Abstracts

Introduction

The term “complementary medicine” refers to a broad set of health care practices, which are outside the traditional or conventional medicine in a given country, and only partially integrated into its dominant healthcare system. Traditional and complementary medicine merges the terms “complementary medicine” and “traditional medicine”, encompassing products, practices, and practitioners, and is used interchangeably with traditional medicine in some countries ¹1. World Health Organization. WHO global report on traditional and complementary medicine 2019. https://apps.who.int/iris/handle/10665/312342 (accessed on 25/Jun/2021).
https://apps.who.int/iris/handle/10665/3... .

In Brazil, Tesser & Luz ²2. Tesser CD, Luz MT. Uma categorização analítica para estudo e comparação de práticas clínicas em distintas racionalidades médicas. Physis (Rio J.) 2018; 28:e280109. developed the analytical category called “medical rationalities” to investigate and compare complex medical systems. A care/healing system is considered a “medical rationality” if such system enables the identification and description of six constituent, coherent, and mutually articulated dimensions can be identified and described in this system, i.e., a medical doctrine (general conceptions and explanations about life, health, illness, and healing), a vital dynamics (equivalent to physiology, in biomedicine), a morphology (or anatomy, in bioscience), a diagnostic system, and a therapeutic system. A worldview or cosmology permeates these five dimensions, which is the its sixth underlying dimension. Through this categorization, it is possible to research and recognize biomedicine, homeopathy, traditional Chinese medicine, anthroposophic medicine, and Ayurvedic medicine as a medical rationality ²2. Tesser CD, Luz MT. Uma categorização analítica para estudo e comparação de práticas clínicas em distintas racionalidades médicas. Physis (Rio J.) 2018; 28:e280109..

Since 2018, 170 World Health Organization’s (WHO) member States acknowledged their use of traditional complementary integrative medicine (TCIM), and 97 of these countries had a national policy ¹1. World Health Organization. WHO global report on traditional and complementary medicine 2019. https://apps.who.int/iris/handle/10665/312342 (accessed on 25/Jun/2021).
https://apps.who.int/iris/handle/10665/3... . In Brazil, TCIM is known as integrative and complementary practices. The Brazilian Unified National Health System (SUS) regulated and implemented these practices in 2006 ³3. Ministério da Saúde. Portaria nº 971, de 3 de maio de 2006. Aprova a Política Nacional de Práticas Integrativas e Complementares (PNPIC) no Sistema Único de Saúde. Diário Oficial da União 2006; 4 may.. The SUS is a free and universal public health system which offers low and high-complexity medical assistance in all regions of the country, covering the demands for medical and hospital care of 70% of the Brazilian population ⁴4. Instituto Brasileiro de Geografia e Estatística. PNS - Pesquisa Nacional de Saúde. https://www.ibge.gov.br/estatisticas/sociais/saude/9160-pesquisa-nacional-de-saude.html?=&t=resultados (accessed on 26/Jun/2021).
https://www.ibge.gov.br/estatisticas/soc... .

TCIM includes several practices with greatly varying prevalence use between countries. The most common form of TCIM practices are acupuncture, herbal medicines, traditional Chinese medicine, and homeopathy. Nevertheless, regulation of TCIM providers is much less common among WHO member States. For example, only 22 member States regulate homeopathy providers ¹1. World Health Organization. WHO global report on traditional and complementary medicine 2019. https://apps.who.int/iris/handle/10665/312342 (accessed on 25/Jun/2021).
https://apps.who.int/iris/handle/10665/3... . Moreover, we find great controversy about the effectiveness of homeopathic treatment. On one hand, homeopathy is considered a complementary practice to the conventional disease-focused and technology-based medical model. On the other hand, a recent review reported that the clinical effects of homeopathy derive from the placebo effect, even though it may be used to treat certain medical conditions ⁵5. Antonelli M, Donelli D. Reinterpreting homoeopathy in the light of placebo effects to manage patients who seek homoeopathic care: a systematic review. Health Soc Care Community 2019; 27:824-47.. This “scientific discussion” has failed to stop people in different countries from opting for this complementary medical practice. On the contrary, homeopathy seems to be popular in countries such as India, France, and the United Kingdom. As a matter of fact, the debate about their effectiveness has failed to precluded several countries from including homeopathy in their publicly funded healthcare systems, of which the United Kingdom, France, Italy, Germany, Switzerland, India, Pakistan, Brazil, and Mexico are the most important examples ⁶6. World Health Organization. Essential Medicines and Health Products Information Portal. https://digicollections.net/medicinedocs/#p/home (accessed on 31/Oct/2021).
https://digicollections.net/medicinedocs... .

