ABSTRACT
Aim
This study aimed to identify demographic and clinical factors associated with advanced‐stage pressure injury (PI) classification among hospitalised patients diagnosed with PIs using the Health Insurance Review and Assessment Service (HIRA) patient sample database.
Design
This secondary data analysis was approved by the Institutional Review Board of K University (IRB No. 2020‐0266). Public data were analysed using SAS Enterprise Guide on a designated computer, and all procedures complied with data security and confidentiality requirements.
Methods
A secondary analysis was conducted using the HIRA patient sample database from 2017 to 2019. Patients diagnosed with pressure injuries were classified into a mild‐stage group (Stages 1–2) and an advanced‐stage group (Stages 3–4). Multivariable logistic regression analysis was performed to identify factors associated with advanced‐stage pressure injury classification (Stage 3–4 vs. Stage 1–2), and odds ratios (ORs) with 95% confidence intervals (CIs) were estimated.
Results
Male patients had higher odds of being classified as having advanced‐stage pressure injuries than female patients (OR = 1.25). The odds of advanced‐stage pressure injury classification increased by 1.02 for each one‐year increase in age and by 1.02 for each additional day of hospitalisation. Patients with urinary incontinence and malnutrition had 3.32‐fold and 2.76‐fold higher odds, respectively, of being classified as having advanced‐stage pressure injuries than those without these conditions (p < 0.001).
Conclusion
Sex, age, length of hospital stay and specific comorbidities were significantly associated with advanced‐stage pressure injury classification among hospitalised patients with pressure injuries. Urinary incontinence and malnutrition showed particularly strong associations with advanced‐stage classification. These findings may support the early identification of patients who are more likely to present with advanced‐stage pressure injuries and inform targeted assessment and management strategies in clinical practice. Because this study was based on cross‐sectional administrative claims data, the findings should be interpreted as associations with advanced‐stage classification rather than evidence of temporal progression or causation.
Patient or Public Contribution
This study utilised secondary administrative data from a nationally representative sample provided by the Health Insurance Review and Assessment Service (2017–2019). No patients or members of the public were directly involved in the design or conduct of this study because the analyses were based on de‐identified administrative claims data.
Keywords: hospitalised patient, malnutrition, pressure injury, urinary incontinence
1. Introduction
In‐hospital patient safety incidents include wrong‐site surgery, patient falls, physical restraint‐related injuries and pressure injuries. Among these, pressure injuries are localised damage to the skin and underlying tissue resulting from prolonged pressure or repeated friction and shear forces applied to specific body areas (Dallow et al. 2024). Pressure injuries are classified according to the extent of tissue damage, with advanced‐stage pressure injuries characterised by substantial tissue destruction and considerable clinical burden (Cho et al. 2020). In particular, advanced‐stage pressure injuries (Stages 3–4) may result in serious complications, including infection, osteomyelitis and sepsis, and can ultimately contribute to mortality because of chronic wounds and extensive tissue destruction (WHO 2021). Therefore, early assessment and appropriate management of pressure injuries, including timely wound care, infection prevention and appropriate dressing interventions, are essential to prevent progression to advanced‐stage pressure injuries and improve patient outcomes (Bustamante and Martinez 2025; Mervis and Phillips 2019).
The Practical Guidelines for Pressure Injury Nursing revised by the Hospital Nurses Association in 2020 and the International Clinical Practice Guideline published in 2019 recommend comprehensive assessment of patient characteristics, including age, underlying diseases, nutritional status, surgical history and urinary and faecal incontinence, because these factors may be associated with pressure injury severity (Kottner et al. 2020; Park et al. 2019). Accordingly, a multidisciplinary approach that considers nutritional status, comorbid conditions and overall clinical severity is essential for the assessment, prevention and management of pressure injuries (Kuikko et al. 2024). Furthermore, pressure injury prevention and management are important indicators of nursing quality and patient safety (Dallow et al. 2024; Kim, Hwang, et al. 2017). Indeed, the occurrence and severity of pressure injuries are widely recognised as nursing‐sensitive indicators and key measures of healthcare quality (Gaspar et al. 2022; Korea Institute for Healthcare Accreditation 2018).
