A Prospective Study of Pressure Injury Healing Rate and Time and Influencing Factors in an Acute Care Setting : Advances in Skin & Wound Care

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A Prospective Study of Pressure Injury Healing Rate and Time and Influencing Factors in an Acute Care Setting

Seo, YoungMin PhD, RN; Oh, HyunSoo PhD, RN; Na, YoungSun BSN, RN; Kim, MiJin MSN, RN; Seo, WhaSook PhD, RN

Author Information
Advances in Skin & Wound Care: December 2022 - Volume 35 - Issue 12 - p 1-9
doi: 10.1097/01.ASW.0000892488.90282.a4
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Abstract

INTRODUCTION

The incidence of pressure injuries (PIs) in adults varies from 0% to 12% in acute care settings and from 1.9% to 59% in long-term care settings.1,2 In Korea, 2.7% of patients in general hospitals and 8.2% of patients in long-term care facilities develop at least one PI during their hospitalization.3

It may take weeks to months or sometimes even years for PIs to heal.4,5 Patients often experience delayed hospital discharge due to a PI or may be discharged with an unhealed PI.6 The healing time of PIs depends on various factors, including PI stage and type of care setting.7 In general, PI healing times tend to be longer in long-term care facilities than in acute care settings.8,9 Delayed healing increases morbidity and cost and is often frustrating for patients and caregivers.10

Because PI healing is a complex, multifactorial process, identifying factors that influence PI healing is important for determining key management factors that facilitate the healing process. A substantial number of studies have been conducted to identify these factors and associated demographic characteristics, as well as disease-, wound-, and treatment-related factors.11–15 However, study findings vary considerably, and these inconsistencies make it difficult to apply findings in clinical practice. The majority of studies on PI healing have focused on long-term care residents or on specific treatments, interventions, or PI stages.8,11,16 Further, because those studies differed in terms of outcome variables measured, PI stages, and measurement timings,8,9,17 it is not possible to draw reliable conclusions about factors that influence PI healing.

Pressure injuries increase hospital stays and treatment and care costs and thus exert financial burdens on patients, families, and healthcare systems.18 Further, PIs may result in serious complications, such as gangrene, systemic inflammatory syndrome, sepsis, or even death.19 Prevention is the primary objective of PI care, but if a PI develops, prompt healing is needed to minimize related complications. In this context, knowledge of the factors that influence PI healing is important to plan effective PI management.

Study Objective

The researchers aimed to determine PI healing rates and times in patients who had developed at least one PI during their stay in an acute care hospital. In addition, they developed and tested a comprehensive model to identify significant influencing factors of PI healing rate and time.

Theoretical Model

The authors devised a theoretical model based on empirical evidence; it includes previously reported factors of PI healing. The most well-known demographic factor is age.11,15 In addition, the following factors have been reported to affect PI healing: the presence of comorbidity,12,18,20 reduced activities of daily living (ADLs),8,11,13 poor nutrition status,8,21 and incontinence.8,11,22 Physiologically, hemoglobin and serum albumin and creatinine levels also are associated with PI healing.12,13,20,22,23 However, the most important factors that directly influence PI healing are wound-related factors: PI site,8,18 size,8,9,11,13,22 and stage.18,24 In addition, wound treatments, such as the type of wound dressing,8,14 removal of necrotic tissue (debridement),8 use of pressure redistribution devices,9,14 and administration of protein,9,14 can have direct and/or indirect effects through their influences on physical or physiologic factors.

Of the aforementioned factors, 17 were reported in two or more studies and were included in the hypothetical model: demographic (age, sex); physiologic (serum total protein, albumin, creatinine, glucose, and hemoglobin levels); physical (incontinence, ADLs, and nutrition status); and disease- (diagnosis, number of comorbidities, and cardiovascular comorbidity), wound-, (PI stage and size at first detection, and Pressure Ulcer Scale for Healing [PUSH] score), and treatment-related (IV nutrition supply and albumin infusion) factors (Figure 1).

