Abstract
Leg ulcers are hard to heal. Infection causes delayed healing, negatively impacting patients’ quality of life, the healthcare system, and society. Early recognition of patients at high risk of infection is essential to prevent complications and reduce negative impacts. However, at present, factors associated with infection in this population are not yet clearly understood.
The study aimed to identify factors that were significantly associated with infection in chronic leg ulcers. A sample of 561 patients with chronic leg ulcers, who were previously recruited at outpatient clinics and community settings within Australia between 2008 and 2015, were selected for the current analysis. The prevalence of infection in the sample at study recruitment was 7.8%.
A multivariate logistic regression model was used to identify factors associated with infection. The study identified 7 factors that were significantly independently associated with infection, including depression, chronic pulmonary disease, anti‐coagulant use, calf ankle circumference ratio < 1.3, ulcer area ≥ 10 cm2, slough in the wound bed tissue, and ulcers with heavy exudate.
These findings could assist clinicians in the early recognition of patients at risk of infection and individualise treatment for these patients, thereby promoting wound healing.
Keywords: infection, leg ulcer, risk factor
1. INTRODUCTION
Worldwide, chronic leg ulcers impact almost 3% of people aged 60 years and above and more than 5% of those aged above 80 years.1 One‐third of the leg ulcers do not heal after 6 months.2 Infection prolongs wound healing and increases complications and mortality in patients with leg ulcers,3 resulting in a negative impact on the patients’ quality of life and increased financial burden on the healthcare system and society.4 The prevalence of infection is very high in chronic wounds, ranging from 22%5 to 27%.6
Identifying patients at a high risk of infection is important, in order to minimise their risk for infection and prevent further complications, reducing the negative impact of infection.4, 7 Importantly, while there are a number of suggested risk factors that may influence the development of wound infections,4, 8, 9, 10, 11, 12, 13 the majority of studies focused on general or surgical wounds.14, 15 Few studies investigated the risk factors for infection in chronic wounds.16, 17, 18, 19, 20, 21 Thus, a thorough examination of the factors that may be associated with infection in chronic leg ulcers is clearly needed.
This study was guided by the framework suggested by World Union of Wound Healing Societies (WUWHS) in the “Principles of best practice: Wound infection in clinical practice. An international consensus” document4 and aimed to identify factors that were significantly associated with clinically diagnosed infection in patients with chronic leg ulcers.
2. METHODS
2.1. Design
This was a cross‐sectional study using combined data from 4 longitudinal prospective studies. The data were collected from 2008 to 2015.
2.2. Sample
Patients were recruited from outpatient clinics and community settings in Australia. These studies aimed to: (1) explore wound exudate biochemical characteristics from chronic wounds (data were collected between 2011 and 2014), (2) validate a risk assessment tool for delayed healing of venous leg ulcers (data were collected between 2012 and 201522), (3) determine effective care pathways for evidence‐based care for patients with chronic wounds (data were collected between 2009 and 2010),23, 24 and (4) evaluate healing outcomes of patients with chronic wounds (data were collected between 2008 and 2015). Participants were recruited if they: had a chronic wound for a duration longer than 4 weeks (either venous leg ulcers, arterial leg ulcers, mixed leg ulcers, or other types of chronic leg ulcers); were a community‐living patient; and were able to attend outpatient clinic, community‐based wound clinics, or receive community home nursing services. Patients were excluded if they were unable to understand English.
The cases in previous studies were included in this current study if de‐identified data were from participants who were 18 years old or above, had at least 1 leg ulcer below the leg, which has been present for 4 weeks or more, had an ulcer diagnosed as primarily either venous, arterial, or mixed. Participants were excluded if they: had been diagnosed with cognitive impairment, had a malignancy present in the leg ulcer, or had diabetic foot ulcers. For those who had 2 or more ulcers in the same previous study, 1 ulcer was included and the others were randomly excluded. A total of 561 patients who fitted this inclusion and exclusion criteria were included in this study (Figure 1).
Figure 1.