The literature has few population-based studies assessing the prevalence of homeopathy use and its associated factors. Overall, homeopathy use varies greatly between countries, with the highest prevalence seen in Switzerland (8.2%), which covers homeopathy in its compulsory health insurance ⁷7. Klein SD, Torchetti L, Frei-Erb M, Wolf U. Usage of complementary medicine in Switzerland: results of the Swiss Health Survey 2012 and development since 2007. PLoS One 2015; 10:e0141985.. United States, United Kingdom, Australia, and Canada show lower rates, ranging from 0.2% to 2.9% ⁸8. Relton C, Cooper K, Viksveen P, Fibert P, Thomas K. Prevalence of homeopathy use by the general population worldwide: a systematic review. Homeopathy 2017; 106:69-78.. In Brazil, two studies used the National Survey of Health (PNS 2013) and found a 0.6% prevalence of homeopathy use in the previous 12 months among Brazilian adults ⁹9. Boing AC, Santiago PHR, Tesser CD, Furlan IL, Bertoldi AD, Boing AF. Prevalence and associated factors with integrative and complementary practices use in Brazil. Complement Ther Clin Pract 2019; 37:1-5.^,1010. Boccolini PMM, Boccolini CS. Prevalence of complementary and alternative medicine (CAM) use in Brazil. BMC Complement Med Ther 2020; 20:51.. Boccolini & Boccolini ¹⁰10. Boccolini PMM, Boccolini CS. Prevalence of complementary and alternative medicine (CAM) use in Brazil. BMC Complement Med Ther 2020; 20:51. also evaluated the relation between different types of TCIM therapy (including homeopathy) and respondents’ sociodemographic characteristics, finding a great heterogeneity regarding the types of TCIM practices participants used, by participants with different characteristics and from different socioeconomic strata across Brazilian regions. According to their socioeconomic status, subjects from upper classes living in Southern Brazil had higher chances to use acupuncture and homeopathy, than individuals from other socioeconomic classes and less developed regions of the country ¹⁰10. Boccolini PMM, Boccolini CS. Prevalence of complementary and alternative medicine (CAM) use in Brazil. BMC Complement Med Ther 2020; 20:51..

Another aspect is the association between poorer self-perceived health and poorer psychological health, which are closely related to any type of TCIM use, including homeopathy treatment. Research has found mixed data about this relation when it considered different TCIM types together. A narrative review ¹¹11. Bishop FL, Lewith GT. Who uses CAM? A narrative review of demographic characteristics and health factors associated with CAM use. Evid Based Complement Alternat Med 2010; 7:11-28. found no strong evidence for the stereotypical belief that those who seek TCIM treatments have higher psychological morbidity. In contrast, a cross-sectional population-based survey from 32 countries found that poor or fair health status, unhappiness and depression were associated with TCIM use ¹²12. Peltzer K, Pengpid S. Prevalence and determinants of traditional, complementary and alternative medicine provider use among adults from 32 countries. Chin J Integr Med 2018; 24:584-90.. If evaluated by itself, a similar controversy about the relation between mental health status and homeopathy treatment arises. A study conducted in the United States found no significant difference in the prevalence of homeopathy use among older adults with and without self-reported anxiety or depression ¹³13. Grzywacz JG, Suerken CK, Quandt SA, Bell RA, Lang W, Arcury TA. Older adults' use of complementary and alternative medicine for mental health: findings from the 2002 National Health Interview Survey. J Altern Complement Med 2006; 12:467-73.. On the other hand, a French study assessed which patient characteristics are associated with a lifetime use of homeopathic treatment for psychiatric symptoms among a sample of 36,785 persons, finding that homeopathy users were 2.5 times more likely to show amood disorders and nearly three times more likely to suffer from anxiety disorders than persons who did not take psychotropic drugs ¹⁴14. Grolleau A, Bégaud B, Verdoux H. Characteristics associated with use of homeopathic drugs for psychiatric symptoms in the general population. Eur Psychiatry 2013; 28:110-6..

This study aims to estimate the prevalence of homeopathy use among a population-based sample of Brazilian adults. Additionally, we aim to assess the association of self-perceived health status, depression, and sociodemographic risk factors with homeopathy use.

