Polypharmacy—taking more medications than clinically necessary—usually refers to the use of five or more drugs (Kim et al., 2014; Masnoon et al., 2017). With population aging and the rising prevalence of multiple chronic conditions, polypharmacy has become a growing global concern, with about half of those aged 65 and older taking five or more medications (Wastesson et al., 2018). In South Korea, 86.4% of older adults take six or more medications, and 44.9% are in a state of excessive polypharmacy by taking 21 or more medications (Kim et al., 2014). Older adults with polypharmacy face a heightened risk of adverse events, including cognitive impairment, falls, and mortality (Gnjidic et al., 2012; Kojima et al., 2012b). Potentially inappropriate medications often contribute to this problem by negatively affecting cognitive function and elevating the likelihood of neurodegenerative diseases (Park et al., 2017a; Park et al., 2017b).

Stroke survivors are particularly vulnerable to polypharmacy. As stroke commonly co-occurs with hypertension, diabetes, dyslipidemia, and heart disease, many patients take multiple drugs to address both risk factors and symptoms (Kose et al., 2017). A Scottish study reported that patients with stroke were more than twice as likely to have multimorbidity than those without stroke, with 12.6% taking 11 or more medications, compared with only 1.5% of the general population (Gallacher et al., 2014). Indeed, patients with stroke on more than five or six medications face an elevated risk of adverse events and falls (Kojima et al., 2012a; Kojima et al., 2012b). Given the physical disabilities and reduced quality of life often associated with stroke, polypharmacy can further complicate recovery and create additional barriers to rehabilitation.

Korean Medicine (KM), a branch of Traditional East Asian Medicine (TEAM), has a long history alongside Chinese and Kampo medicine (Lee et al., 2014). In recent years, TEAM approaches have been investigated for their potential to reduce polypharmacy. One retrospective study of 159 patients reported a significant drop in the total number of medications used after treatment with TEAM in those who showed symptomatic improvement (Takano et al., 2018). Another case report documented a reduction from 13 to two medications alongside clinical improvement (Nogami et al., 2019). These findings suggest that by addressing the symptoms that originally led to multiple prescriptions, TEAM—including KM—may lessen the medication burden. However, prior investigations have focused mainly on drug count reduction rather than exploring the broader impact on falls and mortality.

We utilize data from the National Health Insurance Service (NHIS) to examine whether insurance-covered KM treatments, namely acupuncture, can influence polypharmacy-related outcomes in older patients with stroke. Specifically, we compare fall and mortality rates among those with and without polypharmacy and KM usage. By clarifying KM’s potential role in mitigating the risks associated with multiple medications, we aim to inform more integrative approaches to managing the complex care needs of older stroke survivors.

We investigated how KM usage—primarily acupuncture—affects falls and mortality among older stroke survivors with varying degrees of polypharmacy. Using the NHIS database, we analyzed 25,034 patients who experienced a stroke, categorized them into polypharmacy (≥5 medications) or hyper-polypharmacy (≥10 medications) groups, and examined two outcomes over 3 years: all-cause mortality and falls resulting in fractures. PS matching was used to minimize baseline differences between KM users and non-users, balancing factors such as demographics, comorbidities, and stroke severity. We then applied Cox proportional hazards models to assess how KM influenced our outcomes, performing sensitivity checks to confirm the robustness of the results.

In the polypharmacy group, KM use was associated with a heightened risk of falls (aHR 1.52) but a reduced risk of all-cause mortality (aHR 0.66) compared with non-use. This seemingly paradoxical pattern of higher fall incidence yet lower all-cause mortality among KM users can be reconciled by mechanisms well documented in stroke-rehabilitation research, even though functional status could not be measured directly in the NHIS data. Multiple studies including randomized controlled trials show that post-stroke acupuncture, combined with targeted physical training and herbal prescriptions, accelerate gains in motor strength, gait speed, and activities of daily living, and shorten the modified Rankin Scale recovery (Liu et al., 2009; Yan and Hui-Chan, 2009; Zhao et al., 2009; Hong et al., 2024; Hu et al., 2024). Improved mobility enlarges patients’ “activity envelope”; because most post-stroke falls occur during routine ambulation rather than high-risk tasks (Wang et al., 2025; Morone et al., 2014), increased activity envelope predictably yields into more opportunities to fall. At the same time, enhanced locomotion curtails secondary complications such as pneumonia, pressure ulcers, sarcopenia and facilitates cardiovascular conditioning, which together have been linked to better long-term survival (Lui and Nguyen, 2018), which inadvertently raises fall risk if patients do not receive adequate balance training (Morone et al., 2014; Wei et al., 2019).