Previous studies have examined nursing care practices for pressure injuries among critically ill patients, including those requiring invasive mechanical ventilation and have highlighted the contextual challenges associated with managing severe pressure injuries in clinical settings (Bustamante and Martinez 2025). In addition, burnout and emotional exhaustion among nurses have been reported to adversely affect patient safety and the quality of pressure injury prevention and management (Gómez‐Urquiza et al. 2020; Han et al. 2019; Petrelli et al. 2020). Studies conducted in South Korea have similarly identified pressure injuries as an important patient safety issue (Kim et al. 2019; Kim, Kim, et al. 2017). Cho et al. (2020) reported that 12.7% of hospitalised patients in university hospitals had pressure injuries, and 19.1% of these patients were classified as having advanced‐stage pressure injuries (Stages 3–4). These findings suggest that a substantial proportion of patients with pressure injuries experience severe tissue damage requiring intensive clinical management.
Advanced‐stage pressure injuries are associated with delayed wound healing, prolonged hospitalisation, increased healthcare costs and poorer clinical outcomes. Severe pressure injuries often require intensive wound care, greater nursing resource utilisation and multidisciplinary management and may lead to serious complications such as infection, osteomyelitis and sepsis (Dallow et al. 2024; WHO 2021). Because pressure injuries are classified according to identifiable stages, early identification of patients who are more likely to present with advanced‐stage pressure injuries is essential for improving patient outcomes. Despite the clinical significance of pressure injury severity, evidence regarding factors associated with advanced‐stage pressure injuries among patients already diagnosed with pressure injuries remains limited, particularly at the national level. Most previous studies have focused on pressure injury occurrence in general hospitalised populations or have been conducted in single institutions, thereby limiting the generalisability of their findings. Furthermore, demographic and clinical factors associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage classification (Stages 1–2) have not been sufficiently investigated using nationally representative data. Therefore, population‐based research is needed to identify factors associated with advanced‐stage pressure injury classification among patients with existing pressure injuries and to support the development of targeted prevention and management strategies.
The primary aim of this study was to identify demographic and clinical factors associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage pressure injury classification (Stages 1–2) among hospitalised Korean patients who had already been diagnosed with pressure injuries using nationally representative data from the Health Insurance Review and Assessment Service (HIRA) from 2017 to 2019. As secondary descriptive aims, this study sought to characterise the clinical profiles of patients with pressure injuries by examining disease distributions, treatment patterns and clinical department distributions. By comparing patients with advanced‐stage pressure injuries (Stages 3–4) and those with mild‐stage pressure injuries (Stages 1–2), this study aimed to identify demographic and clinical characteristics associated with advanced‐stage pressure injury classification and to provide evidence to support targeted prevention and management strategies for patients with severe pressure injuries. The research question guiding this study was: ‘Among hospitalised patients already diagnosed with pressure injuries, what demographic and clinical factors are associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage pressure injury classification (Stages 1–2)?’
2. Methods
2.1. Study Design and Participants
This study was a secondary analysis of nationally representative claims data designed to identify demographic and clinical factors associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage pressure injury classification (Stages 1–2) among hospitalised patients who had already been diagnosed with pressure injuries (PIs), using the Health Insurance Review and Assessment Service (HIRA) patient sample database from 2017 to 2019.
Patient sample data collected by HIRA for reimbursement purposes between January 1, 2017, and December 31, 2019, were used in this study. The study population comprised patients with pressure injuries who were admitted to tertiary general hospitals, general hospitals and hospitals nationwide and were covered by the National Health Insurance or Medical Aid programmes in South Korea. Eligible participants met the following inclusion criteria: (1) adults aged 18 years or older; (2) a hospital stay of at least three days; and (3) a diagnosis of a pressure injury.
Data were extracted from the HIRA database using pressure injury diagnosis codes, including AL890 (Stage 1), AL891 (Stage 2), AL892 (Stage 3), AL893 (Stage 4) and AL899 (Unstageable/Unclassified). According to the National Pressure Injury Advisory Panel (NPIAP) classification system, pressure injury severity is categorised into four stages. Stage 1 is characterised by intact skin with non‐blanchable erythema; Stage 2 involves partial‐thickness skin loss; Stage 3 involves full‐thickness skin loss extending into subcutaneous tissue; and Stage 4 involves full‐thickness tissue loss with exposed bone, tendon or muscle.
For the primary analysis, the study population consisted exclusively of patients who had already been diagnosed with pressure injuries. The outcome variable for the multivariable logistic regression model was pressure injury severity, defined as advanced‐stage pressure injury classification (Stages 3–4) versus mild‐stage pressure injury classification (Stages 1–2). Accordingly, patients were classified into either a mild‐stage group (Stages 1–2) or an advanced‐stage group (Stages 3–4). Patients coded as AL899 (Unstageable/Unclassified) were excluded from the regression analysis because they could not be assigned to either severity category.
