19.3 Epidemiology of Chronic Wounds
Key Takeaways
- Incidence counts new cases in a population at risk over a period of time, while prevalence counts all existing cases at a point in time (point prevalence) or over a period (period prevalence); for a stable condition, prevalence is approximately incidence multiplied by average duration.
- Chronic wounds affected about 16.3% of Medicare beneficiaries (10.5 million people) in 2019, up from 14.5% (8.2 million) in 2014, according to Carter and colleagues.
- The IDF Diabetes Atlas (11th edition, 2025) estimates 589 million adults aged 20 to 79 with diabetes worldwide, projected to reach 853 million by 2050, and the lifetime risk of a diabetic foot ulcer is about 19% to 34%.
- Diabetic foot outcomes are serious: pooled 5-year mortality is about 30.5% after a diabetic foot ulcer, 46.2% after minor amputation, and 56.6% after major amputation, and most diabetes-related amputations are preceded by a foot ulcer.
- Facility-acquired pressure injury rates are used as quality indicators, and the Agency for Healthcare Research and Quality has estimated that more than 2.5 million people in the United States develop pressure injuries each year.
19.3 Epidemiology of Chronic Wounds
Core Clinical Principle: Epidemiology tells wound specialists how common wounds are, who gets them, how often they recur, and what they cost. These numbers justify prevention programs, guide resource planning, and help patients understand the seriousness of conditions such as diabetic foot ulcers.
The CWSP outline lists epidemiology in Professional Issues. Research design and statistics used to evaluate treatments, such as relative risk and number needed to treat, are covered in the evidence-based practice section.
Measures of Disease Frequency
| Measure | Definition | Wound Care Example |
|---|---|---|
| Incidence (cumulative) | New cases during a period ÷ population at risk at the start | New pressure injuries during a hospital stay ÷ patients admitted without one |
| Incidence rate (density) | New cases ÷ total person-time at risk | New pressure injuries per 1,000 patient-days |
| Point prevalence | All existing cases at one time ÷ population at that time | Patients with any pressure injury on survey day ÷ all patients surveyed |
| Period prevalence | All cases existing at any time during a period ÷ average population | Patients with a venous leg ulcer during a year |
| Facility-acquired prevalence | Existing cases that developed after admission ÷ patients surveyed | Hospital-acquired pressure injuries on survey day |
| Recurrence rate | Healed wounds that reopen within a set time ÷ healed wounds | Diabetic foot ulcers recurring within 1 year |
Relationship: For a condition in steady state, prevalence ≈ incidence × average duration. A treatment that shortens healing time lowers prevalence even if incidence stays the same, while a treatment that keeps people alive longer with chronic wounds can raise prevalence.
Worked example: A 40-bed unit admits 200 patients without pressure injuries in a month, and 6 develop new injuries. Cumulative incidence is 6 ÷ 200 = 3%. On a single survey day, 5 of 38 patients have a pressure injury of any origin: point prevalence is 5 ÷ 38 ≈ 13%.
Other Useful Concepts
- Crude versus age-adjusted rates: Adjusting allows fair comparison between populations with different age structures.
- Risk factors, confounding, and bias: Observational data can suggest associations (for example, smoking and poor healing) but may be confounded by other factors.
- Study designs: Cross-sectional surveys measure prevalence, cohort studies measure incidence and risk, and case-control studies compare exposures in people with and without a condition.
- Surveillance and benchmarking: Standardized definitions and repeated measurement let facilities compare their rates over time and against peers.
The Burden of Chronic Wounds
| Statistic | Value | Source |
|---|---|---|
| Medicare beneficiaries with a chronic wound, 2014 | 14.5% (8.2 million) | Nussbaum and colleagues, 2018 |
| Medicare beneficiaries with a chronic wound, 2019 | 16.3% (10.5 million) | Carter and colleagues, 2023 |
| Adults aged 20–79 with diabetes worldwide, 2024 | 589 million (11.1%); projected 853 million by 2050 | IDF Diabetes Atlas, 11th edition (2025) |
| People with diabetes in the United States, 2021 | 38.4 million (11.6% of the population) | CDC National Diabetes Statistics Report |
| Lifetime risk of diabetic foot ulcer | About 19% to 34% | Armstrong, Boulton, and Bus, 2017 |
| Diabetic foot ulcer recurrence | About 40% within 1 year, about 60% within 3 years, about 65% within 5 years | Armstrong, Boulton, and Bus, 2017 |
| Diabetes-related amputations preceded by a foot ulcer | About 84% | Pecoraro and colleagues, 1990 |
| Pooled 5-year mortality | Diabetic foot ulcer 30.5%; Charcot 29.0%; minor amputation 46.2%; major amputation 56.6% | Armstrong and colleagues, 2020 |
| People in the United States who develop pressure injuries each year | More than 2.5 million | AHRQ |
| Global deaths from burns each year | About 180,000 | World Health Organization |
Venous and Arterial Disease
- Venous disease causes most leg ulcers (commonly estimated at about 70%), with high recurrence without long-term compression.
- Peripheral artery disease affects more than 200 million people worldwide, and many are undiagnosed because they have atypical or no symptoms. Chronic limb-threatening ischemia carries high amputation and mortality risk.
- Mixed arterial and venous disease is common in older patients, which is why arterial screening before compression matters.
Pressure Injuries
Pressure injuries are common in hospitals, long-term care, and home care, and facility-acquired rates are tracked as quality indicators. In the United States, the Agency for Healthcare Research and Quality has estimated that more than 2.5 million people develop pressure injuries each year. Hospital-acquired stage 3 and 4 injuries affect payment through CMS hospital-acquired condition policies.
Disparities
Rates of diabetes-related amputation are higher among Black, Hispanic, and American Indian and Alaska Native populations and in rural and low-income communities in the United States, reflecting differences in access to preventive foot care, vascular evaluation, and specialty referral. Recognizing these patterns supports targeted screening, outreach, and multidisciplinary limb preservation programs.
Using Epidemiology in Practice
- Plan services: Estimate how many patients with diabetes in a practice need high-risk foot care.
- Measure quality: Track facility-acquired pressure injury incidence per 1,000 patient-days.
- Counsel patients: Explaining that diabetic foot ulcers carry 5-year mortality comparable to many cancers helps patients understand why prevention matters.
- Evaluate programs: Compare amputation or recurrence rates before and after a limb preservation program, adjusting for population changes.
Clinical Traps
Trap 1: Confusing Incidence With Prevalence
A survey-day count of existing pressure injuries is prevalence, not incidence. It includes injuries present on admission unless facility-acquired cases are separated.
Trap 2: Treating a Healed Diabetic Foot Ulcer as Cured
With about 40% recurrence in the first year, a healed foot is in remission and needs ongoing protective footwear and surveillance.
During March, a 30-bed unit admits 150 patients who have no pressure injuries on admission, and 9 of them develop a new pressure injury during their stay. On March 15, a one-day survey finds that 6 of the 28 patients on the unit have a pressure injury, 2 of which were present on admission. What are the cumulative incidence for March and the point prevalence on March 15?
A wound center introduces a treatment protocol that halves the average time to heal venous leg ulcers but does not change how many new ulcers develop each year. If the population is otherwise stable, what is the expected effect on ulcer prevalence?
A patient with type 2 diabetes asks how serious his newly healed diabetic foot ulcer is. Which statement is supported by published epidemiologic data?