Introduction

The rapid increase in the population and related medical care of older people are major concerns that affect all countries [1–3]. It is estimated that the population of people older than 65 years is projected to rise from 771 million in 2022 to 1.6 billion in 2050 worldwide [4]. A high annual medical expenditure of older people can be expected because the per capita lifetime expenditure of health care is $316,600 and nearly half during the senior years [5]. Undoubtedly, biochemical medicine, also called conventional medicine or Western medicine, is the most commonly used type of medical care. However, the increasing use of complementary and alternative medicine (CAM) has attracted attention, and medical pluralism is a trend worldwide [6].

CAM is the term for medical products and practices that are not part of standard medical care that became popular worldwide in the past 20 years [7]. It has been reported that the one-year prevalence of CAM use among American, Asian-American, and European older people is 27%-62%, 48–76%, and 33.5%, respectively [8–11]. Traditional Chinese medicine (TCM) is a complete CAM healing system and is widely used in Taiwan, China, Korea, Japan, and other Asian countries [12–17]. In the general population in Taiwan, the prevalence rates of TCM use for one month, one year, and six years were reported as 10.4%, 28.4%, and 62.5%, respectively [14–16]. In a cross-sectional study in Japan, 71.5% of interviewees requested CAM practice at hospitals, and most of them accepted TCM [17]. The therapeutic effect of TCM has been confirmed, and it is commonly used in patients with cardiovascular diseases, kidney disease, stroke, cancer, and other diseases [18, 19]. Previous studies have also investigated the beneficial effects of TCM on patients with COVID-19. Given the comprehensive nature of TCM, it is a well-suited choice for utilization among elderly individuals.

In Shanghai, the lifetime prevalence of the use of TCM among people aged 50 years and older was estimated to be as high as 50% [12]. Among Korean people who used traditional Korean medicine (similar to TCM) in the past year, 41.8% of them were older people aged over 65 years [13]. In Taiwan, the 6-year prevalence (1996–2001) of TCM use among older people aged over 61 years was as high as 61% [20]. Another report also showed that 48% of elderly patients aged 65 years and older had used TCM at least once from 2005–2009 in Taiwan [21]. However, no studies have focused on TCM use among older people after 2010.

In Taiwan’s health care system, there are two types of medical doctor licenses: one for Western medicine physicians and another for TCM physicians. Both medical care systems are covered by National Health Insurance, and people do not need to pay much money when seeking medical care by Western medicine (WM) or TCM physicians in Taiwan. Although the utilization rate of TCM among older people has been studied in previous reports, information regarding recent full-spectrum utilization of TCM is limited. Using population-based data from an interview survey, the purpose of this study was to evaluate the prevalence, frequency, and associated factors of TCM use among people aged 65 years and older in Taiwan.

Methods

Results

Fig 1 shows that the one-month prevalence of TCM use increased from 5.5% in 2001 to 9.1% in 2017 among older people in Taiwan. Overall, there were 13945 older people in this study, and 7.3% of them had used TCM within the previous month (Table 1). The chi-square test showed that women (8.1%) had a higher use of TCM than men (6.4%, p<0.0001). Higher use of TCM was found among people aged 65–69 years (compared with ≥80 years, p<0.0001) and those who had heart disease (compared with those who did not, p<0.0001), liver disease (compared with those who did not, p = 0.0021), and previous emergency care (compared with those who did not, p = 0.0081). People who smoked (p<0.0001), utilized folk medicine (p<0.0001), and purchase of non-prescribed CHM (p<0.0001) had a higher TCM use than those without these factors.

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Fig 1. The one-month prevalence of use of traditional Chinese medicine among older people in Taiwan, 2001–2017.

https://doi.org/10.1371/journal.pone.0302658.g001

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Table 1. The characteristics of older people aged more than 65 years with and without use of traditional Chinese medicine in 2001–2017.

https://doi.org/10.1371/journal.pone.0302658.t001

As shown in Table 2, age ≥80 years was associated with reduced use of TCM (OR 0.48, 95% CI 0.31–0.72). We also found that people with a history of heart disease (OR 1.62, 95% CI 1.24–2.12), those who used folk medicine (OR 3.16, 95% CI 2.00–4.99), and those who purchased non-prescribed CHM (OR 2.08, 95% CI 1.48–2.91) were more likely to use TCM than those with no heart disease, those who did not use folk medicine, and those who had not purchased non-prescribed CHM. Previous hospitalization was associated with reduced use of TCM (OR 0.59, 95% CI 0.41–0.85).