A total of 544,643 patient records were included in the descriptive analyses. However, only patients with classifiable pressure injury stages (Stages 1–4) were included in the multivariable logistic regression analysis comparing advanced‐stage and mild‐stage pressure injury classifications.
2.2. Variables and Measures
Variables were extracted from the Health Insurance Review and Assessment Service (HIRA) patient sample database and included demographic characteristics, length of hospital stay, pressure injury stage, comorbid conditions, clinical departments, treatment characteristics and pressure injury‐related interventions.
Pressure injury severity was classified according to the National Pressure Injury Advisory Panel (NPIAP) staging system. Patients were categorised into four stages (Stages 1–4) based on the extent of tissue damage. For the primary analysis, pressure injury severity was dichotomised into a mild‐stage group (Stages 1–2) and an advanced‐stage group (Stages 3–4). The primary outcome of the multivariable logistic regression analysis was advanced‐stage pressure injury classification (Stages 3–4) versus mild‐stage pressure injury classification (Stages 1–2) among patients who had already been diagnosed with pressure injuries.
Variables were selected a priori on the basis of previous literature and data availability within the HIRA database. Demographic characteristics, comorbid conditions, treatment characteristics and hospitalisation‐related variables were examined as factors associated with advanced‐stage pressure injury classification. Because this study was based on cross‐sectional administrative claims data, terminology implying temporal change or disease progression was avoided. Accordingly, the findings should be interpreted as associations with advanced‐stage pressure injury classification at the time of observation rather than as evidence of longitudinal progression or causation.
2.3. Data Collection
Data were collected from November 2021 to February 2022. After obtaining approval from the Institutional Review Board, customised patient sample data (Project No. M20200403435) were requested from the Health Insurance Review and Assessment Service (HIRA). The data were analysed in accordance with the aims of this study, focusing on factors associated with advanced‐stage pressure injury classification (Stages 3–4 vs. Stages 1–2) among hospitalised patients with existing pressure injuries.
2.4. Data Analysis
Data were analysed using SAS Enterprise Guide (version 7.1; SAS Institute Inc., Cary, NC, USA). To ensure the representativeness of the national population, all analyses incorporated the complex sampling design of the HIRA database, including primary sampling units (PSUs), clustering and survey weights provided by HIRA. Statistical significance was set at p < 0.05.
The general characteristics of patients, clinical departments and treatment patterns from 2017 to 2019 were analysed using descriptive statistics (frequencies and percentages) with PROC SURVEYFREQ. Differences in patient characteristics according to pressure injury classification were examined using PROC SURVEYREG for continuous variables and PROC SURVEYFREQ with the Rao–Scott chi‐square test for categorical variables.
To identify demographic and clinical factors associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage pressure injury classification (Stages 1–2) among hospitalised patients with existing pressure injuries, multivariable logistic regression analysis was performed using PROC SURVEYLOGISTIC. The dependent variable was pressure injury classification, defined as advanced‐stage pressure injury classification (Stages 3–4) versus mild‐stage pressure injury classification (Stages 1–2). Results are presented as odds ratios (ORs) with 95% confidence intervals (CIs). This analytical approach accounted for the complex survey design and provided appropriate variance estimates for the nationally representative sample.
Covariates included in the multivariable logistic regression model were selected a priori on the basis of previous literature and clinical relevance. Calendar year (2017, 2018 and 2019) was additionally included in the adjusted model to account for potential variations in coding practices and patient characteristics during the study period. To assess multicollinearity among covariates, variance inflation factors (VIFs) were examined and no evidence of problematic multicollinearity was observed (maximum VIF = 3.8). Model discrimination was evaluated using the c‐statistic, defined as the area under the receiver operating characteristic curve (AUC), which was 0.82, indicating good discriminative ability.
To evaluate the robustness of the findings, a sensitivity analysis was conducted by repeating the multivariable logistic regression after excluding cases with unspecified pressure injury stages and comparing the direction and magnitude of the estimated odds ratios.
2.5. Missing Data
Before analysis, all study variables were examined for completeness. The HIRA claims database consists of standardised administrative records with mandatory claim fields. No missing values were identified in the variables included in the present analyses after data extraction and cleaning. Therefore, no cases were excluded because of missing covariate information and neither imputation nor complete‐case analysis was required. Because this study was based on cross‐sectional administrative claims data, the findings should be interpreted as associations with advanced‐stage pressure injury classification rather than as evidence of temporal progression or causation.
