Globally, 1 in 3 persons and up to 60% in industrialized countries are living with at least 1 chronic disease [1-3]. Furthermore, this share is continuously increasing across the globe due to demographic change and consumption patterns [3,4]. Chronic diseases, including conditions such as diabetes, cardiovascular diseases, and chronic obstructive pulmonary disease (COPD), are long-lasting conditions that can significantly impact a patient's quality of life and are a key driver of escalating health costs in both developed and developing economies [5]. Diagnosing and treating chronic conditions comes with substantial uncertainties for patients, families, and caregivers [6]. The high complexity of chronic care, for instance, raises uncertainty regarding whether patients with chronic diseases will respond to a selected treatment in the way a priori expected and, in the event they do, whether it is the most efficient one [7].

Patient-reported outcome measures (PROMs) and patient-reported experience measures (PREMs) have been used for over 20 years, but have become increasingly widespread and accepted only in recent years [8], as reflected by their increasing usage in oncology [9-11] and orthopedics [12-14]. The use of PROMs in monitoring interventions has, for instance, shown benefits in terms of increased survival rates, lower hospitalizations, improved health-related quality of life in oncology and reduced fatigue, and improved health-related quality of life in orthopedics [15,16]. PROMs are questionnaires that allow valuable insights into the patient’s perspective of living with a (chronic) disease as they reflect the patient’s own perception of their health status [17,18]. PREMs are questionnaires used to gather information from patients about their personal experiences and perceptions of the care and services they have received [19]. With electronic PROMs (ePROMs) and electronic PREMs (ePREMs) being reported and used more frequently in the last few years [20,21], usage for population health purposes appears more in reach but has rarely been examined [22].

PROMs and PREMs might have care improvement potential in the field of chronic diseases due to their information value for patient empowerment, including self-management and shared decision-making, which could influence treatment adherence and lifestyle choices [23]. However, PROMs and PREMs have rarely been used in routine chronic care due to the unspecified timeline and the complexity of implementation [24]. Due to the high relevance of this topic, the OECD (Organisation for Economic Co-operation and Development) PaRIS (Patient-Reported Indicator Surveys) initiative focuses on collecting and analyzing PROMs in patients with chronic diseases across 18 countries, starting their trial phase in 2023. The initiative does not cover Germany [25]. The present study, “PROMchronic,” aims to fill the research gap by evaluating the usage of ePROMs and ePREMs in the German chronic disease population for 4 selected chronic disease profiles.

Furthermore, providing patients with information on their health status based on PROMs in reference to a comparable peer group is rarely done [26,27]. Yet, specific information about patients’ health status is crucial because it can help patients better understand their health conditions and enable decision-making and overall patient empowerment. When patients are well-informed about their health, they are more likely to adhere to treatment plans and achieve better health outcomes [28]. Patients can use this information together with their health care providers to set realistic goals for their treatment, monitor their progress, and identify areas where additional support is needed.

Our study aims to evaluate the potential benefits of the structured and population-based use of ePROMs and ePREMs to improve care for chronically ill patients in Germany. First, we evaluated whether and how representative the response to the digitally collected questionnaires is and thereby investigate PROMs as a tool for health system performance assessment (HSPA). Second, we assessed if low-value care elements can be identified in today’s care for chronically ill patients across Germany. Third, we analyzed patients’ understanding of and reactions to individualized patient-reported outcome (PRO) feedback. To achieve these objectives, this study aims to answer 3 overarching research questions and their subquestions (Textbox 1).