In contrast, among those with hyper-polypharmacy, KM did not significantly change fall risk (aHR 0.99) but still lowered all-cause mortality (aHR 0.64). As patients with severe polypharmacy often have more advanced multimorbidity and frailty, KM’s positive impact on mobility might be less pronounced in that group, explaining the nonsignificant difference in falls. These findings were consistent across various models and sensitivity analyses, indicating a robust protective effect of KM on mortality regardless of medication burden. The absence of significant interaction effects between KM use and medication counts for both falls and mortality suggests that the benefits of KM, particularly in reducing mortality, are broadly applicable across medication complexity levels.

Although the primary KM intervention was acupuncture, another major therapy is herbal medicine. Owing to gaps in insurance coverage, herbal medicine use is not fully captured in the NHIS claims data. However, nationwide survey data indicate that a substantial portion of KM users also utilize herbal remedies: 94.3% use acupuncture, 28.5% use herbal extracts, and 26.7% use herbal decoctions (Development, 2024). This widespread use likely means most herbal medicine users were included in our KM cohort. By analyzing how an insured medical services provided within the scope of KM interacts with extensive Western polypharmacy, our study tackles a genuinely ethnopharmacological question: can a traditional, system-based medical paradigm mitigate drug-burden complications in real-world stroke care? Herbal medicine has been reported to alleviate neurologic deficits (Yang et al., 2016; Yu et al., 2015; Han et al., 2018) and improve independence (Goto et al., 2011). By enhancing motor function and mobility, herbal therapies could further increase the risk of falls—walking is the most common activity preceding falls in stroke survivors (Weerdesteyn et al., 2008)—but also contribute to better overall recovery. Although the NHIS database does not allow itemization of separate herbs and herbal decoctions, their silent presence implies the integrated KM practice provided to the treatment group actually seen in clinics in real-world settings.

Well-documented herbal effects that we could not model quantitatively nevertheless remain clinically relevant for post-stroke patients. The reduction in mortality may be attributed to KM’s ability to improve various factors that can worsen prognosis in the post-stroke recovery period in addition to functional recovery, such as acupuncture improving post-stroke dysphagia (Long and Wu, 2012; Cohen et al., 2016), herbal medicines inhibiting the progression of acute cerebral infarction (Jung et al., 2003), preventing aspiration pneumonia (Iwasaki et al., 2007), promoting negative conversion of resistant bacteria (Kohno et al., 2021), reducing early neurological deterioration (Tian et al., 2021), and preventing recurrence (Lee et al., 2023; Jung et al., 2018). Collectively these mechanisms—neuroprotection, infection control, and secondary prevention—could explain the lower all-cause mortality we observed among KM users. In patients with severe multimorbidity, however, KM’s impact on mobility could be blunted (Yao et al., 2020) owing to increased medications (Muth and Glasziou, 2015), potentially explaining why fall risk was unchanged in the hyper-polypharmacy group. Even though individual herbal prescriptions were unmeasurable, the aforementioned literature shows that they plausibly augment the neuromuscular and systemic benefits of acupuncture while also carrying their own risk-benefit trade-offs. Recognizing those unseen contributions strengthens the biological coherence of our findings and highlights why future linked-dataset or prospective studies that capture uninsured herbal dispensing are essential for a full pharmacological accounting of KM in stroke rehabilitation.

While the neuromotor benefits of acupuncture and other KM modalities are well documented, the higher fall rate observed in KM recipients is more plausibly driven by survivor bias than by treatment-related harm. Our competing-risk sensitivity analysis showed that deaths accounted for 16%–54% of all first events and that, assuming constant hazards, the probability of death preceding a first fracture was ≈52%. Because KM users experienced lower early mortality, they contributed more person-time at risk and therefore had more opportunity to incur a fall. When this prolonged exposure is combined with the greater mobility that KM appears to foster, the crude fall incidence is inevitably inflated without implying an intrinsic increase in fall propensity. Accordingly, the excess falls should be viewed not as an adverse effect of KM itself but as the by-product of improved survival and functional recovery. Future studies with patient-level event ordering and richer clinical detail are needed to apply formal competing-risk methods—such as Fine–Gray sub-distribution models—and to verify this interpretation.

