A Systematic Review and Qualitative Analysis of Existing Dietary Mobile Applications for People With Chronic Kidney Disease

Abstract

Objective:

The goal of this study was to systematically evaluate the quality of electronic applications (apps) available for chronic kidney disease (CKD) dietary management.

Methods:

The review consisted of (1) a systematic search for all mobile CKD diet apps available on the App Store and Google Play Store, (2) an evaluation to determine how well existing apps met criteria for an ideal app, and (3) a systematic literature review of publications found through Google Scholar, Mendeley, and PubMed that reviewed specific CKD diet apps and the broader field.

Results:

After applying systematic search criteria, 10 unique apps were identified. Ten of 14 criteria considered necessary in an ideal CKD diet app were applied to the 13 apps. Important criteria such as tailoring recommendations to CKD stage or individual dietary needs, tracking nutrient intake, allowing data to be accessible to clinicians, availability on different app platforms, and including CKD-friendly recipes were not consistently available in the apps. None of the apps used the most contemporary nutrition guidelines on which to base their recommendations. While the literature suggests there is demand for CKD diet apps, common shortcomings of available apps including barriers to usability, inclusion of erroneous information, the requirement of a high e-literacy level, user costs, lack of privacy, security, and interactive features, and the inability of caregivers or family members to use apps to assist in patient care.

Conclusions:

The few CKD dietary apps currently on the market for people with CKD have notable limitations in terms of content and software design. Opportunities therefore exist for improving on available CKD diet apps and thereby fulfilling an important unmet need for patients with CKD.

Introduction

THE DIGITAL AGE is revolutionizing modern society and with it health care. Personal electronic devices and ubiquitous access to the Internet with its wide array of applications (apps) offer great potential to improve patient health and healthcare delivery. One important area of interest involves dietary management in people with chronic kidney disease (CKD). The recently updated 2020 Kidney Disease Quality Outcomes Initiative (KDOQI) Clinical Practice Guideline for Nutrition in CKD has helped to establish the importance of adhering to kidney-oriented dietary recommendations to prevent or treat kidney disease and improve health in people with CKD.¹ The guideline also highlighted the importance of tailoring dietary recommendations to the unique needs of each individual.

Internet-based applications offer the possibility of achieving these goals in ways that were not previously available by allowing individuals to easily access food and nutrition databases, count calories, track intake of macronutrients and micronutrients, and follow weight and other indices of nutrition. An ideal app would also allow physicians or registered dietitians secured access to these data if desired. Such an app would be able to help achieve the goals of enhancing both the health-care experience and a patient’s health.²

The aims of this study were to identify existing CKD diet apps, determine how well these apps fulfilled the criteria of an ideal app, and perform a systematic literature review to assess the quality of such apps and more generally the state of CKD dietary or related apps. We performed our analysis with an eye to determining whether current apps adequately fulfill the needs of the CKD population or whether additional work is needed in this area.

Methods

Identification of Existing CKD Diet Apps

Between June and July 2020, a team of reviewers performed a search for available apps on widely used devices including iPhones 7 and X, Samsung Note 10+, and the online Google Play store. The following search keywords and phrases were used: CKD, kidney nutrition, diet CKD, diet kidney, nutrition tracker CKD, CKD nutrition, chronic renal failure, chronic kidney disease, dialysis, dialysis diet. Apps were included if they met the following criteria for a CKD diet app: (1) CKD diet-related, (2) in English, (3) patient-oriented, (4) updated after 2010, and (5) available for download through a major app source or published on in a journal.

