Prevalence of Use of Traditional, Complementary and Alternative Medicine by the General Population: A Systematic Review of National Studies Published from 2010 to 2019

Traditional, complementary and alternative medicine (TCAM) refers to a broad range of health practices and products typically not part of the 'conventional medicine' system, and its use is substantial among the general population. TCAM products and therapies may be used in addition to, or instead of, conventional medicine approaches, and some have been associated with adverse reactions or other harms. The aims of this systematic review were to identify and examine recently published national studies globally on the prevalence of TCAM use in the general population, to review the research methods used in these studies and to propose best practices for future studies exploring prevalence of use of TCAM. MEDLINE, Embase, CINAHL, PsycINFO and AMED were searched to identify relevant studies published since 2010. Articles/reports describing the prevalence of TCAM use in a national study among the general population were included. The quality of included studies was assessed using a risk of bias tool developed by Hoy et al. Relevant data were extracted and summarised. Forty studies from 14 countries, comprising 21 national surveys and one cross-national survey, were included. Studies explored the use of TCAM products (e.g. herbal medicines), TCAM practitioners/therapies, or both. Included studies used different TCAM definitions, prevalence time frames and data collection tools, methods and analyses, thereby limiting comparability across studies. The reported prevalence of use of TCAM (products and/or practitioners/therapies) over the previous 12 months was 24–71.3%. The reported prevalence of use of TCAM (products and/or practitioners/therapies) is high, but may underestimate use. Published prevalence data varied considerably, at least in part because studies utilise different data collection tools, methods and operational definitions, limiting cross-study comparisons and study reproducibility. For best practice, comprehensive, detailed data on TCAM exposures are needed, and studies should report an operational definition (including the context of TCAM use, products/practices/therapies included and excluded), publish survey questions and describe the data-coding criteria and analysis approach used. Traditional, complementary and alternative medicine (TCAM) includes products (e.g. herbal medicines, dietary supplements) and therapies/practices (e.g. chiropractic, acupuncture), and is a popular healthcare choice for many people. This study systematically reviewed national surveys of TCAM use around the world. We identified studies carried out in 14 different countries and one continent (Europe) on the extent of use of TCAM in the general population. TCAM use was found to be substantial, ranging from 24 to 71.3% in different countries. National surveys use different methods and different survey questionnaires. Some studies did not publish the survey questionnaire that they used and/or did not describe the types of TCAM included in the study. This means that it is not possible to compare the results between countries or to do further data analysis. For example, the survey questions from different countries asked people if they had ‘used’ or ‘seen a practitioner’ for a specific therapy, such as homeopathy. These questions look similar, but could elicit different answers from people. This means that the answers to these questions cannot be pooled together or compared directly. Also, some studies collected information on use of a category of TCAM products, such as herbal medicines, but other studies collected information on use of specific herbal medicines, such as St John’s wort. New surveys of the extent of use of TCAM should provide full information on the types of TCAM products, practices and therapies included in the study and consider collecting comprehensive information on use of specific TCAM products, practices and therapies.