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Table 2. Crude and adjusted odds ratios and confidence intervals of factors associated with use of traditional Chinese medicine.

https://doi.org/10.1371/journal.pone.0302658.t002

Table 3 shows the medical visits for TCM among people with various characteristics. Compared with older people without hyperlipidemia, patients with hyperlipidemia had a higher average frequency of TCM use (3.0±3.6 vs. 2.5±2.9 visits, p = 0.0239). Older people who consumed alcohol had fewer visits for TCM use than older people who did not consume alcohol (1.3±0.5 vs. 2.6±3.1 visits, p = 0.0066).

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Table 3. Visits frequency of traditional Chinese medicine among older people aged more than 65 years in 2001–2017 (N = 1019).

https://doi.org/10.1371/journal.pone.0302658.t003

Discussion

Using data from the National Health Interview Survey in Taiwan, we found a high prevalence rate of 7.3% for the utilization of TCM within the past month in the population older than 65 years in 2001–2017. Age, cardiovascular disease, kidney disease, the use of folk medicine and the purchase of non-prescribed CHM were associated with the long-term utilization of TCM.

Among Chinese-American older adults in Chicago, 76% reported any use of TCM within the past year [10]. The lifetime prevalence of the use of TCM among people aged 50 years and older in Shanghai was 50% [12]. Comparing the use of TCM in the Chinese population in other countries [10, 12], the corresponding rate of TCM use in this study was relatively low (7.3% within the past month). A possible explanation is that the contents of TCM use in other reports in America or China included treatment procedures not performed by physicians. Certainly, the estimated period of utilization varied in reports and is also a reason for the discrepancy in TCM use.

The utilization of TCM among older people in Taiwan has been reported in previous studies [6, 14, 20]. In 2001, the one-year prevalence of TCM use among people aged 65 and over in Taiwan was 25.9% [6]. A national health survey in Taiwan showed that the prevalence of TCM use among older people aged over 70 years in 2002 was 7.7% [14]. From 2005–2009, 48% (the five-year prevalence) of older people had used TCM at least once in Taiwan [20]. The use of TCM in our study was higher than that in a previous report because we measured utilization among elderly individuals on a monthly basis instead of annually, and it is important to note the differences in utilization rates measured over different time periods. In Taiwan, both the ratio of TCM users and mean TCM visits increased gradually from 2000 to 2005 and even further to 2010 among elderly people [24]. However, we could not exclude the possibility of recall bias among the older people in this study.

Our study found that older people aged 75–79 or ≥80 years had lower ORs of TCM utilization than those aged 65–69 years. The findings of this study were consistent with those of previous studies in Taiwan that indicated that younger people possessed much more knowledge, adequate attitudes, and active practices regarding TCM and exhibited a higher frequency of TCM utilization than older people [14, 20, 25]. Moreover, living in health care institutions, limited mobility, and regular visits to Western medicine practitioners (such as for renal dialysis) are possible reasons why older people aged 75 and above had a reduced use of TCM in this study.

A study based on a systematic review suggested the beneficial effects of TCM on cardiovascular disease, hypertension, and the outcomes of coronary heart disease and heart failure [26]. Dan Shen is a common herb in CHM that is widely used in Asia because of its benefits for cardiovascular diseases [27]. It contains hydrophilic phenolic acids and lipophilic tanshinones, which are believed to contribute to its therapeutic efficacy. Studies have shown that Dan Shen reduces the risk of coronary heart disease in patients and protects the vascular endothelium [28, 29]. Moreover, previous studies also identified Dan Shen as a commonly prescribed TCM prescription for elderly individuals in Taiwan [21]. Therefore, it is reasonable that older people with heart disease were more likely to use TCM than those with no heart disease in this study.

Taiwan has the highest incidence of end-stage renal disease worldwide [30]. The risk of developing chronic kidney disease shows an exponential increase after 60–64 years [31]. Due to the limited treatment options for chronic kidney disease in clinical conventional medicine settings, some patients turn to secondary medical advice or alternative therapies, including TCM [32]. TCM has shown potential beneficial effects on improving kidney function, hemoglobin levels, and serum albumin levels and reducing proteinuria [33–36]. However, we found that older people with kidney disease had a higher likelihood of using TCM but had a lower frequency of TCM use in this study. This implies that older people with chronic kidney disease used TCM once. We considered that patients with end-stage renal disease receiving dialysis two or three times weekly might have had less opportunity to use TCM.