Establishing Criteria for an Ideal CKD Diet App

No formal standards exist for designing mobile applications. Therefore, after extensive discussion, a list of 14 criteria was assembled that the study team felt would reflect those of an ideal CKD diet app (Table 1). A review team consisting of biomedical, computer, and multidisciplinary engineering undergraduates supported by an academic nephrologist and a PhD professor of nutrition jointly developed the criteria based on previous experience and expertise with software development, the identified needs of the CKD population and their nutritional requirements. From a software standpoint, availability on standard app platforms, attractive and easy-to-read graphics, ability to store an individual’s data and provide feedback to the developer, data accessibility, and security and Health Insurance Portability and Accountability Act compliance were identified as necessary criteria. In terms of app content, reliance on high-quality nutritional evidence,¹ the accurate tracking of micronutrient and macronutrient intake, tailored recommendations for individual needs, the inclusion of CKD friendly recipes, and ease of accessibility were included. Finally, providing the app at no cost was considered of great benefit. Of note, only 10 of 14 criteria for an ideal app were evaluated by the authors (Table 2) because “attractive and easy to read graphics” was considered a subjective criterion, “security and Health Insurance Portability and Accountability Act compliancy” involved technical issues beyond the scope of this article, “provides motivational feedback” would require patients to log in to be assessed, and “Accessibility and user friendliness for people of all backgrounds” was felt best evaluated through a patient survey.

Table 1.

Criteria for an Ideal CKD Nutrition App

Software-Related

Available on Apple App Store and Google Play Store

Attractive and easy to read graphics

Able to store an individual’s data

Data accessible by clinicians if desired

Ability to provide user feedback

Secure and HIPAA compliant

Accessible and user friendly for people of all backgrounds

Provides motivational feedback

Content

Evidence-based information that can be regularly updated

Tracks micronutrient and macronutrient intake

Recommendations tailored to CKD stage

Recommendations tailored to individual needs

Includes CKD-friendly recipes

Other

Available for free

CKD, chronic kidney disease; HIPAA, Health Insurance Portability and Accountability Act.

Table 2.

Characteristics of Existing CKD Diet Apps

App Name	Free of Charge	User Rating out of 5a	Platform Availability	Academic Sponsorb	Adheres to KDOQI Guidelines(1)	Exclusively CKD Nutrition Focused	Stores Individual Data	Tracks Nutrition Intake	Includes Recipes	Data Accessible by Clinicians	Provides CKD Stage-Specific Recommendations	Personalized Dietary Recommendations	Overall Scorec
“Kidney Diet Foods”	N	1.4 14 ratings	iOS	N/A	N	Y	Y	Y	N	N	N	Y	4/10
“kidney diet recipes”	N	1.3 3 ratings	iOS	N/A	N	Y	N	N	Y	N	N	N	2/10
“KidsKidney Diet”	Y	N/A	iOS	Great Ormond Street Children’s Hospital//NHS Foundation Trust and support//Kidney Care UK	N	Y	N	N	N	N	N	N	2/10
“low phosphorus foods”	Y	2.5 8 ratings	iOS	USDA	N	Y	N	N	Y	N	N	N	3/10
“Renal-diabetes-diet”	Y	N/A	Android	N/A	N	Y	N	N	Y	N	N	N	3/10
“Chronic Kidney Disease (CKD)”	Y	3.4 20 ratings	Android	Mayo Clinic	N	N	N	N	N	N	Y	N	2/10
‘‘My Healthy Kidney	Y	4.1 15 ratings	Android	N/A	N	Y	Y	Y	N	N	N	Y	5/10
“MyKidney Diet Phosphate Tracker”	Y	2.0 2 ratings	Android	N/A	N	Y	Y	Y	Y	Y	N	Y	7/10
“My Kidneys, My Health handbook”	Y	1.0 1 rating	Both	Kidney Health Australia	N	N	N	N	N	N	Y	N	3/10
“CKD (Chronic Kidney Disease)”	N	1.56 24 ratings	Both	USDA//NIH	N	Y	Y	Y	Y	N	N	Y	6/10

CKD, chronic kidney disease; KDOQI, Kidney Disease Quality Outcomes Initiative.

^aUpdated as of April 19, 2021. Provides user ratings and quantity of ratings left on the app description in its respective download source. The app ratings are averaged between both platforms for those apps falling under the Platform Availability category of “Both.”

^bSource of funding or academic institution working in collaboration with the app development team.