Material and methods

Design and sample

Data from the PNS 2019, carried out from August 2019 to March 2020, were used. PNS uses a multi-stage clustered sample. Its first stage consisted of a simple random selection of census tracts from the 2010 Demographic Census (its primary sample units), of which small and special tracts, such as barracks and long-term institutions, were excluded. The second and third stages of the survey performed a simple random selection of (a) households (secondary sample units) and (b) persons aged 15 years or above who lived in those houses (tertiary sample units). The expected sample size (108,255 households), considering a 20% of non-response rate, guarantees an 80% statistical power and precise health indicator estimates. Data were collected via interviews conducted by trained interviewers by a questionnaire inserted in a mobile data collection device. Further details on PNS 2019 have been published ¹⁵15. Stopa SR, Szwarcwald CL, Oliveira MM, Gouvea ECDP, Vieira MLFP, Freitas MPS, et al. National Health Survey 2019: history, methods and perspectives. Epidemiol Serv Saúde 2020; 29:e2020315.. PNS 2019 aimed to provide Brazil with information on the Brazilian population’s health determinants and needs ¹⁵15. Stopa SR, Szwarcwald CL, Oliveira MM, Gouvea ECDP, Vieira MLFP, Freitas MPS, et al. National Health Survey 2019: history, methods and perspectives. Epidemiol Serv Saúde 2020; 29:e2020315.. The questionnaire had three parts, covering (i) household characteristics; (ii) data about on all residents, especially on socioeconomic and health factors; and (iii) information about the selected resident (aged 15 years or above), focusing especially on lifestyle, chronic diseases, violence, among other topics. For our analyses, participants aged between 15 and 107 years, who answered the Selected Resident Questionnaire of PNS, were selected. Thus, data from a sample of 90,846 persons, interviewed in the PNS 2019, were assessed.

Main outcome variable

The following questions from PNS 2019 were used to assess our main outcome. The first question was “Over the past 12 months, did you treat yourself with an integrative and complementary practice, such as acupuncture, homeopathy, medicinal plants, and phytotherapy, among others?”. Possible answers were “yes” or “no”. Participants who gave a positive answer were also asked “What type of treatment did you use?”. Only participants who answered “homeopathy” were analyzed in this study.

Covariates

On the basis of the PNS 2019 questionnaire data, the following sociodemographic factors were assessed: gender (male or female); age (15/34; 35/53; 54/105 years old); self-reported skin color (other or white); living with a partner (yes or no); living area (rural or urban); years of schooling (up to 8; 9 to 11; 12 or more); region of residence (North/Northeast/Central-West or South/Southeast); private health insurance (no or yes); and household monthly income per person, according to the Brazilian minimum wage in quartiles (1 minimum wage = USD 242.20) (0 to ≤ 1/2; > 1/2 to ≤ 1; > 1 to ≤ 2; > 2). The household monthly income per person was estimated by dividing family income by the number of persons living in the household. Information about the self-perceived health status was also collected and classified as: very good/good; regular or poor/very poor. Data on payments for homeopathy treatment were also collected. In total, two questions: “Did you pay anything for this treatment?”; and “Was this treatment provided by the Unified Health System (SUS)?”, were used to evaluate the source of funding tofor the homeopathic treatment. Possible answers for these questions were: no; yes and no; yes, partially; yes, completely, respectively.

Patient Health Questionnaire-9

The Patient Health Questionnaire-9 (PHQ-9), a screening tool for depression which enables diagnosis (according to the Diagnostic and Statistical Manual of Mental Disorders - DSM-IV - criteria for depressive disorder), was answered by all participants. This instrument assesses the presence and intensity of nine items in the two weeks preceding the interview. Scores range from 0 (“not once”) to 3 (“almost every day”) and total scores can range from 0 to 27. Scores of 10 or more are considered cases of major depression ¹⁶16. Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med 2001; 16:606-13.. In total, three categories of depression were used: no depression (score < 10), mild-moderate depression (score 10-14), and moderate-severe depression (score > 14). Cronbach’s alpha was used as our reliability coefficient, totaling 0.84 for PHQ-9 total scores ¹⁷17. Woldetensay YK, Belachew T, Tesfaye M, Spielman K, Biesalski HK, Kantelhardt EJ, et al. Validation of the Patient Health Questionnaire (PHQ-9) as a screening tool for depression in pregnant women: Afaan Oromo version. PLoS One 2018; 13:e0191782..

Statistical analysis

Descriptive analysis was performed. All variables were categorized. Logistic regression models were built to obtain crude and adjusted odds ratio (OR) and 95% confidence intervals (95%CI) for the association between our explanatory variables and homeopathy use. Covariates were identified a priori based on previous research on homeopathy use. All variables (sociodemographic, self-perceived health status, and depression score) were included in our adjusted multivariate model. Statistical analysis was performed via Stata 16 (https://www.stata.com) and its svy command. All estimates were weighted to account for the PNS 2019 complex survey design and to make the estimates nationally representative (weighted pooled N = 168,426,190).

Ethical considerations

Ethical approval and participation consent for the PNS 2019 were granted by the Brazilian National Health Ethics Committee (CONEP; process n. 3,529,376). Participation was voluntary and informed consent forms were signed by all participants. The questionnaire could be completely or only partially answered. The PNS dataset is publicly available on the Brazilian Institute of Geography and Statistics (IBGE) website and its information, anonymized.