F1
Figure 1.:
HYPOTHETICAL MODEL OF FACTORS INFLUENCING PI HEALINGAbbreviations: ADLs, activities of daily living; PI, pressure injury; PUSH, Pressure Ulcer Scale for Healing.

METHODS

Study Design and Participants

A prospective cohort research design was used. The study participants were 77 inpatients who had developed at least one PI during their stay in a university hospital. Only patients who satisfied the following criteria were recruited: (1) an age of 19 years or older; (2) development of a PI after hospital admission; and (3) the provision of consent after being informed of the study purposes and procedures. Patients with a PI before hospitalization were excluded.

According to the power analysis conducted using G*Power (University of Düsseldorf), the minimum sample size required was 81 (α = .05, effect size = 0.24, power (1 − β) = 0.80, and number of predictors = 11). Effect size was calculated to be 0.24 based on the study by Park and Kim.9 Initially, 87 patients were recruited to account for an expected loss of 5% to 10% because of missing data or erratic responses. Three patients were excluded because of failure to meet the inclusion criteria, four for discharge or death before data collection was completed, and three because more than 30% of the data were missing. Some patients developed more than one PI. Because these PIs were at different stages and located at different sites, the researchers counted them separately.

Measurements

The collected patient and clinical factors were demographic (age, sex), disease-related (diagnosis and comorbidity), physiologic (serum total protein, albumin, and creatinine, blood glucose, and hemoglobin levels), physical (incontinence), and treatment-related (IV nutrition supply and albumin infusion). For physical factors, ADLs and nutrition status were assessed using the Korean-modified Barthel Index (K-MBI) and the Malnutrition Universal Screening Tool (MUST), respectively.

The MBI provides a measure of ADLs and thus of degree of physical independence.25 The K-MBI was translated into Korean and is a 5-point, 10-item (feeding, personal hygiene, bathing, dressing, transfers, bladder control, bowel control, stair climbing, and walking) scale.26 The highest possible score is 100, with higher scores indicating greater independence. The construct validity, reliability (Cronbach α = .94), and discriminative index of the K-MBI were confirmed.27

In the present study, the nutrition indices used were serum total protein and albumin levels and MUST score. Munoz et al28 determined that serum proteins are insufficient in terms of diagnostic performance because they are influenced by nonnutritional factors such as inflammation, renal function, hydration, and others. Therefore, the MUST was also used to evaluate nutrition status. The MUST is a five-step malnutrition screening tool29 that includes scores on three variables: body mass index, weight loss effect (unintentional weight loss during the previous 3-6 months), and acute disease effect (no nutrition intake for >5 days). Each parameter is rated as 0, 1, or 2, and the highest possible score is 6 (greatest risk of malnutrition). The criterion validity and interrater reliability of this tool were verified.30

Pressure injury stages were determined based on the definitions provided by the National Pressure Injury Advisory Panel, European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury:1 stages 1 through 4, unstageable, and deep tissue injury (DTI). Pressure injury healing was assessed using the PUSH, developed by the National Pressure Injury Advisory Panel.31 This tool measures three parameters that are considered indicative of healing: wound size, exudate amount, and tissue type. The predictive validity and interrater reliability have been verified.32–34 The PI healing time (in days) was assessed using time required for complete healing, as indicated by a PUSH score of zero.

Data Collection Procedure

All data were collected between May 2015 and August 2018 by three research assistants who were wound care nurses; they were instructed beforehand regarding the study purpose and data collection processes used. The wound care nurses were certified wound care specialists and responsible for taking care of any patients with PIs in the hospital where data were collected. To assess interrater agreement, the three wound care nurses independently determined PI stages in 10 randomly selected patients prior to major data collection. Intraclass correlation coefficient was 0.90 to 1.00.

