Introduction

Diabetes mellitus 2 (DM) is one of the main causes of hospitalization in adults ¹. With the increase in life expectancy, older adults (OA) with DM are a population group that is growing in developing countries; such is the case of those belonging to the Latin American (LA) region ². Foot ulcers are among the major complications of DM, a complication that can lead OA to be more prone to mobility disability because of a non-traumatic lower limb amputation ³. DM is the cause of 70% of lower limb amputations, positioning it as one of the main causes of disability in the LA region ¹, which implies depending on other people for activities of daily living thereby losing independence.

Periodic feet evaluation for neuropathy signs detection, circulation disorders and skin alterations in people with DM is a basic principle of comprehensive care for preventing diabetic foot (DF) ⁴, in addition to good management of early symptoms or manifestations, which presupposes education, hygiene and foot and disease care (e.g. diet, exercise, adherence to treatment, glycemic control) ^5,6.

Therefore, a systematic review on health interventions can provide valuable information on activities applied or included and their results in OA with DM in order to guide an intervention program in this population. This is because systematic reviews found address population groups of 18 years of age and over and are not specific to OA ^7,8.

Therefore, a knowledge gap was detected regarding the best health interventions in OA to prevent DF. This becomes relevant for primary care nursing staff, considering that OA are a vulnerable group, with functional decline and limited access to health services. Consequently, OA have a higher risk of complications from DM, including DF, which can affect the OA’s life quality, mobility, economy, and family and social care. Therefore, the purpose of this review was to explore the characteristics of the most effective health interventions for the prevention of diabetic foot in OA with DM.

Methodology

Systematic review, structuring a clinical question with the PICO format: Population (P), Interventions (I), Control (C [referring to the group]), Outcome (O). Being structured as: P: OA with DM, I: Most effective health interventions [randomized controlled studies], C: Intervention and comparison group, O: Prevention of DF. It was developed based on the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) criteria ⁹.

The quality of the studies was evaluated with the risk of bias criterion with the 8.5b risk of bias tool described by the Cochrane manual, Spanish version ¹⁰. The quality criteria assessed were selection, performance, detection, attrition and notification biases. These in turn are rated as high, medium or low quality.

Types of articles reviewed: Because only one randomized controlled trial (RCT) was located, the review was extended to evaluation programs and/or quasi-experiments. The interventions were classified into simple and complex. Simple interventions were those focused only on education compared to usual care (what the person is used to). Complex interventions included a comprehensive care approach (other care alternatives, in addition to what the person is used to) or those that combine education and comprehensive care, compared with standard care.

Selection criteria: Full-text articles, in English or Spanish, regarding intervention on foot care or prevention of DF in OA with DM or at least with a mean age of 60 or more years were included. The year of publication was not restricted. Articles whose interventions were aimed at healing DF or active ulcers, amputations, or drug experimentation, systematic reviews, meta-analyses, and book chapters were excluded.

The search for interventions was carried out from August 2019 to January 2020 in the Pub Med, Scopus, Web of Sciences Core Collection (KCL-Korean Journal Database, Russian Science Citation Index, Scielo Citation Index) databases.

The search terms used in English were elder, aging, ageing, older, later life, type 2 diabetes, glucose intolerance, diabetic foot, diabetic feet, foot diseases, foot problem, foot disease, foot ulcer, diabetic foot ulcer, diabetic foot infection, prevent, foot care, foot monitoring, clinical trial, clinical trial phase I, II, III and IV, controlled clinical trial, multicenter stud, randomized controlled trial, early termination of clinical trials, double-blind method, randomized, randomized, trial, trials, single, double, doubled, triple, tripled, treble, trebled, blind, mask, “4 arm”, “four arm”, evaluation studies, program evaluation, validation studies, pre, post, pretest, posttest, program, evaluat, effectiveness, intervention, noncontrolled studies, noncontrolled clinical trial, nonrandomized controlled trial, non-randomized controlled studies, quasi experiments, quasiexperiments, non-randomized, non-randomised.

The Boolean operators AND and OR were used to perform all possible combinations, increase specificity and reduce search sensitivity. The End Note^TM bibliographic manager was used to merge retrieved titles, remove duplicates, and screen titles and abstracts. The selection was carried out in three stages: in the first, the title and abstract were reviewed, during the second, the reading and analysis of full text, and in the third, the evaluation of quality of the selected studies. Once the database search strategies were established, 408 articles were retrieved, in addition to seven that were previously available, which gave a total of 415. The principal investigator extracted the studies according to the eligibility criteria for in-depth review, using the files for critical reading (FLC 2.0) of clinical trials. When evaluating the articles by title and abstract, those that did not meet the inclusion criteria were removed. Subsequently, twenty-nine articles were reviewed in full text to obtain the final sample of nine articles. From the nine articles selected, the following was obtained: characteristics of the study (randomized controlled study [RCS], evaluation program or quasi-experiment), characteristics of the population (age and time of DM), intervention period (time, number of sessions), and type of intervention (delivery to the intervention group and delivery to the control group), (Figure 1). The results were divided into primary and secondary results. As primary outcome, the following was considered: existing or non-existing development of skills and/or foot care (washing, moisturizing, monitoring). The secondary outcome comprised the percentage that included the lack of formation of foot ulcers at the end of the intervention and during the follow-up.

Source: own-development.

