Stroke is a non-communicable disease and a focal neurological disturbance of vascular origin that lasts more than 24 h(Khaku and Tadi, 2020). According to the World Stroke Organization, 13.7 million new stroke cases are diagnosed each year worldwide (Lindsay et al., 2019) and approximately 80 million people in the world have had a stroke. Overall, Oceania, Southeast Asia, North Africa, the Middle East, and East Asia had the highest age-standardized stroke prevalence rates in 2019. The countries with the highest prevalence rates of ischemic stroke were found in North Africa and the Middle East, southern Sub-Saharan Africa, high-income North America, and Southeast Asia (Virani et al., 2021). Stroke has been intended to become the second largest cause of mortality by 2040 (MOH, 2019). On average, 92 admissions and 32 deaths occur each day across Malaysia’s healthcare facilities (MOH, 2019). The prevalence of stroke in Malaysia was estimated to be 0.3% in 2006 during the third National Health and Morbidity Survey (NHMS). Stroke is a chronic condition characterised by acute events (O’Neill et al., 2008). Thus, long-term therapy is indicated for stroke patients, especially antiplatelet, antihypertensive, and lipid-lowering agents for ischemic stroke and anticoagulants for embolic stroke (MOH, 2012; Linden, 2020). Therefore, adherence is an important factor in determining the clinical outcomes of stroke patients.

Complementary alternative medicine (CAM) is comprised of diverse structures, methods, and products that are not commonly considered part of traditional medicine (Barnes et al., 2008). In Asian and African countries, the type of CAM used to treat stroke may vary due to geographical and cultural differences (Jeong et al., 2016). In the last decade, there has been a rapid rise in interest in CAM among stroke patients. CAMs are commonly categorized into five groups, according to the National Center for Complementary and Alternative Medicine (NCCAM) (2005): biological, spiritual/mind-body, alternative, physical (body-based), and energy therapies (Wieland et al., 2011). CAM for stroke includes acupuncture, herbal remedies, Ayurveda, Chinese medicine, homeopathy, mind-body techniques, and physio (Shin et al., 2008). Studies have suggested that CAM is used worldwide (Aydin et al., 2008; Fox et al., 2010; Shaikh et al., 2009). Herbs, vitamins, herbal additives, enzymes, and minerals are biochemical processes, also known as natural goods, which are biological methods, while wellbeing activities include acupuncture, aromatherapy, cupping, meditation, praying (use of holy water, amulets, or talismans), and Zumba. Traditional medicines that differ from region to region are used in alternative medicine, such as traditional Chinese, Malay, Indian (Ayurvedic/Siddha/Unani) medicines, and homeopathic remedies (Rhodes et al., 2008; Wieland et al., 2011). Due to variations in cultural values and healthcare environments, the CAM use can vary. A survey indicated that 71.2% of respondents use CAM, wherein the use of herbal products was the most frequent. Recommendations from relatives and friends are the key justifications for using CAM (Jasamai et al., 2017).

Medication adherence is defined as the degree to which patients follow their doctor’s instructions and their persistence in fulfilling the span of time from start to discontinuation of therapy. (Shams and Barakat, 2010), (Vrijens et al., 2012) Meanwhile, adherence can also be defined as patients simply not taking their medications. Medication adherence measures are generally categorized as arbitrary and quantitative measurements by the WHO (Sabaté and Sabaté, 2003). Subjective assessments include those that require the appraisal of their medication-taking actions by the patient (Velligan et al., 2007). The most popular instruments used to test opioid adherence include self-reported questionnaires, for example, MMAS, as well as healthcare provider interviews. Quantitative tests include pill counts and secondary review of records, such as MPR, computer tracking, and biochemical measures (Vermeire et al., 2001).

The four primary factors related to medication non-adherence are patients (e.g., socioeconomic characteristics, and perceptions and beliefs), illness-related factors (e.g., severity of illness and frequency of symptoms), medication (e.g., number of daily doses, efficacy, and side effects), and physician-related ones (e.g., patient-physician relationship), (Greenhouse et al., 2000; Scott and Pope, 2002; Kleindienst and Greil, 2004). Medication non-adherence is a severe concern to patients with stroke, and the assumption that stroke has a moral or psychological origin can contribute to insufficient stroke treatment and stronger Dependency on CAM may lead to non-adherence to medication, however, there is a lack of information regarding the influence of CAM on the adherence of patients with stroke. The objectives of the present study were to evaluate patterns and types of CAM use, prevalence of medication adherence and to determine the effect of CAM on medication adherence in patients with stroke.

A total of 1,330 titles were recovered, and 93 duplicates were removed. The remaining papers were screened for inclusion and exclusion criteria. A total of 22 studies were included in the final analysis. The flow of research is shown in Figure 1.

Of the 31 studies, 12 focused on CAM usage among patients with stroke, (Lee et al., 2004; Shin et al., 2008; Shaikh et al., 2009; Chang et al., 2011; Liao et al., 2012; Pandian et al., 2012; Ali et al., 2015; Kadir et al., 2015; Chang et al., 2016; Teo et al., 2016; Weng et al., 2016; Yeh et al., 2017), 15 reported medication adherence, (De Schryver et al., 2005; Osterberg and Blaschke, 2005; Arif et al., 2007; Khan et al., 2010; Bushnell et al., 2011; Chambers et al., 2011; Kronish et al., 2013; Sjölander et al., 2013; Jiang et al., 2017; Kim et al., 2017; Wei et al., 2017; Cheiloudaki and Alexopoulos, 2019; Rohde et al., 2019; Han et al., 2020; Saade et al., 2021), and only 4 investigated CAM usage and patients’ adherence to stroke medications (Johnson et al., 2012; Karuniawati et al., 2017; Alhawsawi et al., 2020; Kim et al., 2020). The study design and country settings are summarized in Table 2, Table 3, Table 4 to Table 5.