Primary data collection was conducted within 48 hours of PI detection and included demographic (age, sex), disease-related (diagnosis, number of comorbidities, and cardiovascular comorbidities), physical (K-MBI and MUST scores and incontinence), physiologic (serum total protein, albumin, and creatinine, blood glucose, and hemoglobin levels), wound-related (site, stage, and size of PI and PUSH score), and treatment-related (IV nutrition supply and albumin infusion) factors (Figure 2). After primary data collection, physiologic, wound-related, and treatment-related factors were then measured every 7 days until complete healing, discharge, or death. Repeated serum total protein, albumin, creatinine, blood glucose, and hemoglobin measurements and PUSH scores were averaged.

F2
Figure 2.:
DATA COLLECTION PROCESSAbbreviations: ADLs, activities of daily living; K-MBI, Korean-Modified Barthel Index; MUST, Malnutrition Universal Screening Tool; PI, pressure injury; PUSH, Pressure Ulcer Scale for Healing.

Data Analysis

Statistical analysis was performed using SPSS 23.0 (IBM Corp). Demographic, disease-, wound-, and treatment-related characteristics were subjected to descriptive analysis. The significance of differences in healing rates or times between PI stages was determined using a χ2 test or t test. Factors influencing PI healing rate were identified by Cox regression analysis (Cox proportional hazard analysis) and factors associated with PI healing time were determined by multiple regression analysis.

Ethical Considerations

Data collection was performed after obtaining approval from the human research committee of the authors’ university (150413-1A), the directors of relevant departments, and the president of the university hospital where data were collected. All study participants were informed beforehand about the study purpose and procedures and assured that personal information would remain confidential, data would be published as means and ranges, and that they had the right to withdraw from the study at any point without prejudice. Written informed consent was obtained from all 77 study participants.

RESULTS

The number of study participants was 77, and the total number of PIs (cases) was 91. The mean participant age was 65.22 (SD, 17.28; range, 19–96) years; 40 (51.9%) were men, and 37 (48.1%) were women. The majority of study participants were admitted to internal medicine or surgical wards. Although a few ICU patients were included at the beginning of data collection, they all transferred to general wards when the acute phase of the disease passed. Sixty participants (77.8%) had incontinence (Table 1).

Table 1. - CHARACTERISTICS OF STUDY PARTICIPANTS
Variable n (%) Mean ± SD
Age, y (n = 77) 65.22 ± 17.28
 <65 32 (41.6)
 ≥65 45 (58.4)
Sex (n = 77)
 Male 40 (51.9)
 Female 37 (48.1)
No. of comorbidities (n = 77) 1.61 ± 1.27
 <2 37 (48.1)
 ≥2 40 (51.9)
Cardiovascular comorbidity (n = 77)
 No 34 (44.2)
 Yes 43 (55.8)
Diabetes mellitus (n = 77)
 No 53 (68.8)
 Yes 24 (31.2)
Incontinence (n = 75)
 No 15 (19.5)
 Yes 60 (77.9)
Activities of daily livinga (n = 77) 14.53 ± 23.81
 0 41 (53.2)
 1-46 27 (35.1)
 47-100 9 (11.7)
Malnutrition Universal Screening Tool score (n = 77)
 Low 42 (54.5)
 Medium/high 35 (45.5)
Pressure injury sites (n = 91)
 Lower extremities 8 (8.8)
 Trunk (torso) 83 (91.2)
Pressure injury stage at first detection (n = 91)
 Stage 2 38 (41.8)
 Unstageable/deep tissue injury 53 (58.2)
Pressure Ulcer Scale for Healing score (n = 91) 10.81 ± 3.03
 ≤8 23 (25.3)
 >8 68 (74.7)
IV nutrition supply (n = 77)
 No 32 (41.6)
 Yes 45 (58.4)
Albumin infusion (n = 77)
 No 38 (49.4)
 Yes 39 (50.6)
Mean serum albumin, mg/dL (n = 73) 2.92 ± 0.52
 ≤3.0 41 (53.2)
 >3.0 32 (41.6)
Mean serum glucose, mg/dL (n = 73) 116.91 ± 60.71
 ≤100 30 (39.0)
 >100 43 (55.8)
Mean serum creatinine, mg/dL (n = 73) 0.98 ± 0.95
 ≤1.2 58 (75.3)
 >1.2 15 (19.5)
Mean hemoglobin, g/dL (n = 74) 10.05 ± 1.24
 ≤10.0 39 (50.6)
 >10.0 35 (45.5)
aKorean version of Modified Barthel Index score.