Figure 1 Flowchart for the selection of PRISMA articles, (2019-2020) 

Results

From the nine articles selected 66.7% of the studies were quasi-experiments without a control group ^13-18, 22.2% RCTs ^11,12, and 11.1% evaluation programs ¹⁹. 88.9% reported complex interventions ^12-18 and 11.1% simple interventions ¹⁹. The age of the participants ranged between 63.9 and 76.0 years. Most were female. The duration of DM reported in 55.6% of the studies ranged from 4.8 to 13 years ^{12,13,15,16,18}. Regarding primary results, 77.8% showed improvement in glycated hemoglobin (HbA1c) ^11-13,15-18. In 77.8% of the studies, improvement in foot care (monitoring of sensitivity, hygiene and moisturizing) was seen, which is the main data for DF prevention ^11,12,14-18. Regarding secondary results, only 11.1% ¹² presented data that meant that there were no foot ulceration. The rest did not provide data in this area ^11,13-19, (Table 1).

The duration of the interventions ranged from 1 to 15 months; the number of sessions ranged from 2 to 60; and the follow-up time ranged from 2.5 to 39 months (3.3 years average). Education prevailed in all the studies ^11-19, additionally, 11.1% placed educational posters in offices where they attended the participants ¹⁴. 55.6% provided foot care kit ^11-14,18, 11.1% combined education with Tai Chi ¹³. Another (11.1%) delivered the intervention through telephone sessions ¹⁵. There were those who incorporated the measurement of foot temperature with an infrared thermometer (11.1%) ¹². Another study considered the participation of family members during the intervention (11.1%) ¹⁶. There were those (11.1%) who delivered the intervention through a multidisciplinary team and incorporation of the second hour session dedicated to pharmacotherapy ¹¹. 88.9% of the studies, the facilitators were nurses ^11-15,16-18, followed by DM educators in 44.4% ^11,14,15,19, (Table 2).

Evidence quality: Regarding evidence quality, 44.4% of the studies showed high evidence quality ^12,14,17-18. In these, the risk assessment was classified between low bias risk and unclear bias risk. The rest (55.6%) were classified as medium quality ^{11,13,15-16,19}, because in some of the evaluated criteria they presented a high bias risk (Figure 2).

Adapted from Cochrane Manual of Systematic Reviews of Interventions by the Iberoamerican Cochrane Center (2012).

Source: own-development.

Figure 2. Cochrane evidence quality signaling for selected articles, (2019-2020) (n=9) 

Discussion

In view to the objective of this systematic review, which was to explore the characteristics of the most effective health interventions for the prevention of DF in OA with DM, the following was found: most interventions focused on education about foot care and only one included improvement in the risk of DF (foot cracks, calluses and neuropathy symptoms). This reflects that education and knowledge of foot care (hygiene, moisturizing, monitoring, rest) is critical in prevention of DF, especially in people with neuropathy or loss of feeling in the feet ²⁰.

Almost all interventions used educational sessions on foot care and/or delivery of care kits. More than half showed that participants increased foot care. Therefore, hygiene and moisturizing of the feet reduce injuries due to dry skin and daily feet monitoring warns about changes and injuries (color and temperature of the skin, cracks, among others) ^21,22. However, the studies do not report a reduction in the injuries.

Education on foot care in patients with DM was reported to be effective both in the delivery of written informative material ^12-14,18 and face-to-face sessions ^11-13,15-19 or both combined ^12,13,18. Both modalities involved feedback in person or by telephone, respectively. It seems that both informative material and face-to-face orientation and demonstration accompanied by feedback help participants to carry out more frequent foot care ²³. Perhaps written material constitutes a guide that the participant can review or consult at any moment and as many times as required. Educational sessions offer the participant the opportunity to see procedures and raise concerns. This may be due to the fact that educational materials are an instrument to guide learning through education ²³.

Additionally, just over half of the studies ^11-14,18 provided foot care kits as a strategy that facilitated the process of improving foot care. This is certainly relevant for low-income or older patients who have difficulty obtaining accessories for their foot care, in addition to preventing excuses for not doing so. However, the studies that delivered kits, except for one of them ¹² indicated that it served as a motivator for foot monitoring, the rest did not indicate advantages of such delivery.

Regarding the primary outcomes, almost all studies observed improvement in HbA1c results ^11-13,15-18, critical results in foot irrigation and feeling, which in turn minimized the risk of DF. Hyperglycemia affects the function of the endothelium, which reduces the quality of the production of nitric oxide, which increases endothelial vasoconstriction that manifests in endothelial vascular disease. These lower limb injuries affect blood flow to the degree of hypoxia and damage the nerve fiber (diabetic neuropathy) manifested by altered sensitivity to vibrations, temperature and pain ²⁵.

The number of sessions, intervention period and follow-up time varied among the studies. The longest intervention and follow-up corresponded to ECA (by its acronym in Spanish). Most of the studies were quasi-experimental, as they did not have randomization or a control group, so they were evaluated as studies with medium bias risk.

Only one study ¹⁶ considered the participation of family members in the intervention sessions; the incorporation of family members on health care and education interventions allows having positive progress of family members with chronic diseases tackling the disease, in addition to form support networks ²⁴.

It was not possible to make a decision regarding the best intervention to prevent DF, due to the medium quality of the selected studies. However, elements for the development of a DF prevention intervention program were identified, which included: an intervention period of at least two months of education on foot care with the inclusion of a family caregiver, delivery of materials or kits to facilitate the foot care and assessment of health conditions such as control for HbA1c, presence of sensory neuropathy, peripheral arterial disease and foot status.

Conclusions

When exploring the characteristics of the most effective health interventions for the prevention of the DF in OA with DM, it can be concluded that interventions reviewed as most effective were those that included education and knowledge about the feet care, follow-up telephone calls, printed material and materials (kits) for feet care. HbA1c was the most used physiological indicator to determine glycemic control. The DF risk level was measured in one of the studies only. As well as the incorporation of the caregiver or relatives in the intervention. Evidence quality according to bias risk was medium so it was not possible to determine which intervention was the best to prevent diabetic foot.

Conflicts of Interest

The authors stated there were no conflicts of interest.