Results

We found, in the PNS 2019 data set, 90,846 participants with complete information about their use of homeopathy. The data set lacked 32 missing pieces of informations about on self-reported skin color (10) and family income (22). In the survey, 52.9% of the participants were women, 42.9% were white, 58.3% had a partnered status, and 33.3% were 52 years or older. The average age was 46.2 (SD = 17,5; range 15 to 105). Regarding socioeconomic status, 43.1% attended completed elementary school and more than half (52.3%) had a monthly income per capita of one Brazilian minimum wage or less. Most lived in urban areas (85.9%) and approximately 58% lived in the more developed regions of Brazil (South/Southwest). Nearly one-fourth (26.6%) of participants had private health insurance (Table 1). We found a 0.99% prevalence of homeopathy use in our sample (95%CI: 0.98-1.0). Among participants who were being treated with homeopathic treatment, 78.6% (95%CI: 75.0-81.7) reported paying for it and 94% (95%CI: 91.4-95.8), reported that SUS did not provide it. Only 2.9% (95%CI: 1.8-4.8) of homeopathy users reported that SUS provided them with such treatment.

We found a higher use of homeopathy among white (1.5%), women (1.3%), aged 52 or older (1.1%), with tertiary education (2.9%), highest monthly income per capita (2.8%), who lived in urban areas (1.3%) in more developed regions (1.3%), with private health insurance (2.2%), and a PHQ-9 score greater than 14 (1.9%) (Table 2).

In our bivariate analysis, the following variables were associated with increased use of homeopathy: female gender (OR = 2.37; 95%CI: 1.81-3.10), age between 34 and 51 years old (OR = 1.45; 95%CI: 1.05-2.00) or 52 years or older (OR = 1.68; 95%CI: 1.20-2.34), white skin color (OR = 3.21; 95%CI: 2.46-4.17), completed secondary (OR = 2.14; 95%CI: 1.47-3.11) or tertiary education (OR = 9.72; 95%CI: 7.12-13.2), having up to one (OR = 1.99; 95%CI: 1.08-3.66), up to two (OR = 3.65; 95%CI: 2.10-6.37) or more than two Brazilian minimum wages (family income per capita) (OR = 13.60; 95%CI: 8.20-22.60), having private health insurance (OR = 4.50; 95%CI: 3.44-5.90), residence in urban areas (OR = 3.64; 95%CI: 2.48-5.35), in Southern/Southeastern Brazil (OR = 3.45; 95%CI: 2.73-4.35), and scoring between 10 and 14 in the PHQ-9 (OR = 2.05; 95%CI: 1.34-3.13) or a PHQ-9 score above 14 (OR = 2.38; 95%CI: 1.51-3.75) (Table 3). In our adjusted analysis, the following variables were independently associated with higher use of homeopathy: being female gender, age above 51 years, white skin color, having the highest family income per capita (more than two Brazilian minimum wages), completed secondary or tertiary education, residence in Southern/Southeastern Brazil, poorer self-perceived health status, and a PHQ-9 score between 10 and 14 or above 14 (Table 3). The variable related to having private healthcare was marginally associated with homeopathy use (Table 3).

Discussion

Our findings showed that homeopathy use is very low (0.99%) in Brazil and it is associated with certain demographic and health status characteristics, such as higher socioeconomic and educational status, being the female gender, self-reporting as beingwhite, being older than 51, living in an urban areas, living in Southern/Southeastern Brazil, poorer self-perceived health status, and depression.