Patient comorbidities were classified based on organ system. Of the 77 study participants, 40 (51.9%) had two or more comorbidities. The most common comorbidities were cardiovascular (n = 43 [55.8%]; hypertension, hyperlipidemia, coronary arterial disease, or congestive heart failure) and endocrine diseases (n = 24 [31.2%]; diabetes mellitus or thyroid diseases). In addition, a small number of patients had central nervous system (brain infarction or hemorrhage, or Parkinson disease; n = 15 [19.5%]), musculoskeletal (spinal stenosis, femoral fracture, or osteoarthritis; n = 8 [10.4%], or psychiatric disorders (dementia or depression; n = 7 [9.1%]). Accordingly, comorbidity-associated analysis was mostly based on cardiovascular and endocrine diseases.

In terms of ADLs, 41 participants (53.2%) had a K-MBI score of 0 (complete dependency), 27 (35.1%) scored between 1 and 46, and 9 (11.7%) scored between 47 and 100. Regarding nutrition, 42 participants (54.5%) had a low risk of malnutrition, and 35 (45.5%) had a medium/high risk. Of the 91 PI cases, 83 PIs (91.2%) were located on the trunk (back or pelvis), and 8 (8.8%) were located on a lower limb (Table 1). There were 38 (41.8%) stage 2 PIs and 53 (58.2%) unstageable PIs/DTIs. No stage 3 or 4 PIs were observed. The mean PUSH score of the 91 PI cases was 10.81 (SD, 3.03); PUSH scores were ≤8 in 23 cases (25.3%) and >8 in 68 cases (74.7%).

For PI treatment, IV nutrition (amino acid-containing or lipid-containing solutions) was administered to 45 of the 77 patients (58.4%). The majority of the study participants were fed through either an oral or an enteral tube. Some patients received additional nutrition support through parenteral routes. Thirty-nine participants (50.6%) received albumin infusion. Overall mean serum albumin level was 2.92 (SD, 0.52) mg/dL, and 41 participants (53.2%) had a serum albumin level ≤3.0 mg/dL. Overall mean blood glucose level was 116.91 (SD, 60.71) mg/dL, and 43 participants (55.8%) had a blood glucose level of >100 mg/dL. Mean serum creatinine level was 0.98 (SD, 0.95), and 15 participants (19.5%) had a serum creatinine level >1.2 mg/dL. Mean hemoglobin level was 10.05 (SD, 1.24) g/dL (Table 1).

PI Healing Rate and Time

Of the 91 PI cases, 54 (59.3%) healed. Overall, 27 of the 38 stage 2 PIs (71.1%) and 27 of the 53 unstageable PIs/DTIs (50.9%) healed; this difference in healing rates between stage 2 and unstageable PIs/DTIs was significant (χ2 = 3.71, P = .043). In terms of PI healing times, mean healing time for all 54 healed cases was 17.63 (SD, 20.28) days. However, the mean healing times of stage 2 and unstageable PIs/DTIs were 12.26 (SD, 7.87) and 23.00 (SD, 26.78) days, respectively, and this difference in healing time between stage 2 and unstageable PIs/DTIs was also significant (t = −2.00, P = .045; Table 2).