^cThe 10 characteristics that were analyzed included being free of charge, availability on android and iOS, adherence to KDOQI guidelines, CKD focused, ability to store individual data, tracks nutrition intake, includes recipes, data can be reportable to clinicians, provides stage-specific recommendations, and if the dietary recommendations can be personalized.

Evaluating Criteria for an Ideal CKD Diet App

Each app was evaluated for the presence of ideal characteristics. The app was checked for any purchase cost; availability on Google Play Store and Apple App Store; whether it references any guidelines or sources; if the app was designed for patients with CKD; if it was able to store patient data; if it allowed patients to track their own nutrient intake; if the app provided recipes to the patient; if the data the patient stored could be shared with a clinician; if the app allowed recommendations to be personalized based on CKD stage; and if the app allowed further modifications to accommodate personalized dietary recommendations.

Systematic Literature Search on CKD Diet Apps

A systematic literature search was performed to identify all articles that assessed the quality of currently available mobile health apps designed specifically as diet apps for people with CKD. The literature review followed the preferred reporting items for systematic reviews and meta-analyses protocol.³ Search keywords and phrases were the same as those identified previously to search for available CKD diet apps and the search was performed using Google Scholar, Mendeley, and PubMed. The search also included the name of the specific CKD diet apps identified (Table 2). Only one trial met eligibility requirements for analysis of bias using the Cochrane Risk of Bias assessment tool.⁴

Results

Identification of CKD Diet Apps and Fulfillment of Ideal Criteria

The 3204 apps originally identified using search terms were narrowed to 10 apps after the exclusion criteria were applied and duplicates removed. Thirteen apps were originally identified but these three apps were delisted before mid-April 2021, so only 10 remained (Figure 1).

Figure 1.

Flow diagram identifying CKD dietary apps of interest.

Four of these apps are exclusively available through iOS platforms, four through Android platforms, and two on both platforms. Characteristics of each app are shown in Table 2. All apps were able to collect user feedback through the application hosts (Apple App Store and Google Play Store). Of 10, 8 (8%) apps were designed exclusively as a CKD diet app. Seven of 10 (70%) were free of charge. Five of 10 (50%) included CKD-friendly recipes. Four of 10 (40%) included personalized recommendations based on patient inputted data. Two of 10 (20%) were available in both the Apple App Store and Google Play Store. One of 10 (10%) offered an option to share health information. Four of 10 (40%) tracked macronutrient and micronutrient intake and provided CKD stage-specific nutritional recommendations. None of the apps adhere to the 2020 KDOQI nutrition guideline. The ability to store individual data was assumed to be included if the app tracked macronutrient and micronutrient intake though this was not confirmed. The sources of information and updates of data are found in Table S1.

In terms of fulfilling the 10 criteria of an ideal app documented in Table 2 (4 of the criteria were not assessed here for reasons described in the Methods), 1 app (“MyKidneyDiet Phosphate Tracker”) met 7 of 10 ideal criteria, 1 app (“CKD [Chronic Kidney Disease]”) met 6 of 10 ideal criteria, 1 app (“My Healthy Kidney”) met 5 of 10 ideal criteria, 1 app (“Kidney Diet Foods”) met 4 of 10 ideal criteria, 3 apps (“Renal-diabetes-diet,” “low-phosphorus-foods,” and “My Kidneys, My Health handbook”) met 3 of 10 ideal criteria, and 3 apps (“kidney diet recipes,” “KidsKidneyDiet,” “Chronic Kidney Disease [CKD]”) met 2 of 10 ideal criteria.

Review of Specific CKD Diet Apps

Of 135,970 articles initially identified, 133 were related to diet and CKD. Articles were initially screened based on title and abstract content. Further screening reduced the number of articles included in the analysis to 10 (Figure 2). Only a few of these articles mentioned specific apps with the remainder providing a broader analysis of CKD mobile app quality and their strengths and shortcomings. Table S2 provides a summary description of articles included in the literature search.

Figure 2.