In the matched cohort, KM users had a higher prevalence of chronic pain conditions such as low back pain and osteoarthritis, suggesting that individuals with persistent pain may be more inclined to seek KM owing to its perceived or actual effectiveness. Acupuncture can alleviate chronic pain and encourage greater activity (Vickers et al., 2018), potentially improving quality of life (Manyanga et al., 2014; Seca et al., 2019). The resulting improvement in pain control and quality of life may encourage increased activity, contributing to fall risk but also enhancing overall health. This increased activity, however, can raise fall risk if patients resume normal routines without proper balance training or physical conditioning (Skelton, 2023). Nonetheless, better pain management may also slow the progression of other chronic conditions, potentially contributing to improved survival (Nielsen et al., 2022). While these benefits do not inherently lower fall risk, they highlight acupuncture’s broader role in chronic disease management, which can enhance patients’ overall longevity despite an accompanying increase in activity-related hazards.

Our study offers a fresh perspective on managing polypharmacy in older stroke survivors. Established criteria (Beers (Panel, 2015), STOPP/START (O'Mahony et al., 2023)) aim to reduce inappropriate prescribing but have shown mixed results in preventing adverse events (Frankenthal et al., 2014; Cole et al., 2023). In South Korea, where prescribing practices differ from Western settings (Lee et al., 2022), KM could serve as an integrative approach, potentially mitigating some negative outcomes of polypharmacy without reducing medication counts directly. We could not confirm whether KM helps discontinue medications, as we focused only on whether participants were in a polypharmacy state. Nevertheless, our findings strongly suggest that KM use is associated with improved survival regardless of medication load.

This study has limitations. First, we did not assess whether the number of medications changed over time or whether fewer drugs, in conjunction with KM, led to improved outcomes. Second, while acupuncture (including electroacupuncture) formed the main exposure, other integrative therapies such as herbal medicine might also have contributed to the outcomes (Lee et al., 2024). Third, the findings are specific to older stroke survivors and may not translate to other populations. We also did not examine prognostic factors such as cognitive impairment or frailty, which could influence falls and mortality.

This study has several strengths and limitations that must be weighed when interpreting the findings. On the strength side, we applied rigorous propensity-score methods and a large, nationally representative cohort of older stroke survivors, enabling precise estimates for outcomes such as post-stroke mortality. Nevertheless, limitations remain. First, we could not assess the relationship between the changes of the number of medications and the outcomes, precluding evaluation of whether subsequent de-prescribing—or the synergy between fewer drugs and Korean Medicine (KM)—mediated the observed associations. Second, although acupuncture (including electroacupuncture) constituted the primary exposure, ancillary KM modalities such as herbal prescriptions and manual therapies were not covered by NHIS and therefore were incompletely recorded in the database. It is important to note that these modalities may have contributed to both fall risk and survival. Third, several prognostic factors unavailable in NHIS database—including neurological severity (e.g., NIHSS), rehabilitation dose, family support, cognitive impairment, and frailty—could confound the results; if KM users were functionally milder or enjoyed greater social resources, the mortality benefit could be over-estimated and the excess falls under-estimated, whereas preferential KM use by more disabled patients would bias effects toward the null. Fourth, we could not evaluate pharmacodynamic interactions involving high-risk combinations—e.g., anticoagulants taken concurrently with selective-serotonin reuptake inhibitors or benzodiazepines—even though these pairings are well known to increase bleeding, sedation, and fall propensity. Reliable identification of such interactions would require granular data on dose, formulation, and administration timing, none of which are available in the NHIS claims files; thus a clinically meaningful co-exposure definition could not be constructed for the present analysis. Finally, because the cohort comprised elderly stroke survivors, generalizability to younger patients or to non-stroke populations is uncertain. Prospective studies that track dynamic medication exposure and incorporate detailed functional, cognitive, and social metrics are warranted to validate and extend these findings.

Among older stroke survivors, initiation of Korean Medicine (KM) within the first post-stroke year was linked to a higher incidence of falls yet a lower 3-year all-cause mortality, and these associations persisted regardless of baseline polypharmacy status. In the hyper-polypharmacy subgroup, KM left fall risk unchanged but still conferred a survival advantage. The absence of significant interaction terms indicates that KM neither amplifies nor attenuates the effect of polypharmacy on either outcome; rather, its mortality benefit appears broadly applicable, whereas the excess falls likely reflect enhanced mobility and survivor bias. Prospective studies with granular medication data and detailed KM exposure—including uninsured herbal prescriptions—are warranted to determine whether specific KM components can simultaneously reduce drug burden and adverse clinical events in diverse geriatric populations.