Regarding homeopathy use prevalence, studies employed several assessment methods, including over-the-counter (OTC) purchase of homeopathic products and visiting or beingreceiving treatment from a homeopath ⁷7. Klein SD, Torchetti L, Frei-Erb M, Wolf U. Usage of complementary medicine in Switzerland: results of the Swiss Health Survey 2012 and development since 2007. PLoS One 2015; 10:e0141985.^,88. Relton C, Cooper K, Viksveen P, Fibert P, Thomas K. Prevalence of homeopathy use by the general population worldwide: a systematic review. Homeopathy 2017; 106:69-78.^,1818. Cooper KL, Harris PE, Relton C, Thomas KJ. Prevalence of visits to five types of complementary and alternative medicine practitioners by the general population: a systematic review. Complement Ther Clin Pract 2013; 19:214-20.. Some studies assessed a nationally representative sample ⁷7. Klein SD, Torchetti L, Frei-Erb M, Wolf U. Usage of complementary medicine in Switzerland: results of the Swiss Health Survey 2012 and development since 2007. PLoS One 2015; 10:e0141985.^,1919. Dossett ML, Davis RB, Kaptchuk TJ, Yeh GY. Homeopathy use by US adults: results of a national survey. Am J Public Health 2016; 106:743-5. whereas others used a convenience sample ²⁰20. Steinsbekk A. Families' visits to practitioners of complementary and alternative medicine in a total population (the HUNT studies). Scand J Public Health 2010; 38(5 Suppl):96-104.. These differences may explain the large variation of homeopathy use seen among studies. Klein et al. ⁷7. Klein SD, Torchetti L, Frei-Erb M, Wolf U. Usage of complementary medicine in Switzerland: results of the Swiss Health Survey 2012 and development since 2007. PLoS One 2015; 10:e0141985. analyzed data from the Swiss Health Surveys 2007 and 2012 (N = 14,432 and 18,357, respectively) for people aged 15 years or older, finding a 8.2% prevalence of homeopathy use. A Norwegian cross-sectional study evaluated 7,888 families, reporting that the homeopathy use prevalence amounted to 6% ²⁰20. Steinsbekk A. Families' visits to practitioners of complementary and alternative medicine in a total population (the HUNT studies). Scand J Public Health 2010; 38(5 Suppl):96-104.. Dossett et al. ¹⁹19. Dossett ML, Davis RB, Kaptchuk TJ, Yeh GY. Homeopathy use by US adults: results of a national survey. Am J Public Health 2016; 106:743-5. used the 2012 National Health Interview Survey (NHIS), finding a 2.1% prevalence of homeopathy use among adults in the United States. The 2002 and 2007 NHIS reported an annual homeopathy use prevalence among adults in the United States of 1.7% and 1.8%, respectively ²¹21. Barnes PM, Bloom B, Nahin RL. Complementary and alternative medicine use among adults and children: United States, 2007. Natl Health Stat Report 2008; (12):1-23.. Thomas & Coleman ²²22. Thomas K, Coleman P. Use of complementary or alternative medicine in a general population in Great Britain. Results from the National Omnibus Survey. J Public Health (Oxf) 2004; 26:152-7. interviewed a representative sample of adults in England, Scotland, and Wales, finding an annual prevalence of homeopathy use at 1.9%. A study which used the French national health insurance databases (SNIIRAM) to analyze prescriptions of reimbursed homeopathic drugs or preparations in the overall French population from July 2011 to and June 2012 found a higher prevalence (10.2%), which means that a total of 6,705,420 patients received at least one reimbursement for a homeopathic remedy during a 12-month period ²³23. Piolot M, Fagot JP, Rivière S, Fagot-Campagna A, Debeugny G, Couzigou P, et al. Homeopathy in France in 2011-2012 according to reimbursements in the French national health insurance database (SNIIRAM). Fam Pract 2015; 32:442-8..

Overall, two studies systematically reviewed data on homeopathy use prevalence in different countries. Cooper et al. ¹⁸18. Cooper KL, Harris PE, Relton C, Thomas KJ. Prevalence of visits to five types of complementary and alternative medicine practitioners by the general population: a systematic review. Complement Ther Clin Pract 2013; 19:214-20. assessed 41 surveys across 12 countries of the 12-month prevalence of visits to complementary and alternative medicine practitioners for five therapies, including homeopathy. They found a 1.5% prevalence of visits to a homeopath among adults was 1.5%. Relton et al. ⁸8. Relton C, Cooper K, Viksveen P, Fibert P, Thomas K. Prevalence of homeopathy use by the general population worldwide: a systematic review. Homeopathy 2017; 106:69-78. summarized prevalence data for both treatments by a homeopath and all homeopathy use, including purchases of OTC homeopathic medicines from 11 countries (United States, United Kingdom, Australia, Israel, Canada, Switzerland, Norway, Germany, South Korea, Japan, and Singapore). They reported a 1.5% 12-month prevalence of homeopathic treatment among adults from 24 surveys (from 0.2% to 8.2%). Rates in the United States, United Kingdom, Australia, and Canada ranged from 0.2% to 2.9%, and remained stable over the years surveyed (1986 to 2012). The 12-month prevalence of all use of homeopathy among adults (purchase of OTC homeopathic medicines and treatment by a homeopath) reported in 10 surveys was 3.9% (from 0.7% to 9.8%). Rates in the Unitd States and Australia ranged from 1.7% to 4.4% and remained stable over the surveyed years. Boing et al. ⁹9. Boing AC, Santiago PHR, Tesser CD, Furlan IL, Bertoldi AD, Boing AF. Prevalence and associated factors with integrative and complementary practices use in Brazil. Complement Ther Clin Pract 2019; 37:1-5. reported a 0.6% prevalence of homeopathy use among Brazilian adults, slightly lower than our findings. Possible explanations for the lower rate of homeopathy users in Brazil are the perception that homeopathy is unable to treat patients with more complicated diseases, the lack of high-quality research assessing the effects of homeopathy, and the lack of information from health managers in the country ²⁴24. Salles SAC, Schraiber LB. Gestores do SUS: apoio e resistências à Homeopatia. Cad Saúde Pública 2009; 25:195-202.. A further reason may be the costs of homeopathic products. Even though the SUS provides public homeopathy appointments, it fails to cover the medication costs. Homeopathy products are expensive for a great portion of the population. This is in line with our findings, as less than 5% of the homeopathy users reported not having to pay for treatment.