In this study, we found that older people who used folk medicine had a higher likelihood of TCM use, which is consistent with the results of previous studies [22]. In Taiwan, TCM includes CHM, acupuncture, moxibustion, bone reduction, traditional trauma treatment, traditional dislocation treatment, traditional fracture treatment, tui-na, ba-guan, and other therapies. Folk medicine also includes acupressure, Chinese massage, cupping and skin scraping, and CHM without a physician’s prescription. Unsurprisingly, the use of folk medicine was associated with the utilization of TCM in this study because several items and contents are similar between folk medicine and TCM. We also considered that older people may not recognize the safety, legality, or efficacy of TCM or folk medicine. In fact, TCM practitioners in Taiwan are registered TCM physicians who are certified, licensed, and practice in a hospital or clinic setting. TCM in Taiwan is recognized as a health service and treatment modality, and TCM physicians can legally advertise the medical benefits of TCM and claim reimbursement from National Health Insurance.

Purchasing CHM without a physician’s prescription is common in Taiwan [23, 37]. In this study, we found that purchasing non-prescribed CHM was associated with the use of TCM among older people. A previous study found that older people purchased non-prescribed CHM more than other age groups [23]. Another study also suggested that TCM outpatient visits with the purchase of non-prescribed TCM products (not covered by National Health Insurance) were more frequent among individuals over the age of 65 compared to other age groups [38]. With the widespread presence of Chinese herbal pharmacies and the possibility of purchasing most types of non-prescribed CHM, there is a noticeable trend indicating a heightened acceptance among people toward the use and purchase of non-prescribed CHM in Taiwan. Physicians need to understand the conditions regarding the purchase of non-prescribed CHM among their patients.

The previous two studies had found that use of folk therapy was significantly associated with the purchase of non-prescribed CHM [22, 23, 37]. We could hypothesize that people who choose to use folk therapy or to purchase non-prescribed CHM were the active population with seeking second treatment opinion. Many patients choose to use folk therapy or purchase of non-prescribed CHM based on a recommendation from someone who has used the therapy and has been satisfied with the results [22, 23, 37]. However, the health authority and physicians discouraged patients to seek folk therapy or to purchase non-prescribed CHM. It should be cautioned that non-prescribed CHM and folk therapy per se and the interactions within TCM, non-prescribed CHM, and folk therapy were risky because the uncertain content and unlicensed executors of non-prescribed CHM and folk therapy.

There were some limitations that should be noted when interpreting the results of this study. First, there was a possibility of recall bias among the elderly participants, as their ability to accurately recall past health care experiences may have been influenced by various factors. Because the information of sociodemographic factors, medical conditions and utilization were defined as within recent 12 months before the face-to-face questionnaire interview, the recall bias could not be excluded in this study, Second, the cross-sectional study design used in this research did not allow us to establish causal relationships between the use of TCM and related factors. Therefore, caution should be exercised when interpreting the findings of this study in terms of causality. Third, it is important to acknowledge that the timeframe of the analyses spanned a wide range. The potential effects of temporal and policy influences on the utilization of TCM could not be controlled for in this study. Fourth, other factors have been reported as factors associated with TCM use that could not be considered in this study, such as socioeconomic status, physical activity or exercise, and family support. Although we used multiple logistic regression and controlled for many potential confounding factors, residual confounding may persist in this study.

In conclusion, the use of TCM increased in 2001–2017 among older population aged 65 and older in Taiwan and the one-month prevalence of TCM use was associated with age, cardiovascular disease, kidney diseases, use of folk medicine, and the purchase of non-prescribed CHM. This study highlights the need for health care among older people who seek TCM and could be considered a reference for health regulatory agencies in future policies.

Acknowledgments

This study is based on data obtained from Health and Welfare Information Science Center, Ministry of Health and Welfare, Taiwan. The interpretation and conclusions in this paper do not represent Ministry of Health and Welfare, Taiwan. The authors deeply thank Prof. Chun-Chuan Shih who contributed very much to this work.