In this study, the usage trends and effects of CAM on adherence to stroke treatment in stroke patients was reviewed. A total of 31 studies were included, within which the poor response rate in the surveys was a specific concern. Further issues with CAM surveys have been attributed to the fact that there is no widely agreed classification of CAM. Multiple approaches have been used to measure adherence in different studies. For many factors, self-reported questionnaires may overestimate adherence: first, they can depend on patients’ own understanding or recollection of what guidance has been provided; second, patients may appear to record higher levels of adherence in order to please healthcare professionals or prevent personal embarrassment (Tiv et al., 2012). Over time, the popularity of CAM treatments for stroke in developed nations has grown, at times in accordance with changes in the healthcare environment, the quality of schooling, and evolving societal values.

The most prevalent types of CAM usage by stroke patients reported in the studies reviewed were the use of herbal products, traditional Chinese medicine, massage, vitamins, and acupuncture. Meanwhile, the use of CAM has been studied among different sample populations including breast cancer, asthma, bone cancer, chronic diseases, and epilepsy, and the prevalence of CAM use was found to be 70.7, 61.1, 68, 63.9, and 26.7% respectively.^26-30 A wide variation in the prevalence of CAM use was observed in this review, between 12 and 67%. The meta-analysis, which was carried out on the prevalence of the CAM use data, showed high statistical variation in CAM usage among stroke patients across different studies. The subgroup analysis across countries’ income levels showed that upper middle-income countries, such as Malaysia, had the highest prevalence of CAM usage. This may be due to the multicultural and multiracial diversity of Malaysian citizens, which allows them to try different types of CAM that are available in Malaysia. (Jasamai et al., 2017).

Moreover, the prevalence of stroke medication non-adherence was reported in 6 of the studies, ranging between 5.7 and 30.2%. Similarly, meta-analysis showed a high statistical heterogeneity among the studies. Subgroup analysis across income levels found that high-income countries had the lowest average of non-adherence among stroke patients. This may be due to a higher level of disease awareness among stroke patients and better healthcare systems across high-income countries compared to upper-middle-income countries and lower-middle-income countries. Furthermore, the assessment methods used in these studies were mainly subjective (patient-reported questionnaires) and tended to overestimate patient adherence. Patient compliance can be estimated more reliably using a mixed-method methodology (i.e., using subjective and quantitative evaluation tools).

Forgetfulness, specific beliefs about medications, lack of patient knowledge on medication, fear of side effects, complex medication regimens, and a poor doctor-patient relationship were the most frequently reported factors associated with non-adherence to stroke medication. Similar findings were reported in a study in which patients on poly therapy were more likely to forget to take their medication (Han et al., 2020).

Next, the most frequently reported reasons for non-adherence among stroke patients were lack of knowledge, complex medication regimens, and poor relationships between physicians and patients. These factors are likely to contribute to a shift toward the use of CAM among patients with stroke (Johnson et al., 2012; Kim et al., 2018). Studies have shown that many stroke patients tend to concurrently use both CAM and stroke medication. This may be attributed to appealing marketing tactics employed by herbal and vitamin firms, who make promises about the advantages of complementary and alternative medicine (CAM), attracting these patients- However, there is a lack of clinical evidence regarding their efficacy in preventing the worsening of stroke or their safety profiles.

Pharmacists could conduct counselling and educational programs to help patients improve medication adherence and change their false perceptions about the etiology of stroke. According to one report, pharmacists should play a more active role in ensuring proper clinical knowledge is disseminated to patients (Islahudin and Tan, 2013). These findings are consistent with those of a study in which the compliance rate was high among patients with good knowledge about their disease (Omar and San, 2014). Moreover, the use of various compliance aids, such as pill boxes, medication reminders, and combination therapy (where possible) to reduce the number of pills, can improve adherence (Vervloet et al., 2012). Subsequently, in order to enhance patients’ understanding of their medication, pharmacists could counsel patients, providing details of drug names, doses, routes of administration, frequency of dosing, and duration of treatment (Osterberg and Blaschke, 2005). This information is important because it would promote the correct self-administration of medication among patients. As a result, counselling patients could mitigate adverse effects associated with medication non-adherence, thereby ensuring successful therapy.

With regards to the limitations of this work, there seems to be limited evidence on stroke medication non-adherence as a result of CAM usage. Although many studies have reported the reasons for CAM usage among stroke patients, among the 20 studies included in this review, the association between stroke medication adherence and CAM use was only assessed in three studies (Johnson et al., 2012; Karuniawati et al., 2017; J.; Kim et al., 2018).

Further studies investigating the resultant effects of CAM use by stroke patients will be needed to determine whether the treatment under consideration has a positive or negative impact on patients’ health conditions and adherence to medication.

The prevalence of CAM usage among stroke patients has been reported to range between 12 and 62.3%. Meanwhile, the prevalence of medication non-adherence among stroke ranged from 10.5 to 31.4%. Medication non-adherence is thought to result from a limited understanding of clinical treatments, fear of side effects, poor patient-physician relationships, complex medication regimens, and the use of CAMs instead of stroke medication. Due to the lack of published studies, evaluating the impact of CAM usage on adherence to medication among stroke patients is warranted to gain further.