The literature offers mixed evidence on the sociodemographic and health profile of people who seek TCIM treatments in general. Peltzer & Pengpid ¹²12. Peltzer K, Pengpid S. Prevalence and determinants of traditional, complementary and alternative medicine provider use among adults from 32 countries. Chin J Integr Med 2018; 24:584-90. used data from 32 countries to show that middle-aged women with lower educational attainment and socioeconomic status were associated with seeking TCIM treatments. In contrast, Guillaud et al. ²⁵25. Guillaud A, Darbois N, Allenet B, Pinsault N. Predictive factors of complementary and alternative medicine use in the general population in Europe: a systematic review. Complement Ther Med 2019; 42:347-54. systematically summarize data on the predictive factors for seeking TCIM treatments in Europe, finding that only being female and having a self-reported chronic disease are predictive factors of seeking TCIM treatments. They concluded that they were unable to draw any conclusions for all other investigated factors. Similarly, a review with 110 articles highlighted the importance of understanding specific types of TCIM use in specific populations, suggesting that there is not a single profile that characterizes those seeking TCIM treatments ¹¹11. Bishop FL, Lewith GT. Who uses CAM? A narrative review of demographic characteristics and health factors associated with CAM use. Evid Based Complement Alternat Med 2010; 7:11-28.. However, whether these results can be used to characterize a profile of the homeopathy user is still unclear.

Few studies tried to evaluate the relation of sociodemographic characteristics and health status with homeopathy use. Many assessed community-based non-clinical populations. Overall, estimates vary between countries, depending on the analyzed predictive factor. A study evaluated homeopathy users’ characteristics during the previous 12 months in 50,827 inhabitants from Central Norway, finding that female homeopathy users had higher education and more chronic complaints, whereas male ones were more likely to seek help for psychiatric complaints ²⁶26. Løhre A, Rise MB, Steinsbekk A. Characteristics of visitors to practitioners of homeopathy in a large adult Norwegian population (the HUNT 3 study). Homeopathy 2012; 101:175-81.. They failed to report an association between age, marital status, and perceived global health with visiting homeopathic treatment providers. Curiously, a previous study in the same geographic area found that people aged 60 or over were more likely to seek homeopathic treatment ²⁷27. Steinsbekk A, Nilsen TVL, Rise MB. Characteristics of visitors to homeopaths in a total adult population study in Norway (HUNT 2). Homeopathy 2008; 97:178-84.. In France, a nationwide observational survey compared 6,379 patients who visited general practitioners (GPs) who prescribed only conventional medicines (GP-CM), regularly prescribed homeopathy within a mixed practice (GP-Mx), or are certified homeopathic GPs (GP-Ho). They concluded that patients attending a GP-Ho were slightly more often women with higher education than those in the GP-CM group and had markedly healthier lifestyles. They found no great differences regarding comorbidities or quality of life. Nevertheless, patients seeking care with a homeopath GP greatly differ in their healthier lifestyles, and positive attitude toward complementary medicine and natural treatments ²⁸28. Lert F, Grimaldi-Bensouda L, Rouillon F, Massol J, Guillemot D, Avouac B, et al. Characteristics of patients consulting their regular primary care physician according to their prescribing preferences for homeopathy and complementary medicine. Homeopathy 2014; 103:51-7.. Another French study assessed the prevalence and characteristics of homeopathy users, in Caucasian 3,249 women and 2,937 men aged 35-74 years, randomly sampled from the complete list of Lausanne inhabitants ²⁹29. Marques-Vidal P, Pécoud A, Hayoz D, Paccaud F, Mooser V, Waeber G, et al. Prevalence and characteristics of homeopathy users in a representative sample of the Lausanne population: CoLaus study. Pharmacoepidemiol Drug Saf 2008; 17:209-11.. Homeopathy use was positively associated with the female gender and higher educational attainment, but was unrelated to most common chronic diseases ²⁹29. Marques-Vidal P, Pécoud A, Hayoz D, Paccaud F, Mooser V, Waeber G, et al. Prevalence and characteristics of homeopathy users in a representative sample of the Lausanne population: CoLaus study. Pharmacoepidemiol Drug Saf 2008; 17:209-11.. In Brazil, a probabilistic cross-sectional study with a cluster sampling of 3,080 participants reported, that the female gender and higher schooling and income were associated with homeopathy use ³⁰30. Rodrigues-Neto JF, Figueiredo MFS, Faria AA. Prevalence of the use of homeopathy by the population of Montes Claros, Minas Gerais, Brazil. São Paulo Med J 2009; 127:329-34.. Another Brazilian study with elderlies older adults (≥ 60 years of age) (N = 23,815) found that homeopathy used was associated with the female gender and with specific chronic diseases ³¹31. Marques PP, Francisco PMSB, Bacurau AGM, Rodrigues PS, Malta DC, Barros NF. Uso de práticas integrativas e complementares por idosos: Pesquisa Nacional de Saúde 2013. Saúde Debate 2020; 44:845-56.. Until recently, Boccolini & Boccolini ¹⁰10. Boccolini PMM, Boccolini CS. Prevalence of complementary and alternative medicine (CAM) use in Brazil. BMC Complement Med Ther 2020; 20:51. conducted the largest population-based study in Brazil, using data from the PNS 2013. According to these authors, the wealthiest in the country were more likely to seek homeopathic and acupuncture treatments, whereas the poorest part of the population were more likely to use medicinal plants and herbal medicines. The sociodemographic profile of homeopathy users seen in these Brazilian studies agreed with our results.