Flowchart of potential and included cases from previous studies
2.3. Data collection
Data were prospectively collected from the time of recruitment until 24 weeks either weekly or every 2 weeks. Data collected included the participants’ demographic information, medical histories (including comorbidities, medications, and vascular history), and medical assessments including wound and psychological assessments. Wound infection status was also clinically assessed and documented, including whether wounds were considered clinically infected or not, as diagnosed by the clinicians in charge. In studies 1 and 4, the clinical diagnosis of wound infection was made by either a nurse practitioner in wound management, vascular physicians, or registered nurses with experience in wound care. In studies 2 and 3, this diagnosis was made by either nurse practitioners in wound management, medical practitioners specialising in wound care or registered nurses with experience in wound care. The diagnosis was based on the clinicians’ experience and current national and international consensus documents at the time the studies were done.4, 7, 25
Socio‐demographic information included: gender, age, source of income, marital status, possession of a health care card, and living arrangements (eg, living alone, with family): suburb or residence. Patients’ medical histories included comorbid conditions, current medications, vascular history, smoking status, and use of walking aids.
Patients were assessed on admission to the included studies for the level of pain, ankle brachial pressure index, calf and ankle circumference, ulcer and surrounding tissue characteristics, and ulcer infection status.
Data on pain were measured using the Numerical Pain Rating Scale.26 Participants were asked to indicate their level of pain on a Numerical Pain Rating Scale that ranged from 1 to 10.
Ankle Brachial Pressure Index (ABPI) was calculated by dividing the systolic blood pressure measured at the ankle with the systolic blood pressure measured at the arm.27 Calf and ankle circumferences (CACs) were measured at the maximal point of the calf for calf circumference and the ankle circumference was measured at the minimal point of the ankle. CAC ratio was calculated by dividing ankle circumference by the calf circumference.28
Ulcer characteristics included location, ulcer areas in square centimetres, tissue type, and type and level of exudate. The Pressure Ulcer Scale for Healing (PUSH) tool was used to assess the ulcer severity and healing by calculating a score from ulcer area categories, amount of exudate, and type of ulcer tissue.29 The total PUSH score ranged from 0 to 17. A decrease in the total PUSH score can be seen as an indicator for positive wound healing.24 The PUSH tool has been validated for use with monitoring healing and severity of chronic wounds.30
A clinical diagnosis of infection was recorded in all the contributing studies, and 1 study documented a detailed range of clinical signs of infection by the clinician who was in charge of care.
2.4. Ethical considerations
This study complied with the ethical rules of the Declaration of Helsinki and was approved by the Queensland University of Technology Ethics Committee, Queensland, Australia (ID#: 1500001146).
2.5. Statistics
The IBM SPSS 23.0 software (IBM Corp., Armonk, New York) was used for analysis. Descriptive analyses were undertaken for all variables. Frequencies were run on categorical variables along with means, SDs, medians, and ranges as appropriate for continuous variables. χ 2 tests, t tests or Mann‐Whitney U tests were carried out to determine any bivariate relationships between possible risk factors and clinical diagnosis of a leg ulcer infection. P values of less than .05 were used as the cut‐off for statistical significance. A Fisher exact test was used if the expected value in any of the cells of any of the variables was less than 5.31 The findings from the bivariate analyses were then used as a guide to undertake a binary logistic regression analysis. All variables that were determined to be significantly associated with clinical infection (P < .05) or close to significance (P < .2)32, 33, 34, 35 were evaluated first for multi‐collinearity. If variables were regarded as highly correlated (r ≥ 0.5), the decision about which variables were put into the logistic regression model was based on the research questions and factors that could be easily and simply used by clinicians in their daily practice. All the variables meeting the criteria were then entered into a binary logistic regression model to explore and identify any independent factors significantly associated with clinically diagnosed infection in patients with chronic leg ulcers while controlling for potential confounders.
3. RESULTS
3.1. Sample characteristics
The combined dataset consisted of 561 ulcers from 561 patients, including 388 (74%) venous leg ulcers, 133 mixed leg ulcers (20%), and 40 arterial leg ulcers (6%). The participants’ mean (SD) age was 71.16 (14.40) years, in which the youngest was aged 19 years and the oldest was aged 98 years. Two‐thirds of the patients were aged 65 years or older (n = 400); 281 patients (50.1%) were male and 280 patients (49.9%) were female (Table 1).
Table 1.