Table 2. - PI HEALING RATE AND TIME
Category Descriptive Statistics, n (%) or Mean ± SD Significance Test,
χ 2 (P) or t(P)
Healing rate (n = 91)
 Incomplete healing 37 (40.7)
 Complete healing 54 (59.3)
Healing time, d (n = 54) 17.63 ± 20.28
PI healing rate according to stage
Stage 2 (n = 38) 3.71 (.043)a
 Incomplete healing 11 (28.9)
 Complete healing 27 (71.1)
Unstageable/DTI (n = 53)
 Incomplete healing 26 (49.1)
 Complete healing 27 (50.9)
PI healing time according to stage, d
Stage 2 (n = 27) 12.26 ± 7.87 −2.00 (.045)a
Unstageable/DTI (n = 27) 23.00 ± 26.78
Abbreviations: DTI, deep tissue injury; PI, pressure injury.
Note: All 91 PI cases were included in the analysis of healing rate; only the 54 PI cases with complete healing were included in the analysis of healing time.
aFisher exact test (one-tailed test).

Factors That Influenced PI Healing Rate

The researchers developed a hypothetical model of 17 potential factors associated with PI healing. Cox regression analysis showed that the model was significant (χ2 = 36.31, P = .010, Table 3); that is, the model contained more than one factor that significantly influenced PI healing rate. Detailed analysis showed that the number of comorbidities, cardiovascular comorbidity, incontinence, PI stage at first detection, IV nutrition supply, and mean serum creatinine level all significantly affected PI healing rate.

Table 3. - FACTORS THAT INFLUENCE PRESSURE INJURY HEALING RATE: COX REGRESSION ANALYSIS (n = 91)
Predictors Model, χ 2 (P) Exp(B) 90% CI of Exp(B) Wald (P) a
No. of comorbidities 36.31 (.010) 2.80 1.15-6.81 3.63 (.029)
Cardiovascular comorbidity 0.14 0.06-0.34 12.91 (<.001)
Incontinence 4.99 1.24-19.97 3.63 (.029)
Pressure injury at first detection 3.53 1.72-7.26 8.32 (.002)
IV nutrition supply 2.38 1.19-4.80 4.19 (.020)
Mean serum creatinine level 0.40 0.17-0.91 3.32 (.034)
Note: In the hypothetical model, 17 potential predictors were included: age; diagnosis; number of comorbidities; cardiovascular comorbidity; incontinence; activities of daily living (Korean-Modified Barthel Index score); nutrition status (Malnutrition Universal Screening Tool score); pressure injury stage and size at first detection; Pressure Ulcer Scale for Healing score; intravenous nutrition supply; albumin infusion; and serum total protein, albumin, creatinine, blood glucose, and hemoglobin levels.
aOne-tailed test.

Analysis showed the probability of healing was 2.80-fold greater for patients with one comorbidity than for those with two or more comorbidities (Exp[B] = 2.80, P = .029). Patients with a cardiovascular comorbidity had a 7.14-fold higher probability of healing than did patients without (Exp[B] = 0.14, 1/0.14 = 7.14, P < .001), whereas patients without incontinence had a 4.99-fold higher probability of healing than did those with incontinence (Exp[B] = 4.99, P = .029). In addition, patients with a stage 2 PI had a 3.53-fold greater probability of healing than did those with an unstageable PI/DTI (Exp[B] = 3.53, P = .002). The probability of healing was 2.38-fold higher for patients without an IV nutrition supply (Exp[B] = 2.38, P = .020) and 2.5-fold higher for patients with serum creatinine level >1.2 mg/dL versus those with a level ≤1.2 mg/dL (Exp[B] = 0.40, 1/0.40 = 2.5, P = .034; Table 3).