2.6. Ethical Considerations
This study was approved by the Institutional Review Board of Korea University (IRB No. 2020‐0266). Access to the HIRA patient sample database was granted following review and approval of the study protocol and public data request procedures. All analyses were conducted using SAS Enterprise Guide on a designated computer in accordance with HIRA data security regulations. Following completion of the analyses, all results were returned to HIRA in accordance with its data management policies to ensure the confidentiality and protection of patient information. Because this study used de‐identified administrative claims data, the requirement for informed consent was waived by the Institutional Review Board.
3. Results
To assess multicollinearity in the multivariable logistic regression model comparing advanced‐stage pressure injury classification (Stages 3–4) with mild‐stage pressure injury classification (Stages 1–2) among patients already diagnosed with pressure injuries, variance inflation factors (VIFs) were calculated for all independent variables, including physiologically related conditions such as diabetes mellitus, peripheral vascular disease, stroke and malnutrition. The maximum VIF was 3.8, indicating no evidence of problematic multicollinearity.
The general characteristics of hospitalised patients with pressure injuries are presented in Table 1. A total of 178,818 patients with pressure injuries were identified in 2017, 185,324 in 2018 and 180,501 in 2019. The mean age of the patients was 74.60 years in 2017, 75.05 years in 2018 and 75.48 years in 2019, and most patients were between 70 and 89 years of age. The mean length of hospital stay was 19.01 days in 2017, 21.82 days in 2018 and 18.91 days in 2019, with the longest average stay observed in 2018. Regarding pressure injury stage, Stage 3 pressure injuries were the most common, accounting for 74,922 cases (42.0%) in 2017, 77,959 cases (42.1%) in 2018 and 78,735 cases (42.6%) in 2019. Overall, the annual number of hospitalised patients with pressure injuries remained relatively stable during the study period, with a modest increase observed in 2018 (Table 1).
TABLE 1.
General characteristics of hospitalised patients with pressure injuries, 2017–2019 (n = 544,643).
| Characteristics | 2017 year (n = 178,818) | 2018 year (n = 185,324) | 2019 year (n = 180,501) |
|---|---|---|---|
| n (%) | |||
| Gender | |||
| Male | 84,544 (47.3) | 87,927 (47.5) | 83,766 (46.4) |
| Female | 94,274 (52.7) | 97,397 (52.5) | 96,735 (53.6) |
| Age (year) | |||
| 18–29 | 1233 (0.7) | 1168 (0.6) | 943 (0.5) |
| 30–49 | 8600 (4.8) | 8395 (0.5) | 7678 (4.3) |
| 50–69 | 40,259 (22.5) | 40,598 (21.9) | 38,962 (23.6) |
| 70–89 | 114,289 (63.9) | 118,737 (64.2) | 115,834 (62.4) |
| ≤ 90 | 14,437 (8.1) | 16,426 (12.8) | 17,084 (9.2) |
| M (SD) | 74.60 (13.40) | 75.05 (13.33) | 75.48 (13.12) |
| Number of days in the hospital | |||
| Mean (SD) | 19.01 (11.07) | 21.82 (12.78) | 18.91 (11.73) |
| Pressure injury stage | |||
| Stage I | 26,801 (15.0) | 19,540 (10.5) | 22,365 (12.4) |
| Stage II | 46,805 (26.2) | 56,144 (30.3) | 46,592 (25.8) |
| Stage III | 74,922 (42.0) | 77,959 (42.1) | 78,735 (42.6) |
| Stage IV | 30,290 (16.8) | 31,681 (17.1) | 32,809 (19.2) |
Table 2 presents the distribution of comorbidity profiles among hospitalised patients with pressure injuries. Hip disease, urinary incontinence, faecal incontinence, paralysis, diabetes mellitus, malnutrition, stroke, chronic obstructive pulmonary disease and peripheral vascular disease showed significant differences in patient distributions according to the presence or absence of each condition (all p < 0.05). A history of falls was identified in only 74 patients (0.2%); nevertheless, the distribution of patients according to fall history also differed significantly (p = 0.008) (Table 2).
TABLE 2.
Distribution of pressure injury patients according to comorbidity profiles (n = 544,643).