Preferred reporting items for systematic reviews and meta-analyses flow diagram identifying articles of interest.

The most mentioned app was My Kidneys, My Health Handbook, which provides general information and dietary advice for individuals with CKD. Resources therein include nutritional factsheets, community newsletters, and additional app/Website recommendations, but are out of date or inaccessible directly through the app.^5–8 It was also rated as one of the more usable apps and scored high on the Mobile App Rating Scale⁹ as described by Siddique et al.⁸ However, one consistent negative critique was its lack of advanced interactive features such as providing motivational feedback and changing information based on user input.

Singh et al.⁷ identified only 1 CKD-related app (“Transplant Hero”) out of 400 that the nephrologist reviewers were highly likely to recommend to patients. Sobrinho et al.¹⁰ developed a prototype CKD diet app (not publicly available) to provide people with additional resources to manage their CKD. However, these resources are primarily medication reminders and network opportunities with clinicians, rather than resources for nutritional intake. This research team reported that younger patients found the prototype health app useful and easy to use, though older patients had difficulties navigating the software.

Review of Overall Quality of Existing CKD Diet Apps

The current state of information technology designed to improve care in patients with CKD through Web-based education, short message service texting, and mobile apps was evaluated by Diamantidis and Becker.¹¹ They reported that CKD-related app technology (including CKD diet apps) comes with its own shortcomings such as barriers to usability, inclusion of erroneous information, the requirement of a high e-literacy level, and user costs.

Several additional shortcomings of existing CKD diet apps have also been described related to privacy, security, lack of interactive features, and the inability of caregivers or family members to use apps to assist in patient care.^6,8 Lambert et al.¹² reported that only 10 of 21 (48%) CKD apps designed to provide dietary information were evidence-based, while also noting that the majority of apps were of good technical quality and did not require high levels of health literacy.

Regardless of their shortcomings, demand for dietary CKD apps exists. Fortnum⁵ reported in a conference abstract that a survey of 117 people using My Kidneys, My Health found that many patients were searching for a resource to help manage a variety of CKD-related issues including progression of CKD, dietary treatment options, lifestyle issues, and finding support groups.

In an attempt to disseminate educational resources to patients with CKD, Klein¹³ developed a handout that included several different apps that met the needs for individuals seeking resources for CKD. However, some of the apps that helped tracking nutrient and water intake and provided CKD-friendly recipes were not CKD specific.

Finally, the literature in patients with CKD is mixed but relatively scant on whether diet apps lead to significant improvement in nutritional markers. A systematic review focusing on the effect of mobile apps on nutritional indicators in people with CKD found no statistically significant reduction in dietary sodium, potassium, phosphorus, and fluid intake in active app users.¹⁴ The authors concluded that larger sample sizes are needed to establish the efficacy on dietary intake. In contrast, a food journal app led to significantly increased dietary adherence to a low-protein diet in 20 patients with CKD, though no differences in biochemical indices were seen between participants who did versus did not drop out of the study.¹⁵ Of note, this particular study was assessed to have moderate risk of bias using the Cochrane bias assessment tool owing to incomplete blindness and missing data.

Discussion

The goal of our analysis was to establish the availability and quality of CKD diet apps based on a comprehensive web search, a systematic literature search, and criteria we established for what an ideal app should include. A well-designed CKD dietary app could serve as a valuable resource for people with CKD. The recently updated CKD nutritional guidelines documented that adherence to dietary goals can help prevent or improve complications such as hyperphosphatemia, hypertension, volume overload, and proteinuria and may even slow progression to end-stage kidney disease.¹ On the other hand, the guidelines also recommend avoiding intake restrictions as a blanket measure. Therefore, an ideal app should be designed so that recommendations can be tailored to an individual’s unique dietary needs.

