Design

A systematic review was carried out of the clinical trials found in the literature following the parameters of composition and organization for studies of this kind in conformity with the guidelines of the PRISMA ⁹.

The review was registered in PROSPERO with registry number CRD42020175142.

Search outcomes

The sources used to carry out this research were Pubmed (MEDLINE), Embase, The Cochrane Library and CINAHL. The search strategy used was "nursing intervention AND informal caregiver".

Original studies were included with the following inclusion criteria: (a) experimental research design (randomized controlled trials and clinical trials); (b) published in English or Spanish; (c) published between January 2014 and December 2019 (d) participants: informal caregivers of patients c) intervention: nursing interventions to reduce overload in informal caregivers; d) outcome measure: health-related quality of life, levels of depression and anxiety of informal caregivers.

Studies on caregivers of patients with neuropsychiatric pathology were excluded.

PRISMA recommendations were followed to inform the search process ^{9) .}

Two reviewers performed an independent title and abstract assessment of each article for article selection. A third reviewer was present to resolve disagreements. The PRISMA flow diagram shown in Figure 1 details the processes involved in study selection. Based on the database searches, we identified 492 records, of which 69 duplicates were removed. Of the remaining 423 records, a selection was made after reading the title and abstract, which conditioned the exclusion of 328 records (those articles with content unrelated to the research or meeting exclusion criteria were excluded). Ninety-five studies were examined in their entirety and 77 were discarded because they did not provide results or were not related to the reduction of overload. The final count of articles included in this review was 18 (Fig 1).

Figure 1. Flowchart of the review. 

Quality assessment

Assessing the risk of bias is one of the problems that can arise in the course of any systematic review. To assess this risk and the quality of the randomized clinical trials found, the Jadad scale has been used ¹⁰.

This scale is based on analyzing three quality criteria within a study: randomization, blinding and liability (dropout and withdrawals), and assigning a certain score to the studies according to whether the different criteria are met.

Taking this scale into account, we assigned 1 point if randomization was mentioned and 1 additional point if the randomization method was appropriate. In addition, we deducted 1 point if the randomization method was inappropriate. Regarding blinding, we assigned 1 point if blinding was mentioned, 1 additional point if the blinding method was appropriate, and again deducted 1 point if the blinding method was inappropriate. Finally, we assigned 1 point if there was a description of loss to follow-up and dropouts from the study.

The Jadad scale performs a ranking from 0 to 5; if the Jadad score is ≥3 points, the trial is considered a high-quality investigation, whereas if the Jadad score is ≤2 points, the study is considered of low quality ^10)(11)(12.

Extraction and analysis of the data

For the extraction of data from the studies that we found, we analyzed the following independently: a) basic characteristics of the article (year, author, and research design), b) characteristics of the study sample, c) type of intervention, and d) comparative results.

Synthesis of the data

We decided to use an analysis of the narrative to describe the results of the systematic review based on the highest level of evidence, including only randomized clinical trials (RCT). This technique was chosen instead of a quantitative meta-analysis of the dynamics of the interventions because the duration and follow-up times with patients varied from one study to another. Also, the number of studies with consistent results that were found and included limited the possibility of carrying out a meta-analysis.

Description of the studies included

The eighteen studies analyzed were carried out in Australia (n=3), the United States (n=7), Asia (n=4), Africa (n=1), Europe (n=2), and Canada (n=1).

The shared goal of all the studies analyzed was to assess the impact of interventions on informal caregivers. The variables treated included caregiver load, depression, anxiety, anguish, caregiver skills, and well-being.

In all of the studies the control group received normal care.

Characteristics of the interventions

Almost all the interventions were designed to acquire knowledge about care and self-care, as well as to identify unsatisfied needs, using information and communication technologies (n=8).

A number of different tools were used to carry out the studies. These included online platforms and applications (n=2) ^13,14, telephone contact (n=3) ^15)(16)(17, home visits (n=1) ¹⁸, a combination of telephone contact and home visits (n=2) ^19,20, attendance of psychoeducational sessions (n=6) ^{(21)(22)(23)(24)(25)(26}, distribution of a self-help manual (n=2) ²⁷,reading of a photocomic book (N=1) ²⁸, information on the instruments used to monitor patients in intensive care (n=1) ²⁹ , and physical exercise (N=1) ³⁰ .

Results of the nursing interventions

For a better analysis, the interventions found and the outcome measures of each study will be described in different sections.

Interventions based on information and communications technology

We found a total of 7 studies that may be classified into this category.

In the study of Núñez-Naveira et al.¹⁴, they used a mobile application called “UnderstAID” which was accessible with any device connected to the internet. The app included a learning section with information about pathologies, how to provide care, and tools for self-care. The app provided caregivers the opportunity to use a calendar to record visits and daily tasks, as well as offering an interactive network to maintain contact with other caregivers.

Moskowitz et al.¹⁶ carried out an online intervention, designed to teach caregivers about positive emotional regulation. In the same line, Kales et al.¹³⁾ also developed a platform to provide information, establishing a system to delivery daily messages intended to encourage caregivers to communicate and seek support when needed.