| Variables | n (%) | χ 2 | p |
|---|---|---|---|
| Alzheimer's disease | |||
| Yes | 542,694 (99.6) | 11.83 | 0.063 |
| No | 1949 (0.4) | ||
| Hip disease | |||
| Yes | 544,004 (99.9) | 61.81 | 0.004* |
| No | 649 (0.1) | ||
| Urinary incontinence | |||
| Yes | 541,135 (99.4) | 1955.85 | < 0.001* |
| No | 3518 (1.6) | ||
| Faecal incontinence | |||
| Yes | 544,064 (99.4) | 23.46 | 0.023* |
| No | 579 (0.6) | ||
| Paralysis | |||
| Yes | 399,693 (73.4) | 4249.44 | < 0.001* |
| No | 144,950 (26.6) | ||
| Diabetes mellitus | |||
| Yes | 317,976 (58.4) | 2684.79 | < 0.001* |
| No | 226,667 (41.6) | ||
| Malnutrition | |||
| Yes | 514,317 (94.4) | 2948.48 | < 0.001* |
| No | 30,266 (5.6) | ||
| Stroke | |||
| Yes | 395,774 (72.7) | 2872.15 | 0.003* |
| No | 148,869 (27.3) | ||
| Chronic obstructive pulmonary disease | |||
| Yes | 385,057 (70.7) | 4751.88 | < 0.001* |
| No | 159,586 (29.3) | ||
| Peripheral vascular | |||
| Yes | 520,371 (95.5) | 5795.29 | < 0.001* |
| No | 24,272 (0.5) | ||
| Fall experience | |||
| Yes | 74 (0.2) | 98.75 | 0.008* |
| No | 544,569 (99.8) |
Note: χ 2 = Chi‐square statistic from Rao‐Scott Chi‐square test (considering complex sample design).
p < 0.05.
Table 3 presents the distribution of patients with pressure injuries according to clinical department. Over the three‐year study period, the largest proportion of patients with pressure injuries was treated in the Department of Internal Medicine (n = 231,737, 42.55%), followed by the Department of Family Medicine (n = 79,468, 14.59%) and the Department of Orthopaedic Surgery (n = 75,091, 13.79%). The Departments of Rehabilitation Medicine and Neurology accounted for similar proportions of patients, comprising 33,706 (6.19%) and 31,108 (5.71%) patients, respectively. The Department of Neurosurgery accounted for the smallest proportion of patients with pressure injuries (n = 21,687, 3.98%) (Table 3).
TABLE 3.
Distribution of pressure injury patients according to clinical department.
| Variables | n (%) | Sequence |
|---|---|---|
| Medicine | 231,737 (42.55) | 1 |
| Family medicine | 79,468 (14.59) | 2 |
| Orthopaedics | 75,091 (13.79) | 3 |
| General surgery | 44,250 (8.12) | 4 |
| Rehabilitation medicine | 33,706 (6.19) | 5 |
| Neurology | 31,108 (5.71) | 6 |
| Urology & obstetrics and gynaecology | 27,596 (5.07) | 7 |
| Neurosurgery | 21,687 (3.98) | 8 |
Table 4 presents treatment patterns according to pressure injury classification among hospitalised patients with pressure injuries. Over the three‐year study period, the most common treatment category was the application of foam and hydrocolloid dressings among patients with Stage 3 or higher pressure injuries (n = 187,653, 32.8%). This was followed by inflammatory treatment among patients with Stage 2 pressure injuries (n = 145,445, 26.7%) and the application of film dressings among patients with Stage 1 pressure injuries (n = 139,091, 25.6%). In contrast, wet dressings (n = 1425, 0.8%), skin flap surgery (n = 97, 0.3%) and skin graft procedures (n = 72, 0.2%) were the least frequently used treatments and were performed primarily in patients with Stage 3 or higher pressure injuries.
TABLE 4.
Treatment modalities according to pressure injury stage.
| Variables | n (%) | Pressure ulcer stage |
|---|---|---|
| Foam, hydrocolloid dressing | 187,653 (32.8) | ≤ Stage III |
| Inflammatory treatment | 145,445 (26.7) | Stage II |
| Film dressing | 139,091 (25.6) | Stage I |
| Debridement inclusive wound suture | 38,147 (7.0) | Stage II |
| Simple suture | 13.951 (2.6) | Stage I |
| Alginate dressing | 11,515 (2.1) | ≤ Stage III |
| Negative‐pressure wound therapy | 7247 (1.9) | Stage II |
| Wet dressing | 1425 (0.8) | ≤ Stage III |
| Skin flap surgery | 97 (0.3) | ≤ Stage III |
| Skin graft | 72 (0.2) | ≤ Stage III |
Factors associated with advanced‐stage pressure injury classification (Stages 3–4) compared with mild‐stage pressure injury classification (Stages 1–2) among hospitalised patients with pressure injuries are presented in Table 5. Several demographic and clinical characteristics were significantly associated with advanced‐stage pressure injury classification.
TABLE 5.