Characteristics of the study sample
| Characteristics | N (%) |
|---|---|
| Demographic | |
| Gender | |
| Male | 281 (50.10%) |
| Female | 280 (49.90%) |
| Age, mean ± SD | 71.16 (14.41) |
| Healthcare card | 252 (61.90%) |
| Care for others | 51 (9.10%) |
| Live alone | 185 (33.30%) |
| Walking aids | 205 (36.70%) |
| Smoking | 55 (10.00%) |
| Pain score, mean ± SD | 3.289 (2.77) |
| Co‐morbidities | |
| Diabetes | 102 (18.20%) |
| Osteoarthritis | 213 (38.00%) |
| Depression | 56 (10.00%) |
| Heart disease | 232 (41.40%) |
| Hypertension | 342 (61.00%) |
| Rheumatoid arthritis | 39 (7.00%) |
| Peripheral vascular disease | 129 (23.00%) |
| Chronic pulmonary disease | 98 (17.50%) |
| Gout | 41 (7.30%) |
| Sleep apnoea | 34 (6.10%) |
| ≥3 comorbidities | 307 (54.70%) |
| Medications | |
| Anti‐coagulants | 262 (46.70%) |
| Anti‐hypertensives | 325 (57.90%) |
| Diuretics | 165 (29.40%) |
| Analgesics | 300 (53.50%) |
| Respiratory medications | 74 (13.20%) |
| Ventolin | 40 (7.90%) |
| Anti‐depressants | 91 (16.20%) |
| Non‐steroidal anti‐inflammatory drugs | 86 (16.60%) |
| Statin medications | 139 (24.90%) |
| Allopurinol | 27 (4.90%) |
| Diabetic medications | 75 (13.40%) |
| ≥4 medications | 239 (42.60%) |
| Ulcer characteristics | |
| PUSH score (range 0‐17), mean ± SD | 9.29 (3.40) |
| Ulcer duration ≥ 24 weeks | 220 (40.40%) |
| Ulcer area ≥ 10 cm2 | 103 (18.60%) |
| Slough tissue | 185 (33.30%) |
| Heavy exudate | 177 (31.90%) |
Of the 561 chronic leg ulcers, 44 ulcers were clinically diagnosed as infected, which resulted in the prevalence of ulcer infections at the time of recruitment at 7.84%. This prevalence of infection was calculated from the previous studies, with 8.49% infected ulcers (18/212) from study 1, 9.75% (8/82) from study 2, 5.26% (8/152) from study 3, and 8.69% (10/115) from study 4.
The majority of the patients (61.9%) were on pension or unemployment benefits. Thirty‐three percent of the patients reported living alone while 9% had to care for others. Almost 37% of the participants used a walking aid to mobilise. More than half of the patients were either diagnosed with hypertension or with ≥3 other comorbid conditions. More than 50% of the participants reported taking either anti‐hypertensive medications or analgesics, followed by anti‐coagulants taken by 47%. Polypharmacy was also examined, defined as taking 4 or more medications, with almost 43% of the participants reported taking more than 4 medications at recruitment (Table 1).
Approximately 44% of the participants reported having the ulcer for more than 24 weeks and 21% had the ulcer area being equal or greater than 10 cm2. The PUSH total score (ranging from 0 to 17) was also calculated with a mean of 9.5 ± 3.32 points. One‐third of the ulcers presented with either heavy exudate or slough tissue (Table 1).
3.2. Bivariate tests
Eleven variables were found to be significantly associated with clinically diagnosed infection (P < .05). These variables included the patient's age ≥ 65 years, chronic pulmonary disease (CPD), anti‐coagulants, respiratory medications, calf ankle circumference (CAC) ratio < 1.3, PUSH score, ulcer area ≥ 10 cm2, ulcers with heavy exudate, and ulcer with slough in the wound bed (Table 2). Five other variables had a P‐value of <.2 in bivariate tests, including lived alone, smoking, depression, anti‐depressants, and site of the ulcer (Table 2).
Table 2.
