The Polypharmacy Problem in Japan's Elderly — Why 40% Take 5 or More Medications
About 40% of Japanese adults aged 75+ are prescribed 5 or more medications, and roughly 25% take 7 or more. Once the threshold of 6 drugs is crossed, adverse drug events increase significantly. Prescribing cascades, fragmented care, and psychological barriers to deprescribing perpetuate this structural problem.
TL;DR
- About 40% of those aged 75+ are prescribed 5 or more drugs, with adverse drug events increasing significantly above 6 medications
- Multiple prescribers and prescribing cascades structurally reproduce polypharmacy
- Japan's 2024 fee schedule revision expanded deprescribing incentives, but the utilization rate remains below 10% at 95% of hospitals
What's Happening
40% of those 75+ are prescribed 5+ drugs, and adverse events spike sharply above 6 medications.
Among Japanese adults aged 75 and over, approximately 40% are prescribed 5 or more medications (this figure is from 2016 data widely cited as the basis for MHLW guidelines; current prescribing patterns may have shifted). Even when limited to 7 or more, about 25% — one in four — meet the threshold.
Why does polypharmacy grow, and what does it cause?
Structural Drivers of Polypharmacy
Avg. 4–5 conditions in those 75+
Fragmented care without gatekeeping
Side effect → misdiagnosed → new drug
Both patients and doctors fear deprescribing
The 6-drug threshold
ADEs increase significantly at 6+ medications (MHLW Guidelines 2018)
Adverse Event Chain
This is not simply a matter of "too many pills." The Ministry of Health, Labour and Welfare (MHLW) stated in its 2018 "Guidelines for Appropriate Medication Use in the Elderly" that adverse drug events increase significantly at 6 or more medications. Adverse drug events (ADEs) rise proportionally with the number of drugs, and 6 is a critical threshold.
The consequences are severe. University hospital surveys indicate that roughly 10% of elderly inpatients experience ADEs. Fall risk increases 1.28-fold at 5 or more medications, reaching 1.40-fold when benzodiazepines are included. One in three adults aged 65+ falls at least once per year, and approximately 250,000 suffer hip fractures annually. Falls and fractures are the fourth-leading cause of long-term care needs (13.0% of all cases), making polypharmacy a hidden gateway to dependency.
Furthermore, patients taking 7 or more drugs face a hazard ratio of 3.94 for unplanned 30-day readmission. If medication problems are not resolved at discharge, patients return — a vicious cycle that erodes both healthcare costs and quality of life.
The Japan Geriatrics Society revised its Guidelines for Safe Drug Therapy in the Elderly 2025 for the first time in a decade, reaffirming that "5 to 6 or more drugs should be considered the benchmark for polypharmacy." The problem is recognized both academically and institutionally. Yet the structure remains unchanged.
Background and Context
Three structural mechanisms — multiple prescribers, prescribing cascades, and deprescribing barriers — perpetuate polypharmacy.
Three Structural Drivers of Polypharmacy
Why do medications keep accumulating for the elderly? Three structural mechanisms are at work.
Structure 1 — Multi-morbidity and multiple prescribers. Adults aged 75+ have an average of 4 to 5 chronic conditions: hypertension, diabetes, dyslipidemia, osteoporosis, insomnia. Each condition is treated by a different specialist who prescribes independently. Japan's healthcare system operates on a free-access principle — patients can visit any clinic or hospital without a referral. The result is that no one oversees the total prescription picture.
A study of community-dwelling elderly in Japan confirmed that polypharmacy risk increases significantly with the number of medical institutions visited. The absence of a built-in mechanism for viewing the "sum" of all prescriptions creates fertile ground for polypharmacy.
Structure 2 — The prescribing cascade. A side effect of Drug A (e.g., edema) is mistaken for a new condition, and Drug B (a diuretic) is added. Drug B's side effect (dehydration) leads to Drug C — and the chain continues.
A typical example: statin (for dyslipidemia) → muscle pain as side effect → NSAID prescribed → edema as side effect → loop diuretic prescribed → dehydration. One drug cascades into four or five. The National Center for Geriatrics and Gerontology warns: "That symptom might be a side effect of your medication."
Structure 3 — Psychological barriers to deprescribing. Patients worry: "If I stop a prescribed medication, might my condition worsen?" Physicians worry: "If I discontinue another doctor's prescription and something goes wrong, will I be held responsible?" The result is that no one reduces medications. Drugs accumulate while the system lacks a built-in force for reduction.
Fee Schedule Reforms and Deprescribing Incentives
Policy has not been idle in addressing this structure.