Multivariable predictors of advanced‐stage pressure injury classification (stage 3–4 vs. stage 1–2).
| Variables | OR | 95% CI | p | |
|---|---|---|---|---|
| Lower | Upper | |||
| Gender (ref. female) | 1.25 | 1.22 | 1.30 | < 0.001* |
| Age (ref. every year increase) | 1.02 | 1.00 | 1.03 | < 0.001* |
| Number of days in the hospital (ref. every day increase) | 1.02 | 1.01 | 1.04 | < 0.001* |
| Alzheimer's disease (ref. no) | 0.93 | 0.89 | 0.97 | 0.001* |
| Hip disease (ref. no) | 1.91 | 1.27 | 1.99 | < 0.001* |
| Urinary incontinence (ref. no) | 3.32 | 2.61 | 3.38 | < 0.001* |
| Faecal incontinence (ref. no) | 1.23 | 1.13 | 1.34 | 0.002* |
| Paralysis (ref. no) | 1.88 | 1.84 | 1.89 | 0.001* |
| Diabetes mellitus (ref. no) | 1.92 | 1.88 | 1.99 | < 0.001* |
| Malnutrition (ref. no) | 2.76 | 2.71 | 2.80 | < 0.001* |
| Stroke (ref. no) | 1.68 | 1.63 | 1.72 | < 0.001* |
| Chronic obstructive pulmonary disease (ref. no) | 1.93 | 1.88 | 1.97 | < 0.001* |
| Peripheral vascular disease (ref. no) | 1.72 | 1.68 | 1.78 | < 0.001* |
| Fall experience (ref. no) | 0.48 | 0.46 | 0.50 | < 0.001* |
Note: Dependent variable = Pressure injury severity (0 = Stage 1 or 2, 1 = Stage 3 or 4); This analysis includes only patients diagnosed with pressure injuries.
Abbreviations: CI, confidence interval; OR, odds ratio; ref., reference.
p < 0.05.
Regarding demographic characteristics, male patients had higher odds of advanced‐stage pressure injury classification than female patients (OR = 1.25, 95% CI: 1.22–1.30, p < 0.001). For each one‐year increase in age, the odds of advanced‐stage pressure injury classification increased by 2% (OR = 1.02, 95% CI: 1.00–1.03, p < 0.001). Likewise, each additional day of hospitalisation was associated with a 2% increase in the odds of advanced‐stage pressure injury classification (OR = 1.02, 95% CI: 1.01–1.04, p < 0.001).
With respect to comorbid conditions, patients with hip disease had 1.91‐fold higher odds of advanced‐stage pressure injury classification than those without hip disease (OR = 1.91, 95% CI: 1.27–1.99, p < 0.001). Urinary incontinence showed the strongest association with advanced‐stage pressure injury classification, with affected patients having 3.32‐fold higher odds than those without urinary incontinence (OR = 3.32, 95% CI: 2.61–3.38, p < 0.001). Faecal incontinence and paralysis were also significantly associated with advanced‐stage pressure injury classification, with odds ratios of 1.23 (95% CI: 1.13–1.34, p = 0.002) and 1.88 (95% CI: 1.84–1.89, p = 0.001), respectively.
Malnutrition was associated with 2.76‐fold higher odds of advanced‐stage pressure injury classification (OR = 2.76, 95% CI: 2.71–2.80, p < 0.001). Other comorbid conditions that were significantly associated with advanced‐stage pressure injury classification included diabetes mellitus (OR = 1.92, 95% CI: 1.88–1.99, p < 0.001), chronic obstructive pulmonary disease (OR = 1.93, 95% CI: 1.88–1.97, p < 0.001), peripheral vascular disease (OR = 1.72, 95% CI: 1.68–1.78, p < 0.001) and stroke (OR = 1.68, 95% CI: 1.63–1.72, p < 0.001). In contrast, Alzheimer's disease (OR = 0.93, 95% CI: 0.89–0.97, p = 0.001) and a history of falls (OR = 0.48, 95% CI: 0.46–0.50, p < 0.001) were associated with lower odds of advanced‐stage pressure injury classification (Table 5).
4. Discussion
Among hospitalised patients already diagnosed with pressure injuries, the annual number of cases remained relatively stable during the study period and the mean age of patients was approximately 75 years. Most patients were between 70 and 89 years of age, consistent with previous studies reporting that pressure injuries are particularly common among older adults (Dallow et al. 2024; Han et al. 2019). Although the present study did not include a comparison group without pressure injuries, the predominance of older adults and relatively long hospital stays are consistent with previous reports (Hyun 2021; Rodziewicz et al. 2021). These findings may reflect age‐related changes in skin structure and function, including impaired tissue perfusion, reduced skin integrity and diminished regenerative capacity, all of which increase vulnerability to tissue damage and complicate pressure injury management (Park et al. 2019). Therefore, early identification and appropriate management of pressure injuries in older hospitalised patients are essential.
