Frailty describes a clinical condition characterized by diminished physiological reserves. A frail person can still function under everyday conditions—but even the slightest stress can trigger a crisis that a non-frail person would easily handle. In geriatrics, frailty is thus the crucial link between chronological age and biological age. The article on geriatrics and geriatric medicine provides an overview of the entire field.
Three distinctions are important:
- Frailty is not the same as multimorbidity: A person can have many diseases and still not be frail—and vice versa.
- Frailty is not the same as disability: Disability describes what a person can no longer do. Frailty describes how well a person can cope with stress.
- Frailty is not the same as sarcopenia: Sarcopenia (muscle loss) is a central component, but frailty encompasses more: it also includes cognitive, nutritional, and social dimensions. Cognitive changes such as mild cognitive impairment (MCI) can exacerbate frailty, and vice versa.
→ On the specific significance of muscle loss in old age: Sarcopenia — Recognizing and Stopping Muscle Loss.
Two validated models dominate clinical practice. Both have their place in different settings.
The Fried Phenotype
In 2001, Linda Fried and colleagues defined five criteria. Those who meet three or more are considered frail; one to two, pre-frail; and none, robust.
- Unintentional weight loss: More than 4.5 kilograms or 5 percent of body weight in the past year. This weight loss is often a sign of malnutrition in older adults.
- Fatigue: Subjectively reported fatigue on three or more days per week.
- Weakness: Reduced handgrip strength, measured with a dynamometer.
- Slowness: Slowed walking speed over four meters.
- Low physical activity: Significantly reduced daily activity, which in extreme cases can lead to immobility in older adults.
The Fried phenotype is particularly useful in research and preoperative evaluation because it can be measured objectively and reproducibly.
The Clinical Frailty Scale (CFS)
Developed by Kenneth Rockwood, the CFS is a 9-point scale that can be clinically assessed in just a few minutes—without the need for specialized equipment. It ranges from CFS 1 (“very fit”) through CFS 5 (“mildly frail”) to CFS 9 (“terminally ill”).
The CFS has gained widespread acceptance worldwide because it is immediately available in hectic clinical settings—such as the emergency department, intensive care unit, and preoperative clinic—while still providing highly significant prognostic information. In numerous studies, a CFS score above 5 has been associated with significantly increased mortality, longer hospital stays, and a higher rate of functional decline following hospitalization. Structured frailty screening describes which specific tests are used in this process.
As a patient or family member, you can ask about the Clinical Frailty Scale whenever a major treatment decision is being made: “Was the CFS assessed, and what was the result?” This is not a question for specialists—it is a fundamental question in modern geriatric medicine.
- People aged 65 to 74: About 4 to 8 percent are frail, and another 30 percent are pre-frail.
- People aged 75 to 84: About 15 percent are frail.
- People over 85: 30 to 50 percent are frail.
- In nursing homes: Over 60 percent of residents meet the criteria for frailty.
Frailty is thus one of the most common syndromes in geriatric medicine—and one of the least frequently documented. Many discharge summaries mention diabetes in older adults, hypertension, and atrial fibrillation in older adults—but not a word about frailty. This is a systemic gap.
Frailty is not just an epidemiological observation—it changes the entire clinical decision-making process:
- Surgical planning: Frailty-adjusted risk assessment is superior to the conventional ASA score. A CFS score of 5 or higher should be factored into every risk-benefit analysis for elective procedures. Details on this can be found in the article on surgical risk in older adults.
- Drug therapy: In frail patients, the risk-benefit ratios shift: Some guideline-based therapies (strict blood glucose control, aggressive blood pressure reduction) result in net harm in the presence of frailty. The issue of polypharmacy in older adults also plays a central role here.
- Rehabilitation: Frail patients benefit particularly—and specifically—from early geriatric rehabilitation. Standard protocols are often ineffective.
- Prognosis: In many cohort studies, frailty is the strongest single predictor of 1-year mortality—stronger than many specific diagnoses, including existing heart failure in older adults.
- Risk of delirium in the hospital: Frail patients are significantly more likely to develop delirium following procedures or acute illnesses. Targeted delirium prevention is therefore standard practice in geriatric care.
- End-of-life decision-making: In cases of severe frailty (CFS 7–8), treatment goals shift toward quality of life and symptom management. These discussions must take place early on—and should ideally be supported by an advance directive.
→ For preoperative assessment and risk modification: Surgical risk in older adults.
