The "two flights of stairs" rule: why preoperative functional capacity is more than a binary test

"Can you climb two flights of stairs without stopping?"

Key takeaways for faster decisions#

A finer stratification than the 4-MET cutoff

• The "two flights of stairs" question aims to estimate METs, and the 4-MET threshold has long served as a decision driver in surgical risk stratification.
• The study challenges the binary approach ("can or cannot") and demonstrates a dose-response relationship across five categories: MET 1, 2–3, 4–5, 6–8, and 9 or above.
• Risk does not merely "begin" below 4 METs: it increases progressively as functional capacity declines.

Self-reported functional capacity predicts outcomes up to 1 year

• Physical fitness reported at the preoperative assessment remains a significant predictor of mortality up to 365 days after surgery.
• The absolute risk of dying 1 year after elective surgery is significantly elevated and distinct at each MET level compared to MET 9 or above.
• This association suggests that functional capacity in METs is a marker of the patient's underlying resilience and health trajectory.

"Days at Home Alive" (DAH) and the weight of the short term

• Lower MET levels were associated with significantly fewer days at home in the following year, reflecting hospitalization, readmissions, and mortality.
• The relative impact on mortality was greater in the first 30 days than between 31 and 365 days.
• Surgery represents a massive physiological burden, with approximately 8 million deaths annually worldwide, and the patient's "reserve" is the primary defense against the initial impact.

Well-conducted subjectivity and looking ahead

• Although CPET is the gold standard, it requires specialized equipment and personnel and may be impractical for routine screening.
• When properly conducted, self-reported assessment is extremely robust, especially with the anesthesiologist's help in correlating physical activity to the correct MET level.
• Functional capacity is a modifiable risk factor that demands attention: if we can identify high-risk patients months before elective surgery, what are we doing to improve their functional capacity before they reach the operating table?

Why does this question appear in nearly every preanesthetic assessment?#

In preanesthetic assessments, we frequently ask the same question: "Can you climb two flights of stairs without stopping?" This simple question aims to estimate the patient's metabolic equivalents of task (METs).

For a long time, the 4-MET threshold served as a decision driver in surgical risk stratification. Yet the validity of these self-reported assessments has been the subject of intense debate in perioperative medicine, with experts questioning whether subjective measures can truly predict objective outcomes.

The study that goes beyond "can or cannot"#

The cohort study with 38,293 patients, "Impact of Preoperative Functional Capacity on Postoperative Mortality and Morbidity: A Prospective Cohort Study", recently published in the journal Anesthesiology, provides a definitive answer.

By going beyond the simple "can or cannot," the researchers show that functional capacity is not merely a hurdle to be cleared: it functions as a high-resolution map of the patient's survival trajectory over the following year.

Below, we present the most impactful findings from this study conducted at two major centers in Sweden.

1) Why stratify into groups (rather than treat it as a binary threshold)?#

For years, perioperative guidelines relied on a binary threshold: patients with less than 4 METs were considered to have "poor" functional status.

This study challenges that simplicity by demonstrating a dose-response relationship across five distinct categories:

• MET 1
• 2–3
• 4–5
• 6–8
• 9 or above

The data show that risk does not merely "begin" below 4 METs; it increases progressively as functional capacity declines.

By using more detailed categories, clinicians can move toward much more precise risk stratification, abandoning the "one-size-fits-all" approach.

2) What does the 1-year analysis show about survival?#

Perhaps the most striking finding is that physical fitness reported by the patient on the day of preoperative assessment remains a significant predictor of mortality up to 365 days after surgery.

Although it is common to think of functional capacity as a measure of tolerance to the immediate physiological stress of the operating room, the study suggests it is a marker of the individual's underlying resilience.

"Indeed, the absolute risk of dying 1 year after elective surgery is significantly elevated, and distinct, at each MET level compared with MET 9 or above."

This long-term association indicates that self-reported functional capacity in METs is not merely the result of a surgical "stress test"; it is a fundamental indicator of the patient's health trajectory.

3) What are "Days at Home Alive" (DAH) and why does it matter?#

Survival is the primary goal, but for patients, the quality of that survival matters as much as the time itself.

The study used a patient-centered outcome called Days at Home Alive (DAH), which accounts for:

• length of hospital stay,
• readmissions,
• mortality.

The results were clear: lower levels of self-reported functional capacity in METs were associated with significantly fewer days at home during the following year.

This means that low functional capacity does not only increase the risk of death; it increases the likelihood of a year marked by hospital returns and complications. This is a powerful data point for patient counseling, as it translates "risk" into an intuitive concept: your time at home.

4) Why is the impact greater in the acute phase?#

Although risk persists for a year, the study found that the impact of functional capacity is most acute in the short term.

The relative effect of self-reported functional capacity in METs on mortality was greater in the first 30 days compared to the period between 31 and 365 days.

This reinforces the idea that surgery represents a massive physiological burden, resulting in approximately 8 million deaths annually worldwide, and the patient's "reserve" is their primary defense against this initial impact.

5) What does this study say about the "power of guided subjectivity"?#

Despite efforts to implement objective measures such as the cardiopulmonary exercise test (CPET), this study proves that self-reported data is extremely robust when properly conducted.

Although CPET is the gold standard, it requires specialized equipment and personnel, which is often impractical for routine screening.

By relying on the anesthesiologist's help to correlate the patient's physical activity level to the correct MET level, we can achieve high-quality risk assessment without the need for a treadmill or complex equipment.

Looking ahead#

The evidence is now compelling: functional capacity is a modifiable risk factor that demands our attention.

As we move toward more personalized perioperative medicine, we must ask ourselves: If we can identify these high-risk patients months before elective surgery, what are we doing to improve their functional capacity before they reach the operating table?