Factors That Influenced PI Healing Time

Multiple regression analysis indicated that three factors significantly influenced PI healing time: number of comorbidities (β = 0.40, t = 2.24, P = .030), cardiovascular comorbidity (β = 0.38, t = 2.20, P = .017), and PI stage at first detection (β = 0.22, t = 1.65, P = .050). The total variance explained by these three factors was 16% (adjusted R2 = 0.16, F = 2.14, P = .024; Table 4). Time to heal was longer for patients with more comorbidities, with cardiovascular comorbidity, or with an unstageable PI/DTI at first detection. Of the three factors, the number of comorbidities had the greatest impact on PI healing time, followed by cardiovascular comorbidity and PI stage at first detection.

Table 4. - FACTORS THAT INFLUENCE PRESSURE INJURY HEALING TIME: MULTIPLE REGRESSION ANALYSIS (n = 54)
Predictors Adjusted R 2 F (P) β t (P) a
No. of comorbidities .16 2.14 (.024) .40 2.24 (.030)
Cardiovascular comorbidity .38 2.20 (.017)
Pressure injury stage .22 1.65 (.050)
Note: In the hypothetical model, 17 potential predictors were included: age; diagnosis; number of comorbidities; cardiovascular comorbidity; incontinence; activities of daily living (Korean-Modified Barthel Index score); nutrition status (Malnutrition Universal Screening Tool score); pressure injury stage and size at first detection; Pressure Ulcer Scale for Healing score; intravenous nutrition supply; albumin infusion; and serum total protein, albumin, creatinine, blood glucose, and hemoglobin levels.
aOne-tailed test.

DISCUSSION

Pressure injuries result in high economic burden in healthcare because of prolonged hospitalizations and increased morbidity and mortality.10,18 To reduce the risk of inpatients developing PIs and improve care quality, the researchers developed PI prevention and management protocols to be used by all health professionals in the hospital where data were collected. The protocols emphasize that prevention is the best strategy for dealing with PIs, beginning with the early identification of at-risk patients based on appropriate risk assessments. Specific PI prevention strategies for at-risk patients include (1) regular skin assessments, (2) use of support surfaces (eg, air mattress, gel pad), (3) regular repositioning, (4) use of prophylactic dressings over bony prominences, and (5) adequate nutrition support.

Regarding PI treatment, when nurses detect the development of a PI, they should promptly report this information to both the physicians and the specialized wound care nurses who are responsible for taking care of patients with PIs. Designated PI-related duties of the wound care nurses include (1) wound assessment, (2) selection of treatment plans, (3) implementation of PI management intervention (cleansing wounds, selecting and applying appropriate dressings, changing dressing, removing necrotic tissue, and protecting surrounding skin), and (4) evaluation of PI healing.

In the present study, 54 of 91 PIs (59.3%) healed with a mean healing time of 17.63 days. In more detail, 71.1% of stage 2 PIs healed with a mean healing time of 12.26 days, and 50.9% of unstageable PIs/DTIs healed with a mean healing time of 23.00 days. Thus, the healing rate was higher, and time to healing was shorter for stage 2 PIs than for unstageable PIs/DTIs. According to the National Pressure Ulcer Advisory Panel, European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury Alliance,1 if a PI does not show signs of healing as expected within 2 weeks despite appropriate local wound care, the PI and care plan should be reevaluated. Similarly, the present finding indicating 12.26 days for mean healing times of stage 2 PI provides evidence supporting the international clinical practice guidelines. This finding may provide empirical evidence for 12 to 14 days as the time required before reevaluating a PI and the associated care plan.