→ How early geriatric rehabilitation works, especially in frail patients: Early geriatric rehabilitation.
Frailty is multifactorial. The most important mechanisms—and thus the most important targets for prevention and treatment—are:
- Sarcopenia: The age-related loss of muscle mass and muscle strength. Without targeted training, this amounts to approximately 1 to 2 percent per year starting at age 50. For more on this, see the article on sarcopenia.
- Malnutrition: Specifically, protein deficiency: Most older adults do not meet the recommended daily protein intake (1.0 to 1.2 g per kg of body weight). For detailed background information, see the article on malnutrition in older adults.
- Chronic inflammatory burden: Elevated levels of interleukin-6, CRP, and TNF-alpha—a phenomenon often referred to as “inflammaging.”
- Hormonal changes: Decline in testosterone, growth hormone, and vitamin D. A confirmed vitamin D deficiency is closely linked to osteoporosis in older adults.
- Lack of physical activity: The most important modifiable cause. Every day of reduced activity contributes to frailty—a vicious cycle that, in extreme cases, leads to immobility in old age.
- Social isolation: Loneliness is an independent risk factor—biologically measurable, not merely psychologically relevant. There are also close links to depression in old age.
- Multimorbidity and polypharmacy: Not identical to frailty, but one of its strongest driving forces. Regarding medication reduction in older adults: deprescribing.
The most significant misconception: that frailty is a permanent condition. The evidence contradicts this. Studies show that about one-third of pre-frail patients return to a robust state within a year—and even in cases of severe frailty, stabilization or partial reversal is possible when the right interventions work together.
What the evidence supports
- Progressive strength training: By far the most powerful single intervention. Studies show strength gains of 30 to 100 percent in just a few months—even among 85- and 90-year-olds.
- A high-protein diet: With a focus on spreading intake throughout the day. Protein-rich breakfasts are more important than a single large dinner.
- Vitamin D supplementation for confirmed deficiency: Not a one-size-fits-all solution. A deficiency is often associated with osteoporosis in older adults and an increased risk of falls.
- Medication review: Deprescribing not only reduces side effects but often directly improves energy levels and muscle strength.
- Treatment of hidden conditions: Anemia, thyroid disorders, depression in older adults, obstructive sleep apnea syndrome—each is a potential contributor to frailty. Undiagnosed dementia in older adults or mild cognitive impairment (MCI) can also mask the picture of frailty.
- Fall prevention: Since frail patients have a significantly increased risk of falling—with consequences such as a femoral neck fracture in older adults—targeted fall prevention is one of the most important supportive measures.
- Social activity: Participation, volunteer work, structured group programs—demonstrably effective.
- Geriatric Assessment as a Framework: Geriatric assessment is not a single intervention, but rather the tool used to identify the appropriate interventions. It systematically assesses mobility, cognition, nutritional status, fall risk, and medication.
→ What targeted nutritional interventions for older adults look like: Malnutrition in older adults.
→ Why lack of exercise and immobility are more dangerous than many people think: Immobility in older adults.
For family members who want to realistically assess the condition of an older family member, the following everyday observations can be helpful:
- Can he or she walk 400 meters without stopping?
- Climb a flight of stairs without a handrail?
- Stand up from a deep armchair without using the armrests?
- Carry a shopping bag with a few groceries?
- Has there been unintentional weight loss in the last six months?
- Has their activity level noticeably decreased compared to last year?
- Does the person report persistent fatigue?
- Are there signs of urinary incontinence in older adults? This symptom, which is often kept private, can also be a sign of declining physical reserves.
If the answers to several of these questions—particularly the last ones—are “no” or “yes,” a geriatric evaluation is warranted. A structured frailty screening provides initial indications.
Frailty is not always obvious. The following situations are good reasons to seek a geriatric second opinion:
- Before any elective major surgery in patients over 75—surgical risk in older adults depends significantly on frailty status.
- After a hospital stay with visible functional decline
- In cases of repeated falls or newly developed unsteadiness while walking—for more information, see the article on falls in older adults
- In cases of unintentional weight loss of more than 5 percent over six months
- In cases of polypharmacy involving five or more long-term medications
- When a serious diagnosis such as cancer or heart failure in older adults requires treatment decisions
In these situations, the geriatrician brings a perspective that is often missing in organ-specific specialties: the question of how resilient the patient is as a whole system—and which interventions will be most effective before the next stressor arises.
→ We describe exactly which tests are used in frailty screening in the article “Frailty Screening—Practical Implementation.”