This is an observational prospective cohort study covering the 4 chronic diseases: asthma, COPD, diabetes types 1 and 2, and coronary artery disease (CAD). As shown in Figure 1, the first point of contact will be a letter from the insurer to insured patients selected for their chronic disease. A patient can then sign up digitally for the study via a QR code or web-based link. For each of the different diseases, a distinct patient pathway is automatically assigned, with a registration process followed by some background questions and the respective generic and disease-specific PROMs and PREMs. The study covers a timeframe of 1 year, split into 4 time intervals with further information and reoccurring questionnaires. The time intervals are split into smaller tasks to facilitate the answering process for participants. The first interval includes self-registration and a baseline assessment of health behavior. A few weeks after responding to the first set of questions (Figures 1A and 1B), patients will receive a report with their individual PROM scores compared to a peer group and will be surveyed on the comprehensibility of the PRO report (Figure 1C). From the second interval onwards, patients will also receive their individual PRO results longitudinally. Lastly, following the individual PRO feedback report, participants will be surveyed regarding their health behavior (Figure 1D). After 1 year, the primary data collection process is finished, and patient-reported data will be merged with health insurance data. Further explanations of subgroup definitions can be found in the Statistical Analysis Plan (Multimedia Appendix 1).

This study will recruit patients all over Germany who are insured by one of the largest statutory health insurers in Germany (BARMER). The BARMER represents more than 10% of the German population. After the identification of individuals based on their chronic disease profile, validated PROM sets are used digitally to regularly survey patients with asthma, COPD, diabetes, or CAD on their health outcomes as well as their experience with the health care system.

Patients are eligible for participation in the study if they are above the age of 18 years and have at least 2 outpatient consultations in 2021 documenting a confirmed chronic disease diagnosis of 1 of the 4 focus diseases. Additionally, for type 1 diabetes patients, at least 1 insulin prescription must be documented in 2021. To contact patients and enable the linkage of health insurance data, patients must be insured by BARMER health insurance all year in 2021. Patients enrolled in a Disease Management Program (DMP) as well as patients not enrolled in any DMP are eligible. However, enrolment in more than 2 DMPs is not permitted to avoid multiple invitation letters and cross-over groups.

Eligible participants will be participating in the study for a maximum of 4 quarters, starting with the first access to the digital questionnaires, followed by quarterly digital surveys split into several tasks (compare Figure 1). To start the survey, participants register with their study pseudonyms received in their enrollment letter and then share basic demographics. Each survey period contains 4 tasks to be completed by participants, defined as sets of questions that each will take 5-10 minutes to complete. The participants will receive individual reports on their patient-specific and peer group outcomes (PRO feedback) and will be asked about the comprehensibility of the report. Following the report, the participants receive a set of questions regarding their health-related behavior.

The initial enrollment letter is sent to 200,000 insured patients, 50,000 for each of the selected chronic conditions. Diabetes type 1 and type 2 are considered jointly, as there is no differentiation in the selected PROMs. Patients with all chronic diseases are allocated to groups based on their participation in DMP (DMP or non-DMP group). Prior experiences suggest that around 30% of patients react to invitations to participate in research by their insurer [29-31]. Two-thirds of initial participants are expected to allow follow-up contacts and processing of their health insurance data, and around 40% of these patients will continue participating in all the follow-up surveys after receiving reminders for each task. Therefore, after accounting for nonparticipants and participants with no complete survey data, we expect a complete data set for 16,000 participants. However, the first research question will investigate response rates, as there is no evidence on this population yet.

BARMER Health Insurance will send out enrollment letters based on a random selection of BARMER-insured patients following the defined eligibility criteria. Matching of DMP- and non-DMP participants will be done according to the steps provided in Textbox 2.

The output is a data set containing matched pairs per indication. The first 25,000 matching pairs for each chronic condition will be selected. Diabetes type 1 and type 2 are considered jointly, with patients having diabetes type 1 selected first (approximately 6600 matched pairs are expected), followed by supplementing the remaining required matched pairs with patients having diabetes type 2.

An initial enrollment letter including the study explanation, a QR code, and a link as an invitation to participate in the study will be sent to insured patients in October 2023 (Multimedia Appendix 2). The enrollment survey and, thereby, the recruitment period will be open for 2 months.