Review of this topic clearly reveals that there is room for improvement and innovation among the current landscape of diet CKD apps. Of the more than 3000 potential mobile apps identified, only 10 met our search criteria. Of these, none fulfilled all the criteria we established for an ideal app with the best performing app being MyKidneyDiet Phosphate Tracker, which fulfilled 7 of 10 such criteria (with 4 other criteria not being reviewed). However, this app focuses primarily on tracking phosphate, and while it does include information on macronutrients, sodium, potassium, and phosphate, it does not track calcium or other micronutrients.

The main advantage of our scoring system in relation to those used in some of the other reports (including Mobile App Rating Scale)⁹ is that ours is specifically tailored for dietary apps in persons with CKD. That is, we were able to include the criteria we thought were most relevant to both patients and their physicians or dieticians. The main disadvantage is that our scoring system is subjective and not validated. However, none of the other systems used were validated specifically for CKD diet apps.

Our literature search (bolstered by additional sources¹⁶) suggests that demand exists for CKD diet apps. However, we also observed that patients and physicians found existing apps to be difficult to use and lacking more interactive features and an evidence-based approach. In addition, none of the apps were based on the updated 2020 KDOQI nutrition guideline. More specifically, only 4 of the 10 apps listed the source of information they used to design their app, and as of April 24, 2021, none of these 4 apps were updated after the 2020 KDOQI guideline update was released. Documenting the data source will be an important part of the development of any future CKD dietary app. The next five most common missing criteria included “recommendations tailored to CKD stage,” “tracks micronutrient and macronutrient intake,” “data accessible by clinicians if desired,” “available on Apple App Store and Google Play Store,” and “includes CKD-friendly recipes.” These criteria are all important as they involve tailoring recommendations to individual needs and severity of CKD, accessibility of app and data to patient and clinician, and enhancing the eating experience by offering different meal options.

Content is not the only important aspect of a CKD diet app. Careful consideration should also go into its software design. Access on several platforms is important for increased accessibility. The option of sharing and storing data with physicians, dietitians, or other healthcare providers could lead to more collaborative patient care. In fact, ensuring that physicians, dieticians, and patients all play a role in the development of a new app will be critical in ensuring its optimal design. App security is essential to prevent hackers from accessing information or encrypting malware into the software and thereby intercepting sensitive and confidential health information or stealing data.¹⁷ Health Insurance Portability and Accountability Act compliance should be ensured. The app should also ideally be able to provide user feedback to the app store or the development team through reviews. Simplicity of design, ease of use, and accessibility are other ideal criteria because CKD is most common in older adults and individuals who are less well educated or who may not have the skills to navigate a more complex app.^18,19 Simple graphics will take up less storage, allow an app to load faster, and improve the ease of use. Hi-def resolution and fundamental color schemes should be used to make the app more appealing. Finally, offering the app free of charge would greatly improve access to people in need with CKD around the world.

Of note, our literature search found a lack of rigorous comparative testing of CKD diet apps which would be explained in part by differences in their quality, design, and intent. Any new CKD diet app should optimally have beta testing performed before being marketed to assess content and software quality and, if feasible, impact on dietary intake and possibly health outcomes. While assessing the ability of the apps to accurately calculate nutrient intake from entered foods is beyond the scope of this article, studies from the non-CKD literature raise this as a valid concern and an important topic to consider in the development of future CKD nutrition apps.²⁰

Our analysis has several limitations. It is possible that relevant apps may have been omitted because they were searched solely through the Google Play store and Apple App store in the English language. Furthermore, because the app searches focused only on CKD-specific diet apps other apps relevant to this topic were not included. Any new apps that were released after the drafting of the manuscript would not have been included in the analysis. Finally, the ideal criteria we chose may be different than those identified by others.

In summary, the few CKD diet apps currently on the market for people with CKD have notable limitations in terms of content and software design. Opportunities therefore exist for improving on current CKD diet apps and thereby fulfilling an important unmet need for patients with CKD.

Practical Application

The handful of dietary apps currently on the market that are tailored to people with CKD have notable limitations in terms of content and software design. Opportunities therefore exist for improving on such apps and thereby fulfilling an important unmet need in the dietary management of patients with CKD.