The relation between self-reported health status and depression with TCIM, in general, and with homeopathy use, in particular, is also controversial. According to Peltzer & Pengpid ¹²12. Peltzer K, Pengpid S. Prevalence and determinants of traditional, complementary and alternative medicine provider use among adults from 32 countries. Chin J Integr Med 2018; 24:584-90., poor health status, unhappiness, and depression were factors associated with seeking TCIM treatment. This higher use of TCIM practices among individuals with mental conditions and poorer health status may be due to an increased health-seeking behavior that which goes beyond conventional medicine ³²32. Falci L, Shi Z, Greenlee H. Multiple chronic conditions and use of complementary and alternative medicine among US adults: results from the 2012 National Health Interview Survey. Prev Chronic Dis 2016; 13:E61.. However, an analysis to evaluate whether a self-perceived health status and psychological health are related to TCIM use yielded inconsistent results. The authors claimed that the cross-sectional designs employed in many studies are inappropriate to assess whether poor diagnosed or self-perceived health triggers TCIM use ¹¹11. Bishop FL, Lewith GT. Who uses CAM? A narrative review of demographic characteristics and health factors associated with CAM use. Evid Based Complement Alternat Med 2010; 7:11-28..

Aiming to explain the relation between mental health conditions and homeopathy, Grolleau et al. ¹⁴14. Grolleau A, Bégaud B, Verdoux H. Characteristics associated with use of homeopathic drugs for psychiatric symptoms in the general population. Eur Psychiatry 2013; 28:110-6. employed an interesting approach. They evaluated the association between patient characteristics with their lifetime use of homeopathic treatment for psychiatric symptoms in a sample of 36,785 persons participating in the Mental Health Survey in the general French population. They reported that 1.3% of participants were being received homeopathic treatment for psychiatric symptoms, and younger women and higher educational attainment were associated with homeopathy use. Compared to persons with no lifetime use of psychotropic drugs, those using homeopathy were more likely to show a diagnosis of mood or anxiety disorders. This general population study suggested that homeopathic treatment for psychiatric symptoms seems to be especialy used to reduce anxiety symptoms. A nationwide evaluation of complementary medicine in Switzerland also found that homeopathy patients are more likely to be younger women with higher educational attainment who more often suffer from mental disorders than patients in conventional care ³³33. Marian F, Joost K, Saini KD, von Ammon K, Thurneysen A, Busato A. Patient satisfaction and side effects in primary care: an observational study comparing homeopathy and conventional medicine. BMC Complement Altern Med 2008; 8:52.. In this study, poorer self-perceived health status and depression, which are closely related, were associated with homeopathy use even after controlling for all covariates. We can offer some explanations for these findings. Davidson et al. ³⁴34. Davidson JRT, Crawford C, Ives JA, Jonas WB. Homeopathic treatments in psychiatry: a systematic review of randomized placebo-controlled studies. J Clin Psychiatry 2011; 72:795-805. and Kessler et al. ³⁵35. Kessler RC, Soukup J, Davis RB, Foster DF, Wilkey SA, Van Rompay MI, et al. The use of complementary and alternative therapies to treat anxiety and depression in the United States. Am J Psychiatry 2001; 158:289-94. analyzed data from a nationally representative survey of 2,055 respondents from the United States, finding that there is a more widespread use of TCIM among people with self-defined anxiety attacks and severe depression. Moreover, they are used as an complementary treatment rather than a substitute for conventional psychotropic drugs or psychotherapy ³⁵35. Kessler RC, Soukup J, Davis RB, Foster DF, Wilkey SA, Van Rompay MI, et al. The use of complementary and alternative therapies to treat anxiety and depression in the United States. Am J Psychiatry 2001; 158:289-94.. Studies confirmed this practice among the general population ³⁶36. Makich L, Hussain R, Humphries JH. Management of depression by homeopathic practitioners in Sydney, Australia. Complement Ther Med 2007; 15:199-206.