The study will be conducted in accordance with the Declaration of Helsinki and was approved by the Charité’s Ethic Committee, Berlin (EA2/035/23). All potentially eligible participants will be approached to offer their informed consent to participate in the study as well as to allow linkage of their insurance data for further analysis. This protocol is version 1, dated January 10, 2024. Any changes in the study design will be communicated to all project partners.

Informed consent must be provided digitally before patients can participate in the study. By signing the informed consent, patients allow contact for follow-up surveys via email and to process their survey data for academic research purposes. Additionally, patients are asked to sign a second consent form for processing and linking their insurance data to their survey data. The second consent form is optional and is not a prerequisite to participating in the study. Patients will be free to withdraw from either one of the consents without stating a reason until the anonymization of the data. Through the anonymization of the primary and secondary data before the provision of data sets to research institutions in the project, patient identification will not be possible. If the patients withdraw their consent for participation, all their data will be deleted. Consent forms can be found in Multimedia Appendix 3. Participants are not reimbursed for their participation.

The primary end point (research question 1) of the study is sufficient study participation to determine the representativeness of the results. As expected, study participation will vary depending on gender, age, and diagnosis, but this can be compensated for by weighting the study participants according to structural information on the target population.

Within our study, data on health care usage is available for both participants and the whole target population. Weighted measures of health care usage from participants will be compared with measures of health care usage of the complete target population and will be assumed to be formally representative if the weighted measures from participants fall within the 95% CI of the same measures based on data from the complete target population.

Secondary end points are the end points to answer research questions 2 and 3 (Textbox 3; Figure 2).

Figure 2 represents how PROMs and PREMs can be combined into one value of care indicator, for example, if PREMs and PROMs are both average or above (up to 1 SD), care is suspected to be high-value, whereas if PROMs and PREMs are below 1 SD of the average, care is suspected to be low-value. Since for each disease group, a disease-specific PROM will be used next to a generic PROM, the assessment of low- and high-value care across diseases will be conducted by using the generic PROMs. Moreover, the disease-specific PROMs will be used to create low- and high-value care categorizations on a detailed level within a disease group. Adding cost data as a third dimension to the value of care framework (as described in the Statistical Analysis Plan, Multimedia Appendix 1) then enables a clear distinction between patients considered to have received low-value care and patients who received high-value care. A more detailed description of the outcomes can be found in the Statistical Analysis Plan (Multimedia Appendix 1).

There are 2 main data sources used in this study. First, primary data will be collected from the participants’ surveys. Second, secondary data from the cooperating health insurer, BARMER, will be used. The primary data collection is conducted via digital surveys, which include different questionnaire categories, namely PROMs, PREMs, comprehensibility of the PRO feedback, and questions on patients’ health behavior. Additionally, an anchor question using the Global Rating of Change scale [33] with 5 answer options is included to assess changes in health status.

An overview of all selected survey items, including the selected validated PROMs, can be found in Figure 3 and is described in more detail in the following paragraphs.

The study is monitored by the German research center “Deutsches Zentrum für Luft- und Raumfahrt” (German Aerospace Center). Quarterly status reports are provided by the project team. Status reports include an overview of the achievement levels of the milestones defined prior to the start of the study.

The management of the study is overseen by a project team from Technical University Berlin. The project team is composed of researchers responsible for the study's design, representatives from the participating BARMER health insurance, the technical service provider Oncare, and the evaluating aQua Institute. Regular updates on the study's status are provided to the sponsor.

Adverse events are not expected as the medical treatment of patients with chronic care is not affected. The effects of the PRO feedback intervention are one of the primary end points, and the results will be monitored and published.

Any substantial amendments to the protocol will be submitted to the ethics committee (see below) and all relevant regulatory institutions. Additionally, any amendments to the study design, timeline, or budget need to be communicated to the study sponsor, and approval by the coordination center must be obtained.