The findings also highlight the importance of adequate nursing resources and timely interventions for patients already diagnosed with pressure injuries, particularly those at risk of advanced‐stage pressure injury classification. Appropriate nurse staffing may facilitate comprehensive skin assessment, monitoring and preventive care, thereby helping to limit advanced‐stage pressure injury classification and improve patient outcomes (Gaspar et al. 2022). Furthermore, active communication among healthcare professionals is essential to ensure accurate staging, appropriate documentation and individualised management planning. Previous studies have shown that emotional exhaustion and burnout among nurses may adversely affect the quality and safety of pressure injury care (Gómez‐Urquiza et al. 2020; Han et al. 2019; Petrelli et al. 2020).
Among hospitalised patients with pressure injuries, urinary incontinence was the most common comorbidity and showed the strongest association with advanced‐stage pressure injury classification. This finding is consistent with previous studies reporting a higher prevalence of severe pressure injuries among incontinent patients (Eylem and Semine 2023; Kayser et al. 2019). Prolonged exposure to urine and faeces may cause chemical irritation, inflammation and skin breakdown, thereby compromising tissue integrity and complicating the management of existing pressure injuries (Health Insurance Review and Assessment Service 2021; Park et al. 2019). Because incontinence‐associated dermatitis may resemble pressure injuries and lead to misclassification, careful assessment and appropriate moisture management are essential. Developing unit‐specific nursing protocols may facilitate early identification and management of patients at risk of advanced‐stage pressure injury classification (Eylem and Semine 2023).
Foam and hydrocolloid dressings were the most frequently used treatments, followed by anti‐inflammatory treatment and film dressings. Previous studies have suggested that foam and hydrocolloid dressings are commonly used because of their ability to absorb exudate and maintain a moist wound environment that supports wound management (Mervis and Phillips 2019; Park et al. 2019; Yu et al. 2021). These findings underscore the importance of selecting dressings according to wound characteristics, including wound size, depth and exudate amount. Regular skin assessment and maintenance of skin hygiene are also important components of pressure injury management and may help reduce complications related to wound contamination and infection (Hernández‐Vásquez et al. 2022; Mervis and Phillips 2019).
This study identified several demographic and clinical characteristics associated with advanced‐stage pressure injury classification among hospitalised patients with pressure injuries. Male sex, older age and longer hospital stay were significantly associated with higher odds of advanced‐stage pressure injury classification. In addition, urinary incontinence, malnutrition, chronic obstructive pulmonary disease, diabetes mellitus, paralysis and peripheral vascular disease were significantly associated with advanced‐stage pressure injury classification.
The strong association between urinary incontinence and advanced‐stage pressure injury classification is consistent with findings from national inpatient claims studies reporting a greater prevalence of severe tissue damage among incontinent patients (HIRA 2021). Similarly, the high odds ratio observed for malnutrition highlights the potential importance of nutritional status in pressure injury management. Adequate protein intake is essential for cellular regeneration, connective tissue synthesis and collagen production, all of which are critical for tissue repair and wound healing (Posthauer et al. 2018). However, because the present study was based on retrospective claims data, these findings should be interpreted as associations rather than causal relationships.
Diabetes mellitus was also significantly associated with advanced‐stage pressure injury classification. Previous studies have suggested that diabetes may impair sensory perception, neurological responses and microvascular circulation, thereby adversely affecting tissue repair and wound healing (Dong et al. 2021; Van Netten et al. 2020). Although causality cannot be established, these findings suggest that patients with diabetes and other chronic comorbidities may require closer monitoring and more intensive management following pressure injury diagnosis. Timely assessment and evidence‐based management strategies may help limit advanced‐stage pressure injury classification and improve patient outcomes (Park 2023).
Interestingly, patients with a history of falls had lower odds of advanced‐stage pressure injury classification. However, because the present study was based on retrospective claims data and included only patients with diagnosed pressure injuries, the mechanisms underlying this association remain unclear. The relatively small number of patients with a fall history and the possibility of residual confounding warrant cautious interpretation. Further longitudinal studies are needed to clarify the relationship between fall history and pressure injury classification (Baek and Park 2023; Zeb et al. 2019).
4.1. Limitations
This study identified that male sex, older age and comorbidities such as urinary incontinence and malnutrition were significantly associated with advanced‐stage pressure injury classification (Stages 3–4) among hospitalised patients already diagnosed with pressure injuries. These findings may help identify patients who are more likely to present with advanced‐stage pressure injuries and inform targeted assessment and management strategies for high‐risk groups.