Bivariate relationship between demographic and health factors and clinically diagnosed leg ulcer infection
| Factor | Non‐infected | Infected | χ2 | P |
|---|---|---|---|---|
| N = 517 (%) | N = 44 (%) | |||
| ≥ 65 years old | 376 (72.70%) | 24 (54.40%) | 6.55 | .010 |
| Live alone | 166 (32.50%) | 19 (43.20%) | 2.09 | .149 |
| Smoking | 48 (9.50%) | 7 (15.90%) | .186a | |
| CPD | 84 (16.20%) | 14 (31.80%) | 6.82 | .009 |
| Depression | 48 (9.30%) | 8 (18.20%) | 3.57 | .059 |
| Anti‐depressants | 87 (16.80%) | 4 (9.10%) | 1.79 | .181 |
| Anti‐coagulants | 249 (48.20%) | 13 (29.50%) | 5.65 | .017 |
| Respiratory drugs | 63 (12.20%) | 11 (25.00%) | 5.82 | .016 |
| Site of the ulcer | ||||
| Left leg | 299 (58.2%) | 31 (70.5%) | 2.53 | .112 |
| Right leg | 215 (41.8%) | 13 (29.5%) | ||
| Ulcer area ≥ 10 cm2 | 84 (16.40%) | 19 (43.20%) | 19.17 | <.001 |
| Slough tissue | 162 (31.70%) | 23 (52.30%) | 7.71 | .005 |
| Heavy exudate | 153 (29.90%) | 24 (54.50%) | 11.29 | .001 |
| CAC ratio < 1.3 | 21 (4.30%) | 7 (17.10%) | .003a |
| Factor | Mean (SD) | Mean (SD) | t | P |
|---|---|---|---|---|
| Age in years | 71.53 (14.37) | 66.89 (14.36) | 2.06 | .040 |
| PUSH score (range 0‐17) | 9.11 (3.35) | 11.42 (3.40) | −4.33 | <.001 |
| Pain score (range 0‐10) | 3.22 (2.76) | 4.20 (2.77) | −2.03 | .043 |
Abbreviations: CAC, calf ankle circumference; CPD, chronic pulmonary disease; PUSH, pressure ulcer scale for healing.
Fisher's exact test was used due to 25% of the cells have expected count < 5.
3.3. Logistic regression
All 12 variables that were significantly associated with clinically diagnosed infection (P < .05) in bivariate tests and 5 variables that had P < .2 were first evaluated for multi‐collinearity. As there were 2 measures of age (age in years and age ≥ 65 years), PUSH score was correlated with ulcer, depression correlated with anti‐depressants, and chronic pulmonary disease correlated with respiratory drugs. Thus, 12 independent variables remained and then entered in a binary logistic regression model. These variables included: age, lived alone, smoker, depression, CPD, taking anti‐coagulants, CAC ratio < 1.3, ulcer area ≥ 10 cm2, pain score, site of ulcer, slough tissue, and heavy exudate.
The initial model containing all the 12 factors was statistically significant, χ 2 = 42.980 (12, N = 456), P < .001, indicating that the model was able to distinguish between participants who were clinically diagnosed with ulcer infection, and those who were not. The model as a whole explained 22.2% (Nagelkerke R 2 equivalent) of the variance in the outcome, infection. A parsimonious model was then formed via backward steps in which variables were taken out from the model, 1 at a time if they were not significantly related to the outcome, and the removal of the variable made no or little change to the goodness of fit tests. Significance tests, odds ratios, and 95% confidence intervals were examined for independent variables to determine the degree of association each variable had with clinical infection. The Z residual was used to check for outliers, if there were any cases with a very high level of Z residual of ≥5, it was excluded from the sample size. One outlier was excluded from the sample size.
Overall, the final model (as shown in Table 3) contained 7 independent variables and was statistically significant, χ 2 = 46.295 (7, N = 519), P < .001. The model as a whole explained 20.4% (Nagelkerke R 2 equivalent) of the variance in prevalence of clinically diagnosed infection. After controlling for all the variables, 7 independent variables made a unique statistically significant contribution to the model including depression, CPD, anti‐coagulant use, CAC ratio < 1.3, ulcer area ≥ 10 cm2, slough tissue, and heavy exudate.
Table 3.
Factors independently associated with clinical diagnosed leg ulcer infection (n = 519 leg ulcers, 40 clinically diagnosed infected leg ulcers at baseline)a
| β‐coefficient | P | Odds ratio | 95% CI | |
|---|---|---|---|---|
| Chronic pulmonary disease | 0.82 | .036 | 2.27 | 1.05‐4.87 |
| Depression | 1.02 | .035 | 2.78 | 1.08‐7.19 |
| Anti‐coagulants | −0.77 | .045 | 0.47 | 0.22‐0.98 |
| Calf ankle ratio < 1.3 | 1.62 | .001 | 5.04 | 1.86‐13.69 |
| Ulcer area ≥ 10 cm2 | 0.84 | .032 | 2.31 | 1.08‐5.11 |
| Slough tissue | 0.91 | .013 | 2.49 | 1.21‐5.11 |
| Heavy exudate | 0.98 | .010 | 2.65 | 1.27‐5.55 |
There were missing data in some variables thus only 519 left in the analysis.
