Introduction

Venous Leg Ulcers (VLUs) are a significant health problem worldwide. VLUs are a chronic skin condition of the lower limbs, often affecting the elderly and those with chronic health illnesses [1, 2]. VLUs affect approximately 1–3% of adults globally [2–4]. Furthermore, these wounds tend to be severe; recent evidence suggests that almost 20% of wounds present in aged community samples are VLUs [5]. The prevalence of VLU increases with age, doubling among those aged over 65 years [4, 6] The typical VLU patient tends to be female, over 65 years old, has a high risk of cardiovascular events, and has obesity [7]. VLU patients often face ongoing health and quality of life problems [6, 8] partially because the treatment itself requires substantial self-management, leading to significant intrapersonal and interpersonal burdens [3, 6, 9].

For decades, the best practice recommendation for those with an active VLU has been consistent-the use of compression therapy and physical activity [10, 11] Research suggests that the use of below-knee multi-component compression is efficacious [12–14] Compression therapy promotes VLU healing by reducing the hydrostatic pressure in lower limbs, enhancing venous return [10] and preventing venous stasis [15] Consistent compression therapy is recommended to prevent VLU recurrence [12–14] While other lifestyle changes are also commonly recommended, such as adequate nutrition, leg elevation and particularly physical activity [10, 16, 17] the most consistent evidence base has been the recommendation to patients to consistently use and self-apply compression garments.

In recent years, there has been renewed interest in the idea of patient health literacy (HL) in how patients adhere to treatments like compression therapy and physical activity. Patient HL is defined as “the ability to obtain, process, and understand basic health information”. There is some overlap between HL and health knowledge with knowledge of health, health care and systems identified as an element of HL in some definitions. HL provides a toolkit beyond health knowledge alone that can enable patients to apply their knowledge for successful self-management. It is likely that there is a relationship between patients’ knowledge of when and how to use information and the knowledge that they hold. HL is not monolithic; in fact, it is better to see health literacy as health literacies [18] as literacy is related both to the content and the context in which a patient must act. Therefore, here we detail a theoretical distinction between general HL often assessed through population-level surveys [19] and specific HL which deals with health skills and knowledge specific to the condition or disease [20]. “General” HL, as described here, relates to a conceptualisation of HL as a bundle of higher level skills required in order to acquire, understand, and apply health knowledge [18] This is further split in most studies along three key domains: functional literacy (encompassing skills in reading and writing to function), communicative/interactive literacy (extracting/applying new information to changes in circumstances) and critical literacy (advanced skills to critique and use information to control situations and life events when needed; [21]. General HL scales are often used to assess a patient’s general capabilities in accessing and navigating health services (e.g., where do you go for medical advice), often for the purpose of directing health policy at a population scale [18, 21]. However, because health literacy often requires more specific skills that do not neatly fit into functional, communicative, or critical domains, focusing on a specific health literacy that is activated by specific illness contexts may add to our understanding of the impact of HL on health conditions. Therefore, specific HL scales assess individual capabilities in dealing with a specific condition by examining specific skills and confidence that require integration of communicative, functional, and critical literacy in a specific way. For example, specific HL scales exist for diabetes by extending the HL scales to be more specific toward diabetes management skills, such as capacity to understand insulin management [20, 22].

Both general and VLU-specific HL may affect VLU outcomes through affecting patient’s ability to adopt health behaviours. Improvements in general and specific HL may improve patient knowledge and understanding of the benefits of adhering to VLU self-management recommendations [23–25], and support patients to adopt healthy behaviours in line with an agreed management plan. For example, when choosing compression hosiery, patients may rely on HL to critique the options based on their analysis of comfort [26] compared with achieving maximum therapeutic benefit [27]. Furthermore, HL may enhance their compression application skills due to improved understanding of the manufacturer’s instructions [14, 28]. Finally, improved HL may influence patient understanding that lifelong compression hosiery is recommended to prevent VLU recurrence [29].