Bolton and colleagues17 reported PI healing rates and times in long-term care facilities and hospitals; they found that 61% of stage 2 PIs healed with a mean healing time of 31 days, and 36% of stages 3 and 4 PIs healed with a mean healing time of 62 days. Bergstrom et al8 reported that 45.4% of stage 2 PIs healed with a median healing time of 46 days. According to Park and Kim,9 50% of stage 2 PIs healed within 15 days, and 78.9% healed within 30 days. Findings in the present study indicate relatively higher healing rates and shorter healing times for stage 2 PIs than were reported in other studies. These differences may have been caused by different types of care settings. The majority of other studies were conducted in long-term care facilities or nursing homes, whereas the present study was conducted in a tertiary-level acute care hospital. In acute care hospitals, at-risk patients are assessed routinely to detect PIs at an early stage, and systematic and prompt management is conducted when a PI is detected. In addition, acute care hospitals are more likely to actively use medical devices/products and supportive therapies, such as nutrition, hydration, and pain control. These are all beneficial in terms of increasing healing rates and shortening healing times. The high rate of healing observed in the present study was likely at least partly due to a specialized wound care nursing program at the hospital where the data were collected. Recently, an integrative literature review revealed a significant positive impact of wound care nurses’ practice on health outcomes such as incidence and healing rate and time of PIs.35 It seems that the active involvement of wound care nurses in PI management is necessary at long-term care centers, nursing homes, and community health facilities.

In the present study, the number of comorbidities, cardiovascular comorbidity, incontinence, PI stage at first detection, IV nutrition supply, and mean serum creatinine level all significantly influenced PI healing rates. Patients with one comorbidity tended to have a higher probability of healing than did those with two or more comorbidities, which concurs with previous findings.12,18 Comorbidities cause skin to be more vulnerable to ulceration and thus more prone to PI development and delayed wound healing.36

Research has shown that cardiovascular dysfunction negatively affects PI healing,16,37 probably due to reduced tissue perfusion, tissue ischemia, hypoxia, interrupted nutrition or oxygen supply, and metabolic waste accumulation.38 In the present study, however, patients with a cardiovascular comorbidity had a higher PI healing rate than those without. This discrepancy may have been caused by the inclusion of different types of cardiovascular comorbidities. That is, whereas other studies mainly focused on peripheral vascular diseases or congestive heart failure,12,18,20 the majority of patients in the present study had hypertension (n = 35 [81.4%]), and only two (4.7%) of the 43 patients with a cardiovascular comorbidity had peripheral vascular disease or congestive heart failure. In addition, most of the patients with hypertension took antihypertensive medication, such as vasodilators, which may increase peripheral tissue perfusion. Further studies are needed to clarify the impacts of specific types of cardiovascular disease on PI healing.

Proper management of urinary or bowel incontinence is essential to prevent PIs and improve healing. Contact with moisture from incontinence has consistently been reported to increase skin vulnerability to pressure-induced blood flow reduction and to negatively impact wound healing.24,39 Fecal incontinence is especially damaging because stool contains digestive enzymes and bacteria that damage skin and increase the risk of secondary infection.40 Therefore, it is essential that PI wounds and surrounding intact skin be kept clean and free of urine and feces by frequent inspection and cleaning.

It has previously been proposed that PI healing is negatively associated with PI stage at presentation.24 The findings of the present study also indicate that patients with a stage 2 PI had a 3.53-fold higher probability of healing than did those with an unstageable PI/DTI. Although true depth in cases of zunstageable PI/DTI cannot be determined until slough or eschar is removed to expose the wound base, exposure is almost certain to result in a stage 3 or 4 classification.1

Nutrition plays an important role in the prevention and healing of PIs. In the present study, the nutrition indices tested were serum total protein and albumin levels and MUST scores. One of the problems with diagnosing malnutrition is the lack of a unified definition or standard methods for screening and diagnosis.41 Serum protein markers were once the standard blood biomarkers for diagnosing nutrition status but are no longer recommended for the sensitive biomarkers of malnutrition because they are influenced by nonnutrition factors such as inflammation, renal function, hydration, and others.28 Nevertheless, because serum protein biomarkers are easy and relatively cheap to measure and can estimate the overall prognosis, they remain widely used for malnutrition diagnosis in clinical practice.42 Careful consideration of findings on serum proteins is needed. Because of the insufficiency of serum proteins in terms of diagnostic performance, the authors also used MUST scores to evaluate nutrition status in the present study. However, neither the serum proteins tested nor MUST scores significantly influenced PI healing rate. Further studies using diverse nutrition indices, such as food intake, a medical diagnosis of malnutrition, weight, body mass index, and nutrition assessment scales,43 are needed to determine the association between nutrition status and PI healing rate.