Having a calf ankle circumference ratio of <1.3 was associated with odds of being 5 times more likely to have an infection, after controlling for all other factors in the model (95%CI = 1.86‐13.69, P = .001). Being diagnosed with depression was found to be significantly associated with a higher risk of infection with an odds ratio of 2.27, 95%CI = 1.08‐7.19, P = .035. Ulcers with heavy exudate were almost 3 times more likely than those with small or moderate exudate to have infection, holding other factors constant (Odds ratio = 2.65, 95%CI = 1.27‐5.55, P = .010).
4. DISCUSSION
Infection is an important cause for delayed healing and hospitalisation of patients with chronic leg ulcers. The identification of the prevalence of infection and factors associated with infection is essential to enhance early recognition of infection in chronic leg ulcers.
In this study, the prevalence of infection in the sample of 561 cases was 7.84%, which was much smaller compared to other studies using the same clinical criteria to diagnose infected leg ulcers. In a cross‐sectional study of 77 chronic leg ulcers from 75 participants, De Souza found 27% of the ulcers were infected.6 Similarly, Rondas et al in 2015 found 22% (16/72 chronic wounds) were found infected.5 This discrepancy could be explained by the following reasons. First, in the 2014 study, the sample (77 cases) was much smaller than the current study sample (561 cases). Second, in the 2015 study, the majority of the chronic wounds were pressure ulcers (46%) and post‐surgical wounds (9.5%), while venous leg ulcers were only 3.6% and arterial ulcers 1.6%.5 Importantly, this prevalence was still significant generating a number of infected ulcers in the whole population.
This is the first known study to assess the relationships between a large number of risk factors (including physical, psychological, social factors, and ulcer characteristics) and infection in chronic leg ulcers, and confirmed the significant relationships between 7 factors and clinical diagnosis of leg ulcer infection (P < .05). Of these, depression; chronic pulmonary disease; taking anti‐coagulants; calf‐ankle circumference ratio < 1.3; ulcer area ≥ 10 cm2; ulcers with slough tissue; and ulcers with heavy exudate are newly identified factors that contribute to the comprehensive nature and complexity of the literature. This study also provides evidence for the association between an existing risk factor and a large ulcer area, with leg ulcer infection.4, 21
4.1. Framework for risk factors associated with infection in chronic leg ulcers
These results of the current study confirm the theoretical framework of the World Union Wound Healing Society (WUWHS), which can be used when assessing for risk of infection in chronic leg ulcers. The WUWHS suggested theoretically that the risk of chronic leg ulcer infection will increase if patients have any factors that debilitate them, impair their immune response or reduce tissue perfusion, and some leg ulcer characteristics may increase the risk of infection.4 The findings reported here provide clear evidence for these suggestions which have not been previously reported (See Figure 2).
Figure 2.
Framework for risk factors associated with infection in chronic leg ulcers
4.2. Comorbidities
This is the first study to find that depression was significantly related to leg ulcer infection, with participants diagnosed with depression being 3 times more likely to have infection than those without depression. Depression has been shown to be an important factor influencing a range of infections in acute settings,14 as it influences patients’ immune functions.8, 9
Chronic pulmonary disease (CPD) was previously identified as a risk factor for infection in postoperative patients15 and suggested to be associated with infection in chronic leg ulcers.7 In this study, CPD was independently significantly associated with infection in chronic leg ulcers as those who had CPD were 2 times more likely to have an ulcer infection (P = .036). CPD causes reduced tissue perfusion or poor oxygenation of the tissue in the ulcer area,4 however, the exact relationship between CPD and infections in chronic leg ulcers has not been previously reported. This important finding can be a potential contributor for the development of a predictive assessment tool for infection in chronic leg ulcers.
Although rheumatoid arthritis36, 37, 38 and peripheral vascular disease13 were believed to increase the risk of wound infections, the current study found no association between rheumatoid arthritis or peripheral vascular disease and infection in chronic leg ulcers. This result is similar to findings reported by Adam (2011) in a retrospective case‐control study of 48 patients with diabetic foot ulcer.10
4.3. Medications
Anti‐coagulant drugs were identified in this study as significantly associated with less risk of leg ulcer infection. This is an important finding suggesting a need for further research.
