Setting and design

This is a retrospective cohort study using routine data from the outpatient ID practice in Nijmegen, the Netherlands. Since 2015, the outpatient ID practice has registered the provided specialized medical care for people with ID in electronic patient health records. All patient encounters have been registered electronically using a health information system (TransHIS). This system registers the reason for consultation and the main health problem(s) during consultation according to the International Classification of Primary Care, Second Edition (ICPC-2; WONCA International Classification Committee, 1998). Furthermore, ID physicians added clinical entries in an electronic journal.

The outpatient ID practice collects informed consent (opt-in) for the use of patient data for research purposes since 2020. For patients who visited the practice before 2020, informed consent was obtained via an opt-in procedure. Informed consent forms were composed in conformity with the GDPR (General Data Protection Regulation) in easy-to-read language (see Supplementary Forms S1 and S1b). If the patients did not have the capacity to consent (e.g., children or people with moderate to profound ID), their legal representative signed.

This study extracted data from the health records of patients who visited the practice between April 2015 and March 2021 when informed consent was present (preregistration https://doi.org/10.17605/OSF.IO/W8GA7). The Medical Ethical Committee (CMO regio Arnhem – Nijmegen) waived the need for further ethical assessment [2020-6090].

Study population

The patient population of the outpatient ID practice has a varying level of ID from mild to profound. Two groups of patients receive care from the outpatient ID practice in Nijmegen. The first group (consultation visit [CV] group) comprises patients referred to the outpatient ID practice by a medical professional, often a GP. These patients have a health complaint or problem requiring ID-specific expertise, thus having a specific, active care demand. The second group (health check [HC] group) comprises patients who have an etiological diagnosis of their ID (e.g., 22q11 syndrome) and visit the outpatient ID practice for proactive health checks related to the etiological diagnosis. These patients are generally referred by a developmental pediatrician and younger in age. Because of the different reasons for visiting the outpatient ID practice, the results for the two groups will be described separately.

Data

Data from initial consultations were extracted from the electronic medical records by the Radboudumc Technology Center (RTC) Health Data of the Department of Primary and Community Care. Data were pseudonymized and provided to the research team. These records include information on the reason for consultation, anamnesis, physical examination, evaluation and conclusion, and additional actions, registered in ICPC-2 codes and written text clinical entries in the electronic journal. Extracted data consisted of patient demographics, reasons for initial consultation (entered at registration), health-related problems identified during initial consultation, and disciplines involved following initial consultation. The reasons for initial consultation were extracted by combining two types of data: (1) registered ICPC-2 codes on the reasons for initial consultation and (2) clinical entries in the electronic journal (Table S1). The clinical entries consisted of open text and were manually coded by the first author using ICPC-2 codes to facilitate merging the two types of data. After merging, the complete list of reasons for initial consultation was grouped into three types: medical-, psychological-, and context related (Table S2). Medical problems concerned for example problems related to the digestive or cardiovascular system, psychological problems could be behavioral or sleep problems, and context-related problems concerned for example problems with work, housing, or social contacts.

The health-related problems identified during initial consultation were extracted by combining information from both the ICPC-2 codes assigned by the ID physician during initial consultation and the clinical entries. The health-related problems mentioned in clinical entries were coded, following a self-developed consensus coding scheme grouping medical-, psychological-, and context-related problems using ATLAS.t.i. software, by three researchers (two ID physicians and the first author; intercoder agreement = 72%). Cases of doubt were discussed with all coders until consensus was reached. The ICPC-2 codes registered by the ID physicians on health-related problems identified during initial consultation were also grouped following the three types and combined with the health-related problems identified in the clinical entries. This resulted in a complete list of health-related problems identified during initial consultation. Additionally, an automated search was performed in ATLAS.t.i. to identify disciplines involved after initial consultation on advice of the ID physician.

Analyses

Analyses were performed separately for the two groups of patients. First, the (number of) different types of reasons for initial consultation were explored using descriptive statistics. Thereafter, we described the reasons that were most prevalent within the three types (medical-, psychological-, and context related). Second, descriptive analyses were performed to explore the (number of) different types of health-related problems identified during initial consultation. To explore a possible pattern between the reasons for initial consultation and the health-related problems identified during initial consultation, a cross-tab analysis was performed for the CV group. Third, to identify the professionals who were involved for referral, assistance, examinations, or treatment after initial consultation, descriptive analyses were performed. IBM SPSS Statistics version 25.0 was used for all statistical analyses.

Demographics

At extraction date, records from 526 patients were available for analysis and were asked for informed consent. A total of 128 patients provided consent and data from their health records were used for this study, with nonresponse to the informed consent being the main reason for exclusion. (Figure 1). The sex and age distribution in this study's population is representative of the total patient population at the outpatient ID practice.

Of the 128 included patients, 91 (71.1%) belonged to the CV group and 37 (28.9%) to the HC group (Figure 1). Table 1 presents descriptive statistics of the study population for the two groups separately. The median age of patients in the CV group was higher than that of patients in the HC group: 25 (IQR: 18–40) versus 17 years (IQR: 7.5–21) years, respectively. In the CV group, 80% were younger than 50 years, with the majority between 18 and 34 years (46.2%). In the HC group, all patients were younger than 50 years at initial consultation, with the majority being younger than 18 (54.1%). Of the patients in the CV group, 34.1% had a known etiological diagnosis, whereas in the HC group the corresponding figure was 89.2%.