However, several limitations should be considered when interpreting these findings. First, because HIRA claims data are administrative records generated primarily for reimbursement purposes, coding errors, undercoding and reimbursement‐driven coding practices may have resulted in misclassification of diagnoses and pressure injury stages. In addition, the database lacked important clinical variables, including Braden Scale scores, nutritional biomarkers, functional status, mobility and detailed wound characteristics, and residual confounding by unmeasured factors cannot be excluded. Second, because this study was based on retrospective, cross‐sectional claims data and compared patients with advanced‐stage pressure injury classification (Stages 3–4) and mild‐stage pressure injury classification (Stages 1–2), temporal relationships between patient characteristics and pressure injury classification could not be established. Consequently, reverse causation cannot be ruled out, and some variables, such as length of hospital stay, may represent either antecedent characteristics associated with advanced‐stage pressure injury classification or consequences of advanced‐stage pressure injury classification. Therefore, the observed associations should be interpreted as correlational rather than causal, and within‐patient longitudinal changes in pressure injury classification could not be evaluated.
Future prospective longitudinal studies incorporating direct clinical assessments are needed to validate these findings and improve the precision of pressure injury assessment and management in clinical practice.
4.2. Implications for Practice and Future Research
The findings of this study highlight the need for evidence‐based clinical protocols and practical guidelines for the early identification and management of hospitalised patients with pressure injuries who are at increased risk of advanced‐stage pressure injury classification. In particular, targeted assessment and monitoring should be prioritised for patients with characteristics associated with advanced‐stage pressure injury classification, including older age, male sex, urinary incontinence, malnutrition, diabetes mellitus, chronic obstructive pulmonary disease, paralysis and peripheral vascular disease. Such approaches may facilitate timely interventions and improve patient safety and the quality of nursing care.
The present findings also support the development of individualised nursing interventions and multidisciplinary management strategies for patients with pressure injuries and complex comorbid conditions. Future studies should prospectively examine longitudinal changes in pressure injury classification and recurrence and evaluate whether targeted interventions for high‐risk patients can reduce advanced‐stage pressure injury classification. In addition, disease‐specific pressure injury management guidelines and intervention programmes should be developed and validated through prospective and experimental studies. Ultimately, these efforts may contribute to the development of evidence‐based national policies and clinical strategies for improving pressure injury management and severity outcomes among hospitalised patients.
5. Conclusion
This study demonstrated that male sex, older age and longer hospital stay were significantly associated with advanced‐stage pressure injury classification (Stages 3–4) among hospitalised patients already diagnosed with pressure injuries. Among patients with pressure injuries, urinary incontinence showed the strongest association with advanced‐stage pressure injury classification, followed by malnutrition, chronic obstructive pulmonary disease, diabetes mellitus, hip disease, paralysis, peripheral vascular disease, stroke and faecal incontinence.
These findings suggest that patients with these demographic and clinical characteristics may require closer assessment and more intensive management because they are more likely to present with advanced‐stage pressure injury classification. Accordingly, evidence‐based and disease‐specific nursing protocols, supported by adequate staffing and practical clinical guidelines, should be implemented across clinical settings. In practice, nurses may improve the quality of care by prioritising these severity‐associated factors during the assessment and management of patients with pressure injuries.
Furthermore, the factors identified in this study provide an empirical basis for the development of AI‐driven predictive algorithms and mobile health applications designed to estimate the likelihood of advanced‐stage pressure injury classification among patients with existing pressure injuries. Incorporating these factors into digital health tools may facilitate the early identification of patients at greater risk of advanced‐stage pressure injury classification and support timely, targeted interventions. Ultimately, the systematic application of these findings may contribute to improving pressure injury management, patient safety and clinical outcomes among hospitalised patients with pressure injuries.
Author Contributions
Study design: M.G., Y.S.C., S.S. Data collection: M.G., Y.S.C., S.S. Data analysis: M.G., S.S. Study supervision: S.S. Manuscript writing: M.G., Y.S.C., S.S. Critical revisions for important intellectual content: M.G., S.S. All authors are in agreement with the content of the manuscript.
Funding
The authors have nothing to report.
Ethics Statement
In ethical considerations, the Institutional Review Board of Korea University in South Korea approved this study (IRB No. 2020‐0266).
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgements
The authors gratefully acknowledge the Health Insurance Review and Assessment Service for providing the statistical data (project number M20200403435).
Data Availability Statement
No new data were created or analysed in this study. Data sharing is not applicable to this article.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
No new data were created or analysed in this study. Data sharing is not applicable to this article.