The 2016 fee schedule revision introduced the Drug Comprehensive Evaluation Adjustment Fee. When a patient is prescribed 6 or more oral medications and the total is reduced by 2 or more through comprehensive evaluation, the fee can be billed. Pharmacies also received the "Medication Adjustment Support Fee," creating incentives for pharmacist-initiated deprescribing proposals.
The 2024 revision further relaxed requirements, removing the mandatory conference requirement and allowing billing when multidisciplinary medication evaluation occurs within routine workflows.
But what is the reality? According to GHC's healthcare management analysis, 95% of hospitals have an utilization rate below 10% for this adjustment fee. The system exists but is barely used. The fee (250 points = ¥2,500) does not adequately compensate the workload of multi-professional review, patient persuasion, and cross-institutional coordination.
Japan's Structural Uniqueness in International Perspective
Polypharmacy is a common challenge across developed nations, but Japan's structure has distinctive features.
WHO has identified polypharmacy in the elderly as a global public health challenge and recommends reducing inappropriate polypharmacy. In the UK, the NHS GP system provides a gatekeeper function where a single physician oversees the full prescription picture. France's "médecin traitant" (family doctor) system ensures centralized prescription management.
Japan's free-access system excels in patient choice. However, its flip side is that prescription information fragmentation is structurally embedded. Efforts to share prescription data through medication notebooks (okusuri techo) and the online qualification verification system are advancing, but have not yet reached the stage of "seeing all prescriptions at a glance."
Reading the Structure
Limitations of fee-schedule incentives and the need for cross-system prescription data integration.
It should be noted that for elderly patients with multiple chronic conditions, 6 or more medications may be clinically necessary. The problem is not the number of drugs per se, but the structure in which prescriptions accumulate without regular reassessment of their appropriateness.
What the polypharmacy problem reveals is not a simple "too many drugs, so let's reduce them" story, but a structural contradiction inherent in the design of Japan's healthcare system itself.
Structure 1 — The free-access vs. prescription fragmentation trade-off. The system enabling patients to freely visit multiple medical institutions is excellent for accessibility. But without a designated "integrator" to oversee the complete prescription picture, medications accumulate independently across specialties. Real-time prescription sharing via the My Number insurance card has been rolling out since 2024, but there is a vast gap between information being "visible" and it being "acted upon."
Structure 2 — The weak incentive of adjustment fees. The Drug Comprehensive Evaluation Adjustment Fee rewards deprescribing, but 250 points is insufficient for the cost of multidisciplinary review, patient persuasion, and cross-institutional coordination. Moreover, when prescriptions originate from multiple institutions, it is unclear who should take the initiative. The incentive design is not merely "weak" — it is "missing the target" relative to the problem's structure.
Structure 3 — The asymmetry between prevention and treatment. Resolving polypharmacy can prevent falls, fractures, and hospitalizations through reduced ADEs, potentially lowering healthcare costs. But preventive effects are invisible — they manifest as "events that didn't happen" — and cannot easily fit into treatment-oriented reimbursement structures. The structural undervaluation of prevention resonates with the broader structure of healthcare spending.
These three structures, beyond the phenomenon of polypharmacy, illuminate fundamental challenges in Japan's healthcare system: information fragmentation, incentive misalignment, and the undervaluation of prevention.
Without verifying the cost-effectiveness of deprescribing interventions through EBPM methods, visualizing intervention pathways through Logic Models, building integrated prescription data infrastructure, and substantially strengthening family physician functions — the "40%" figure will not budge.
Related Guides
- Introduction to EBPM — What is Evidence-Based Policy Making?
- Logic Model Practical Guide — Visualizing Project Design
- The Economics of Preventive Medicine — Why "Preventing" Is More Rational Than "Curing"
References
Guidelines for Appropriate Medication Use in the Elderly (General Edition) — Ministry of Health, Labour and Welfare. Ministry of Health, Labour and Welfare
Overview of Social Medical Care Procedure Statistics (FY2022) — Ministry of Health, Labour and Welfare. Ministry of Health, Labour and Welfare
Number of consulting medical institutions and risk of polypharmacy in community-dwelling older people under a healthcare system with free access — Komiya H, Umegaki H, Asai A, et al.. BMC Geriatrics
Polypharmacy Management in Older Patients — Dagli RJ, Sharma A.. Mayo Clinic Proceedings
Polypharmacy is a risk factor for hospital admission due to a fall — Dhalwani NN, Fahami R, Sathanapally H, et al.. BMC Public Health
Polypharmacy and Falls — Healthy Longevity Net Editorial Team. Japan Foundation for Aging and Health