Recent research has reported that people vulnerable to VLUs, those with VLUs, and those with other comorbidities tend to have concurrent unmet HL needs [30]. For example, although the 2015 European HL survey showed that respondents received an average score of 33.8/50 (demonstrating “sufficient” HL), the majority (58%+) of people aged over 66 years had limited HL, compared to less than half of the general population [19]. A possible reason is internet usage. Though internet usage is proportional to increased HL [31], current research consistently reports that older adults prefer to learn from their health care professionals [29], as opposed to independent learning through the use of the internet [32]. Qualitative research has shown that VLU patients often discuss the volume of information and skills that are needed for self-management upon VLU development as a significant burden, as VLU self-management can be complex [23] and demanding [24]. The education needs of VLU patients are not well understood [25] contributing to unmet HL needs. In general, limited HL in adults is associated with reduced adherence to treatment and health recommendations, poorer health outcomes and increased cost of medical treatment [33], especially amongst older adults [34]. Furthermore, checking on patient understanding is not a routine practice for health care professionals [5], although this was recommended in at least one set of international guidelines on VLU care [11].

Research objectives and present study

The aim of this scoping review was to scope the research examining the level of HL in VLU patients, how this level may link to self-management behaviours/knowledge (particularly physical activity and compression adherence), and VLU healing generally. Given that HL in VLU patients appears less extensively researched than other factors in VLU healing, we opted to conduct a scoping review. This review type was a flexible method for identifying and discussing information useful for answering our research questions, and allowing a holistic presentation of the available literature on this topic [42]. Our primary question was:

1. 1) What levels of HL (both general and specific) have been reported in adults with active or past VLUs across outpatient, home care, community, and inpatient care?

Our secondary research questions were as follows:

1. 2) Is there any relationship (correlational or experimental) between HL and VLU patient adherence to compression therapy, health knowledge, and physical activity?
2. 3) Is there any relationship between HL and VLU patient healing outcomes?

Methods

The approach for this scoping review was adapted from the PRISMA [43] guidelines for scoping reviews. We conducted the review in accordance with the PRISMA Extended for Scoping Reviews (PRISMA-ScR) [14] (Table 1). Methods were developed based on guidelines developed by Levac et al. [43] using the six framework stages in the published protocol [44].

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Table 1. Included studies.

https://doi.org/10.1371/journal.pone.0279368.t001

Help in formulating and executing this search was provided by the host university’s Library services at [redacted] University, [city, location]. This search strategy was registered in the published protocol [44]. No ethics approval was required as we used data from publicly available platforms with no risk of identification of participants.

Using COVIDENCE and EndNote, one author (AB) ran multiple searches through academic search engines (EBSCOhost, PubMed, Open Grey) and public search engines (e.g., Google Scholar) to search through the targeted databases of MEDLINE, EMBASE, the Cochrane Library, PsycInfo and Health, Open Grey, and Google Scholar. This search strategy sought to find papers to answer the three research questions. The search was limited to January 2000 to August 2020, with the most recent search conducted February 2021. The literature search was developed using a combination of medical search headings and free text words. The keywords and search string relevant to Medline via Ovid can be found in S1 Appendix. The full search was conducted using Boolean operators and proximity operators, including wildcards, AND, OR, parentheses, quotations, and more as per the database used. All papers went through a quality assessment. This assessment of the included studies was independently conducted by AB and VT, and any differences in the quality assessment were resolved through a consensus meeting and discussion We used the Critical Appraisal Skills Program (CASP) Checklist for RCTs (see [45]) for the included RCTs by Clarke Moloney et al [46] and Protz et al [47] the National Institutes of Health (NIH) Quality Assessment Tool of controlled intervention studies [48] for the included non-randomised controlled intervention by Gonzalez [49]; the NIH Quality Assessment Tool for observational cohort and cross-sectional studies see [48] for a cross-sectional study by Finlayson et al; and NIH Quality Assessment Tool for before-after (pre-post) studies with no control group for the pre- and post- educational intervention study by Gonzalez [50]. All CASP assessments can be found in S1 File.

Authors also had to make a judgement on whether or not HL was specific or general, as most papers did not clarify this distinction; all authors worked together to reach a consensus on this categorisation.