^,3737. Trichard M, Lamure E, Chaufferin G. Study of the practice of homeopathic general practitioners in France. Homeopathy 2003; 92:135-9.. Other reasons are dissatisfaction with conventional care ³⁸38. Sirois FM, Gick ML. An investigation of the health beliefs and motivations of complementary medicine clients. Soc Sci Med 2002; 55:1025-37. or patients’ fear of the side effects of psychotropic drugs ¹⁴14. Grolleau A, Bégaud B, Verdoux H. Characteristics associated with use of homeopathic drugs for psychiatric symptoms in the general population. Eur Psychiatry 2013; 28:110-6.. A previous study reported that persons with high educational attainment were less likely to use psychotropic treatments ³⁹39. Grolleau A, Cougnard A, Bégaud B, Verdoux H. Congruence between diagnosis of recurrent major depressive disorder and psychotropic treatment in the general population. Acta Psychiatr Scand 2008; 117:20-7.. Finally, according to a Swiss longitudinal community study, TCIM users may also be, in general, more likely to be vulnerable to anxiety and depression ⁴⁰40. Rössler W, Lauber C, Angst J, Haker H, Gamma A, Eich D, et al. The use of complementary and alternative medicine in the general population: results from a longitudinal community study. Psychol Med 2007; 37:73-84.. The use of homeopathy as a main or complementary treatment for depression is intriguing, as the literature has scarce evidence on homeopathy efficacy in these cases. Randomized and controlled double-blind trials comparing homeopathy efficacy versus placebo to treatment of depression showed no difference between the placebo and homeopathy groups ³⁴34. Davidson JRT, Crawford C, Ives JA, Jonas WB. Homeopathic treatments in psychiatry: a systematic review of randomized placebo-controlled studies. J Clin Psychiatry 2011; 72:795-805.. Nevertheless, a recent systematic review of randomized controlled trials for psychiatric disorders found that homeopathy more effectively treated major depression than fluoxetine. Note that this finding was based on the analysis of two trials with many methodological problems ⁴¹41. Rotella F, Cassioli E, Falone A, Ricca V, Mannucci E. Homeopathic remedies in psychiatric disorders: a meta-analysis of randomized controlled trials. J Clin Psychopharmacol 2020; 40:269-75..

A strength of our study is its use of data from a large national survey with complex sampling. PNS sampling included Brazilians from all regions of the country and from several socioeconomic strata, which enables us to generalize our results. Finally, PNS reported an overall 12-month prevalence of any TCIM practice, including homeopathy, making it potentially more representative of the general population than data from surveys of only one type of therapy.

However, this study also has some limitations. First, PNS 2019 is a cross-sectional study. Therefore, it stops us from inferring temporal causality. Second, we evaluated our main outcome regarding on homeopathy use via single direct question that which respondents could interpret differently. The prevalence of homeopathy use could be biased due to this lack of a clear definition of what is a homeopathic treatment. On one hand, participants may consider homeopathic treatments as different types of complementary and integrative formulas, such as medicinal plants and herbal medicines. On the other hand, homeopathic medicines can be consumed without a medical prescription, and consumers may fail not to consider the OTC use of homeopathy as a “medical treatment”. Unfortunately, we lack medical data to confirm the use of homeopathy, as well of other types of complementary and integrative practices, which is a common problem in large population-based studies in the field. Finally, misclassification and recall bias are potential limitations of our study. In total, two factors contribute to these biases: the use of self-reports to assess our main outcome and explanatory variables, and the length of time the participants had to recall the homeopathic treatment (last 12 months). Nevertheless, the assessment of whether or not there was use of homeopathy in the last 12 months in the participants’ self-report is commonly employed in this type of survey.

Conclusions

In recent years, Brazil saw an expansion of TCIM practices being offered by SUS. Nevertheless, according to data from PNS 2013 and 2019, the prevalence of homeopathy use varied only from 0.6% to 0.99%, and the most people treated with homeopathy paid for their treatment. We also found a clear association between homeopathy use and certain characteristics, such as higher socioeconomic and educational status, and patients who are more often women suffering from depression. The literature requires further research to evaluate the direction of these associations. Additionally, studies about the effectiveness and cost-effectiveness of homeopathy among people suffering from depression and other medical conditions are needed.

References

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