathy and acupuncture as well as those who perceive that these pseudotherapies have a higher level of scientific validity. However, the multivariate regression model showed that users’ assessment of the therapies’ scientific validity is explained by their confidence in those therapies’ usefulness. Among other causes, this confidence in the usefulness of pseudotherapies may be motivated by an intuitive and uncritical acceptance of the correlation between their use and the perception of efficacy (illusion of causality), which is reinforced by the tendency to selectively remember only the results that lead to improvements [20–22]. Initially, a positive perception of pseudotherapies’ usefulness may arise from exposure to very convincing personal narratives or biased sources such as online forums and social networks, although it can also be derived from the recommendation of medical professionals themselves [6, 22, 23]. But as Atwell et al. suggest, having expectations of the perceived efficacy of pseudotherapies being fulfilled would increase the users’ confidence in their ability to make decisions regarding their health (illusion of control), thus reinforcing the decision to use them again [9]. Recently Ciocănel et al. have shown how the narrative of the apparent efficacy of pseudotherapies like homeopathy is the main justification given by users to legitimize their use [24]. However, the EPSCYT 2018 does not include a question on the satisfaction of previous use of pseudotherapies. This would have been helpful in determining the role of perceived positive experiences in confidence about their usefulness.

On the other hand, use-prevalence is significantly higher in the people who report having a high level of interest in and knowledge of medicine and health, although the multivariate analysis showed that this variable is associated with the use of pseudo-therapies only in men. This result is in line with the results of the analysis of the previous EPSCYT survey, in which a positive association was observed between interest in science and confidence in the effectiveness of pseudotherapies such as homeopathy and acupuncture [10]. Lobera and Rogero-García propose that this association could be explained by appearance of scientific validity pseudotherapies have, based on their presentation as effective medical treatments by the media. In addition, they are recommended by some doctors and, in the case of homeopathy, may be dispensed in pharmacies together with medicines that have been shown to be effective through rigorous scientific testing [10]. In this way, a proportion of pseudotherapy users would maintain belief in the efficacy of both these and conventional medicine, which would lead to the use of pseudotherapies as complementary treatments [10, 14, 15].

Another factor associated with pseudotherapy use in men is the assessment of the quality of the public health system: a poor or very poor assessment was associated with greater use. On the other hand, pseudotherapy use in women was associated with perceived poor health. Various studies have shown that pseudotherapy use can be motivated by negative experiences with conventional medicine, for instance: no improvement in symptoms, poor doctor-patient interaction and treatments’ side effects [6, 7, 24]. This would lead to the search for pseudotherapies as alternative or complementary treatments, especially considering the perception of such treatments as low risk [8, 9, 23]. In addition, pseudotherapy users are defined as active subjects who want to have control over their health and the use of alternative treatments would provide them with a feeling of empowerment [6, 7, 9].

Finally, the results of this study should be taken into account in the implementation of strategies to protect citizens against pseudotherapies [1]. One of these possible strategies would be to disseminate accurate information on pseudotherapies’ effectiveness to both the population and health-related interest groups, based on the “information deficit model” [22]. For these campaigns to be effective, it is important to take into account the psychological factors that induce belief in pseudotherapies’ effectiveness, such as the illusion of causality [20, 25] and the illusion of control [26] and show the mechanisms by which an ineffective intervention can be correlated with apparent efficacy [27, 28]. The cultural factors that help to legitimize pseudotherapies and their use should also be considered, especially narratives about their efficacy [24]. Finally, it is necessary to note the differing factors associated with pseudotherapy-use of in men and women and the higher use prevalence in women [19].