The results of this study will be disseminated via publications in peer-reviewed journals and presentations at relevant conferences. Moreover, the funding institution (Innovation Fund of the Federal Joint Committee) will receive an evaluation report that includes the findings of the study as well as interim reports on the study’s milestones. All results will be aggregated, with no opportunity to reconnect on an individual patient level.

The study aims to fill the gap in the literature on large-scale usage of ePROMs and ePREMs in patients with chronic diseases. First, the study protocol details how the representativity of the responses to ePROMs and ePREMs will be assessed over time in different subgroups. This foundational groundwork will help with future targeted efforts and the mitigation of representativity issues. Second, the study protocol identifies how PROMs and PREMs will be used to uncover potential low-value care for patients with chronic diseases. The results can thus inform future investigations on activities for low-value care reduction. Third, it introduces how individual PRO feedback can be shared with patients with chronic diseases and provides insights into the usability and usefulness of PRO feedback. The results of the evaluation can thereby aid the understanding of this specific PRO feedback mechanism.

ePROM collection will increasingly be the standard for capturing patients’ perspectives on treatment outcomes as well as their own health status. It was previously shown that the administrative burden for patients and health care providers can be significantly reduced through the collection of ePROMs compared with phone- or paper-based collection, while response rates and the completeness of data collection remain high [51]. The results of this study will fill the research gap in terms of the representativity of the patient population through ePROM and ePREM collection, for which no previous evidence exists. While this study uses ePROM to measure care quality variation, most of that research was focused on oncological studies [52]. This study aims to fill the research gap on measuring care quality through ePROM and ePREM usage in patients with chronic diseases. Other studies have shown, that working with PROMs can improve care by significantly reducing low-value behavior [53,54]. Additionally, the use of ePROMs and ePREMs can enable (almost) real-time, individual PRO feedback [55-57]. Providing PRO feedback is one way to enhance the use of PROMs in clinical practice and shared decision-making [58]. Previous studies indicate that patients who reviewed shared information on their PRO outcomes are more engaged and actively participate in their health care, but they have not investigated direct-to-patient feedback in patients with chronic diseases [59,60].

There are some limitations to the study that need to be considered. One limitation is the potential for nonresponse bias, as patients who choose to participate in the study may differ from those who do not. However, given the access route via large-scale, randomized health insurance paper-based outreach, we hope some participants who would not take part in studies in a clinical study will be accessed. Moreover, it is one of the study’s aims to detect the representativeness of the responders. Given that the letter and questionnaire will be in German, we anticipate that non-German speakers will be excluded from the study, which unfortunately could not be addressed via the digital solution, the adjustment to letters, and the low availability of validated PROMs in other languages often spoken besides German in Germany (eg, Russian or Turkish). Moreover, respondents to the study might do systematically better in terms of their PROMs and PREMs results, which cannot be assessed if there are no other systematic differences between the responder and nonresponder population [61]. This could also be the case if the monitoring itself improves health outcomes, as suggested in the current literature [62,63].

The broader implications of this study are insights generated for (1) ePROM and ePREM usage among patients with chronic diseases globally and specifically in Germany, as well as (2) cross-country learnings. (1) The expected benefits of PREM and PREM usage among patients with chronic diseases were previously stated by experts, while a lack of evidence in the treatment of chronic diseases exists [22]. This study will examine if and to what extent digitally collected PROMs and PREMs as well as automatically generated PRO feedback could strengthen patient empowerment, informed shared decision-making, and behavior changes in patients with chronic diseases. (2) Given that the OECD PaRIS study will assess PROMs and PREMs across many countries besides Germany, the results of this study can enable Germany to be part of this research community and to benchmark its health care system against those of other OECD countries. Long-term benchmarking results across countries and within Germany can have implications for health care spending based on patients’ needs and care reorganization while raising awareness of care value.

This protocol is version 1, dated October 5, 2023. Patient recruitment will begin with BARMER's letter dispatch around October 11, 2023. The collection of survey data will be finished by September 30, 2024. The study is expected to run until June 30, 2025.