In the present study, albumin infusion did not significantly influence PI healing rate, whereas IV nutrition supply had a significant negative effect (the probability of healing was 2.38-fold higher for patients without an IV nutrition supply). Because patients with poor nutrition status are more likely to receive IV nutrition, these patients may be at greater risk of impairing wound healing. Overall, 55.6% of the patients on IV nutrition had medium or high levels of malnutrition, whereas 31.3% of patients without an IV nutrition supply had medium or higher levels of malnutrition in the present study.

The present study also showed that the probability of PI healing was 2.5-fold greater for patients with a serum creatinine level >1.2 mg/dL. Creatinine is a waste product formed during the normal breakdown of muscle cells. The increased blood creatinine levels may indicate an increased protein-rich diet or muscle mass and has been reported to be significantly associated with reduced mortality.44,45 Thongprayoon and colleagues46 reported high mortality rates in ICU patients with low serum creatinine levels on admission. However, researchers have also noted that high serum creatinine levels due to kidney dysfunction are associated with delayed wound healing.20,47 Further studies are needed to clarify the nature of associations between serum creatinine and PI healing rates.

In patients with completely healed PIs, healing time was significantly influenced by the number of comorbidities, the presence of a cardiovascular comorbidity, and PI stage at first detection. Thus, PI healing time was significantly longer in patients with more comorbidities, a cardiovascular comorbidity, or unstageable PIs/DTIs. Notably, patients with a cardiovascular comorbidity had better healing rates, but longer healing times than those without. Additional studies are required to delineate relationships between cardiovascular comorbidity and PI healing.

Study Limitations

This study has a number of limitations that warrant consideration. First, stages 3 and 4 PIs were not included; further studies are needed that adequately represent all PI stages. Second, the impacts of different cardiovascular comorbidities on PI healing could not be evaluated because the main cardiovascular comorbidity included in the present study was hypertension. Third, it is generally acknowledged that serum proteins are not sensitive biomarkers of malnutrition. Therefore, careful consideration of findings on serum proteins is needed. Further studies using diverse nutrition indices are needed to clarify the association between nutrition status and PI healing. Fourth, the study was conducted on patients with PIs at one university hospital; therefore, findings are limited in terms of generalizability. A large-scale, multicenter study should be undertaken to confirm findings regarding factors that influence PI healing rate and time.

CONCLUSIONS

Prevention is the key to managing PIs, but not all PIs can be prevented. When a PI has developed, it is important to promote the healing process and prevent further deterioration. Although much progress has been made in terms of establishing standardized protocols for PI care, PIs are often difficult to heal. Based on findings in the present study, the authors suggest focusing on key factors that significantly affect PI healing rate and time.

Unstageable PIs and DTIs were classified for the first time in 2007, and there is very limited empirical research on these two stages, making them an important area of additional study. Although there are no specific data, the authors have noticed that more cases of unstageable PIs or DTIs are being diagnosed than stage 3 or 4 in the hospital where data were collected. In this context, this prospective study on the healing rates and times of unstageable and deep tissue PI would doubtless expand understanding of PI healing. This information may also be used for patient and family counseling.

Older adults are more susceptible to PI development, and societal aging will lead to increased incidence. The financial costs of prolonged hospital stays due to PIs exert considerable burdens on patients and their families. To reduce hospital stays, PI-related complications, and mortality rates, evidence-based management strategies are needed, and the findings in the present study may contribute to the development of such strategies.

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Keywords:

comorbidities; healing rate; healing time; pressure injury; pressure injury stage; wound healing

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