Reasons for initial consultation

Health-related problems identified during initial consultation

Interpretation of findings

This study shows that people with ID often experience multiple and multifaceted health problems at the same time. The patient's history and context, in which ID is an underlying factor, play a major role in adequately assessing health problems. It is essential to go beyond medical views and assess health complaints in an integrated way. This includes taking into account the way ID can influence all levels (physical, mental, contextual) of the experienced health issue within the context of everyday life. This is important, because ID, related comorbidities, and the patient's context can influence the expression of symptoms, which can complicate the diagnostic process and treatment of various other medical and psychological problems. These problems might go unnoticed if the focus is on just the ID or on a specific medical or behavioral problem, risking over-, under- or misdiagnosis, and -treatment (Mason & Scior, 2004). Despite the broad focus on medical-, psychological-, and context-related issues, GPs have acknowledged to experience challenges in treating patients with ID (Lennox et al., 2000; Phillips et al., 2004) This study indicates that this is where specialized medical ID expertise, such as provided by ID physicians, can make a difference in improving healthcare for this patient group.

Professionals with specialized medical ID expertise, such as ID physicians, are of value in assessing health complaints in a holistic way, including the specific multimorbidity of people with ID, their context, special medical and psychological care needs, and the etiology of ID (Moonen et al., 2022). This expertise can be seen as complementary to the expertise of the GP. Effective collaboration between both professionals will help improving the healthcare as well as reducing the burden on either profession (Tinselboer et al., 2012). The referral reasons of the CV group indicate that GPs often refer to specialized ID physicians in the case of psychological problems, which frequently concern behavioral problems, suggesting that GPs especially encounter challenges in assessing these problems in people with ID. Dutch GPs are not always aware that they can refer to specialized ID physicians when facing these challenges. Patients were also referred to the outpatient ID practice without specification of a reason other than having ID. This could be because GPs often suspect that ID play a role in patients' health complaints, but do not know in what manner. A qualitative follow-up study can investigate this further.

A possible explanation for the referral reasons being narrower than the problems identified during initial consultation could be that problems are overlooked or “diagnostically overshadowed” by the ID (Beange et al., 1995; Lennox et al., 2007; Mason & Scior, 2004). This concerns the tendency to address symptoms primarily to the ID, which might contribute to missed diagnoses. Misunderstandings on how a person with ID expresses themselves, or reacts to stress, overburdening, and overstimulation might result in incorrect diagnoses as well. Physicians without specialized ID expertise may not always recognize the presence of ID in their patients since this is often not registered, or know the multiple ways in which an ID can influence the presentation of health-related problems. This increases the risk of misdiagnosing complaints and applying diagnostic processes and treatments that are not tailored to the patient with ID (Pouls et al., 2023).

This study identified 25 different healthcare professionals that can be involved in referral, assistance, examinations, or treatment, which indicates a significant need for combined expertise in providing medical care for people with ID (Ervin et al., 2014). This is indicative for the need of multidisciplinary approaches in the healthcare of people with ID (Meijer et al., 2004). The broad range of healthcare professionals that people with ID can encounter makes it imperative that mainstream professionals are equipped with some basic tools and skills to provide effective and compassionate care for this population. Awareness that ID can cause different presentations of health problems, that people with ID have complex medical care needs, and that the expertise of specially trained medical professional is available would help both patients with ID and healthcare professionals. Furthermore, medical professionals should be able to recognize a patient with ID. This can be included in both pre- and postgraduate training for medical and paramedical professionals. Furthermore, teaching medical professionals about how to assess the combination of medical-, psychological-, and context-related problems and how ID can be the underlying interaction in this interplay.

Strengths and limitations

This study used routinely collected data at the outpatient ID practice that was not collected for research purposes specifically. This resulted in two limitations. First, the registration was not fully standardized, leading to missing or inadequately registered data. Second, a GP system was used that did not allow for registration of multiple reasons for consultation and did not include ID-specific codes for registered reasons of consultation. These items were added by the ID physicians in free-text clinical notes and included in our data as described in the Methods section. This allowed us to obtain better insight in consultations and gave a first idea about what specific ID-related codes could be helpful to add in future development of the registration system. The manual coding of clinical entries on health-related problems identified during initial consultation in terms of broader categories (medical-, psychological-, and context-related) limited insights into the specifics of these problems.

The start of the COVID-19 (Coronavirusdisease-19) pandemic challenged obtaining retrospective informed consent, which impacted the number of patients that could be included. Consequently, this study's findings are based on 24.3% of the patients who visited the outpatient ID practice before the extraction date. The sex and age distribution in this study's population is representative of the total patient population at the outpatient ID practice, but limitations in data about the ID population make it difficult to judge the generalizability of our results.

This study has been performed in the Netherlands, and it is important to acknowledge that the findings might not be directly applicable to other countries. Despite this limitation, the Dutch setting provided a unique opportunity to explore the value of specialized medical ID expertise and gave insight in the often multifactorial undiscovered health-related problems that people with ID encounter.