Results

Search results

The literature search retrieved 660 citations; 29 duplicates were excluded resulting in 629 titles (Fig 1). Overall, 23 were considered eligible for potential inclusion. Following full text assessment, we further excluded 18 studies, leaving five remaining. Fig 1 describes this process, and Table 1 details the findings. Due to the low number and study heterogeneity, no synthesis was attempted. The inconsistent way in which HL was described by authors led to some overlap between HL and prior health knowledge. Some studies detailed skills as part of health knowledge, and therefore these studies were retained. Therefore, this assessment of quality of evidence was left to a discussion between authors instead, and represented through a table (Table 1).

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Fig 1. PRISMA flow diagram.

https://doi.org/10.1371/journal.pone.0279368.g001

Discussion

This review was aimed to scope the literature that examined HL (both broad and disease specific) in people with VLUs, and how HL might link to self-management (particularly compression adherence and physical activity) knowledge and healing outcomes. Limited conclusions could be reached from these studies, as there were few that met the criteria overall. The included studies suggested that VLU specific HL was low, and disease-specific HL interventions may have some impact on specific HL and wound healing. Therefore, it is possible that HL does have some link with compression utilisation and wound healing, but the evidence is limited.

The included study that examined HL in VLU patients suggests that specific HL is low [51]. Overall, most studies suggested that VLU-specific HL was far below what would be needed in order to manage one’s condition. There is no research using a standardized general HL tool in VLU patients, like the well validated HLS-EU-Q16 [52]. However, by focusing on specific HL on a debilitating condition that consumes a large amount of time and effort by patients [53], arguably this may be superior than a general intervention that may not add VLU specific skills in some environments. For example, in Australia, contacting one’s general practitioner and following their recommended treatments may have utility for heart disease, but asking about VLUs would most likely lead to incorrect treatment advice from General Practitioners (GPs) as GP knowledge on VLU treatment is low [7, 54]. Furthermore, even if GPs did offer correct information, there is a gap between patient and GP motivations in VLU management, meaning this gap likely also affects attending to specific HL advice [55]. Therefore, assessing VLU specific HL may be a superior assessment.

There were no identified research studies that examined the correlation between HL and the predictors of adherence to physical activity, and VLU wound healing. Only one correlational study showed VLU specific HL was associated with greater self-reported compression rates [51]. Intervention-based research suggest there may be some utility in improving HL to improve patient activities in compression and therefore, wound healing. Most notably, the two American studies by Gonzales [49, 50] provided the strongest link, finding that improving VLU specific HL improved knowledge and the likelihood of recurrence. While VLU healing was not affected, this was likely due to the smaller sample size (i.e., smaller or medium effect sizes undetectable in smaller samples) or the delayed effect of HL improvement on VLU improvement.

The lack of research on physical activity and HL in VLUs was surprising, but may be due to the significant controversy in whether or not physical activity, in addition to compression, has any effect [17]. Although there is strong theoretical evidence for physical activity in improving VLU healing [56], the link may be weaker or more distal than other factors [17], and thus fewer studies may seek to examine this factor relative to more direct links.

Overall, the research into HL and VLUs is too limited to make any assertions on the state of HL in VLU patients, and how HL may relate to compression, healing, or physical activity. Recent health belief research on patients with other types of ulcers with similar risk profiles indicated that prior assumptions and knowledge were integral in adherence to health directives [57]. The little evidence that exists on HL and VLUs seems to have similar implications.

Conclusions

The results of this review suggest that there is a lack of high-quality research on the links between HL and VLU patients’ compression utilisation and VLU healing. Limited research suggests that there is a deficit of HL in VLU patients. While the effects of HL have received more attention in recent years in other conditions, such as diabetic foot ulcers, surprisingly little research has been conducted on the role of HL in VLU management. We, therefore, highlight the need for a quality prospective study that employ validated HL tools to assess HL in patients with VLUs.

Supporting information

Acknowledgments

Monash Library

Catelyn Richards (research assistant)