The intervention of Bakas et al.¹⁵ was based exclusively on telephone calls. Prior to this the participants were given an informative leaflet and a resource guide with a verification checklist. And in the study of Heckel et al.¹⁹, 3 calls were made to provide support and information from a cancer council.

Other studies combined telephone contact with home visits. Pfeiffer et al.¹⁷ offered an intervention with home visits and telephone follow-up. The aim of the visits was to fashion an individualized plan to identify the unsatisfied needs of the caregivers regarding information and training. Using the same methodology, Tanner et al.²⁰⁾ made 2 home visits, to determine unsatisfied needs of the caregivers with the aim of prioritizing these and creating an individualized care plan. The first visit was followed by monthly calls to maintain the commitment of the care team. The frequency and intensity of additional contacts were determined by need and the families.

The results of two other studies Heckel et al. and Tanner et al.^19,20) showed no effect on caregiver overload, nor were there statistically significant differences in comparison with the control groups in terms of overload, depression, or quality of life. However, in comparison to the control groups there was a reduction in the unsatisfied needs of the caregivers.

The research carried out by Heckel et al.¹⁹ on caregivers at risk of depression, the intervention did have a positive effect on caregiver self-confidence.

In contrast, in the studies of Bakas et al., Moskowitz et al., Núñez-Naveira et al., and Pfeiffer et al.^{14)(15)(16)(17} there was a significant reduction of both depression and anxiety.

In the study of Kales et al.¹³, the caregivers showed a reduction in the level of anguish. However, for the items of caregiver stress, depression, load, and communication there were no relevant differences between the groups.

Self-help manuals

There were two studies that fell into this category. The first, carried out by McCann et al. ²⁷, caregivers were given a written manual based on self-help principles. The effectiveness of the guided self-help manual, derived from cognitive behavioral therapy, in reducing emotional expression of depression by caregivers was assessed, showing a general improvement in comparison to the control group that received standard support.

In the study of Gallagher-Thompson et al.²⁸ a photocomic book was distributed to a Hispanic population in the United States, which depicted characters going through difficulult circumstances and presenting the reader with coping skills and approaches to solving problems, so as to improve depression and relieve stress. The results demonstrated that the material was perceived by the target group as supportive.

Group psychoeducational intervention

The 6 studies included in this category showed similarities in objectives and methodologies, providing information and training to the caregivers through psychoeducational programs^{21)(22)(24)(25)(26} In some cases, they also complemented the sessions with telephone follow-up²³.

In general, psychoeducational interventions reduced the caregivers' overload and improved their quality of life, in comparison to the control group^21-24. Other variables that showed improvement included mourning²⁴, attention to hygiene, and mobility²⁵. However, in the study of Rodríguez-Gonzalo et al.²⁵⁾ the variables of overload, physical and mental health, and social problem-solving abilities did not improve.

There is some controversy regarding depression, as in one of the studies a reduction at 6 months and 12 months was followed by no measurable improvement at 18 months²⁴.

Yu ²⁶⁾ carried out a study on the use of a case-management model (HSC-CM). The intervention focused on 3 components of service: exhaustive assessment to identify caregiver needs, case management to provide coordinated, uninterrupted care, and education based on a personalized multidisciplinary group to cover the needs of the caregiver. The results demonstrated a significant improvement in the overload index of the caregivers, their vitality, their social role, and their general well-being.

Another methodological focus was that used in the study of Hendrix et al.²². The authors used a protocol (Enhanced-CT) to measure the engagement of informal caregivers in a single session. They worked with two components: the management of patient symptoms and caregiver stress. For the first component, a nurse provided training on starategies for symptom management. If the patient had no active symptoms, the discussion focused on their prevention. The nurse also provided training on care-providing techniques if needed, and encouraged the caregivers to identify and discuss areas of homecare that they found troubling. The results showed short-term improvement in caregiver stress and preparedness for care, but not in psychological well-being. In the other study combining education with telephone follow-up, there was seen to be an improvement in the caregivers' overload index ²³.

Individual psycho-educational intervention

We examined two articles reporting individualized psycho-educational interventions.

In the Chiang et al.²⁹⁾ study, information was provided to the caregivers on techniques and instruments used with patients to maintain their clinical stability in the intensive care unit setting. This individual psycho-educational therapy obtained results that included lower scores on the DASS scale of depression and anxiety.

The study carried out by Aoun et al.¹⁸ , in contrast, involved nurses making two home visits to speak with the caregivers so as to identify the areas in which they needed the most support. In this manner they determined the greatest needs and agreed upon actions and solutions and put a joint action plan in place. In this study the intervention group showed a significant reduction in overload after the support received in the home visit.

Physical activity intervention

In the only study found using this kind of intervention, that of Cuthbert et al.³⁰ , the physical activity program for caregivers involved attending an exercise class twice a week. Improvements were seen not only in physical health, but also in anxiety, depression, and quality of life.