Medications, such as corticosteroids, were suggested in the literature to be associated with infections, including increased risk of skin and soft tissue infection37 and increased risk of infection in patients with surgical wounds.12 However, this study found no association between taking steroids and leg ulcer infections, which is consistent with the findings from Ruyssen‐Witrand and Fautrel,38 whose systematic review found that the incidence of infection in patients who were taking a dose of 10 mg corticosteroids was similar to those who were not taking it.38
4.4. Ulcer and lower limb factors
Importantly, the previously unreported relationships between infection and ulcers with slough tissue and/or heavy exudate were also confirmed in the current study. Ulcer area ≥ 10 cm2, ulcers with slough tissue, and ulcers with heavy exudate were significantly related to infection in the current study. This study confirms results from previous research between wound area and delayed healing39 or non‐healing in chronic leg ulcers.22 In a 189‐patient prospective study, ulcer surface of >20 cm2 has been found to be an indicator for slow healing in chronic leg ulcers.28 The current study found that 80% of ulcers had an ulcer area of <10 cm2; therefore, the cut point ulcer surface of ≥10 cm2 was used. A larger wound has also been reported to be associated with infection in chronic wounds21 or suggested to be significantly associated with infection in chronic leg ulcers.4, 40 However, there was little clarity about how wound area statistically related to infection in chronic leg ulcers. This study provides a significant relationship between ulcer area and infection, which can assist clinicians in identifying patients at high risk of infection.
In relation to lower limb factors, the current study found patients who had a calf‐ankle circumference ratio of <1.3 were also significantly related to infection. The relationship between calf muscle pump and wound healing has been shown in the literature.41 A calf ankle circumference ratio of <1.3 indicates an impairment of the calf muscle pump,28 which has been found to be significantly related to failure to heal chronic venous leg ulcers using compression treatment. As infection is one of the important factors delaying healing, results from this study confirm the significant association between calf muscle pump dysfunction and infection in patients with chronic leg ulcers. Thus, this is an important result that strengthens evidence in the literature.
4.5. Age and infection
In spite of the fact that age was reported to be significantly associated with skin and soft tissue infections, the current study did not confirm this relationship. For instance, a study of 619 patients by Talan et al18 found that age of ≥65 years was significantly related to skin and soft tissue infection. Age was also found to be associated with surgical wound infection in a prospective study of 7602 patients.15 Although the current study found patients’ age was significantly associated with infection in a bivariate test, when controlling other factors in a multivariable logistic regression, age did not remain significantly related to leg ulcer infection. This finding is consistent with the findings from a longitudinal study of 1666 patients with diabetics, where the authors found no association between age of ≥70 years and foot infections.16
4.6. Strengths and limitations
The current study provides clinical evidence from multiple site studies with a large sample size. The study used variables that can be easily measured by clinicians in practice. Therefore, the findings are relevant and applicable to a variety of wound care settings.
This study had some limitations. As the data used were combined from previous studies, information was not collected from all the contributing studies. Small numbers in some variables, such as surrounding tissue and malnutrition, limited the findings related to these variables. Also, only few variables in the psychosocial category were investigated.
5. CONCLUSION
In conclusion, in the current study of 561 participants with either chronic venous leg ulcers, arterial leg ulcers or mixed leg ulcers, the prevalence of infection was 7.84%. Seven factors were significantly associated with clinically diagnosed leg ulcer infection. A number of new risk factors were identified (chronic pulmonary disease, depression, calf ankle ratio < 1.3, slough tissue, and heavy exudate level), and the known risk factor, larger ulcer area, was confirmed (ulcer area ≥ 10 cm2); thus providing a contribution to the under‐studied area of infection in chronic leg ulcers. These potential risk factors for leg ulcer infections, however, should be further evaluated.
ACKNOWLEDGEMENTS
The authors acknowledge the staff and patients from participating study sites at Queensland University of Technology's Wound Healing Community Outreach Service, Royal Brisbane & Women's Hospital, Royal District Nursing Services (Victoria), and Blue Care Community Nursing services for their time and generous commitment to the contributing studies in this research.
The first author acknowledges the support of Queensland University of Technology as this study has been undertaken in partial fulfilment of a Doctor of Philosophy. The first author also acknowledges the Wound Innovation Management Cooperative Research Centre and the Australian Government's Cooperative Research Centre Programme for their provision of financial support throughout the first author's PhD. The authors confirmed that there is no conflict of interest known between the funding body and the findings from this study.
Conflict of interest
The authors declare no potential conflicts of interest.
Bui UT, Edwards H, Finlayson K. Identifying risk factors associated with infection in patients with chronic leg ulcers. Int Wound J. 2018;15:283–290. 10.1111/iwj.12867
Funding information Queensland University of Technology scholarship, Grant/Award number: Research TRaining Program Stipend; Wound Management Innovation CRC Ltd, Grant/Award number: Wound Management Innovation CRC Top‐Up Scholarship
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