With this study, the investigators aim to answer the following research questions:

1. In what percentage of cases does the diagnostic process conducted during a fatigue consultation at the internal medicine outpatient clinic contribute to a somatic diagnosis?
2. What are the experiences of patients presenting with fatigue at the internal medicine outpatient clinic when a consultation, including diagnostic testing, does not lead to a diagnosis?

To address question (1), the investigators will conduct a retrospective data analysis using information from HiX, an electronic health record (EHR) system.

To answer question (2), the investigators will conduct a prospective qualitative study through interviews.

Chronic fatigue is a prevalent and challenging symptom, affecting an estimated 30% of the general population in the Netherlands for periods longer than six months. Despite its frequency, only a small proportion of patients presenting with fatigue receive a somatic or psychosocial diagnosis, leaving many cases unexplained. This underscores the complexity and subjective nature of fatigue, as well as the need for better understanding and management of this condition in secondary care settings.

The aim of this study is twofold. First, it seeks to determine the effectiveness of diagnostic procedures performed during fatigue consultations at an internal medicine outpatient clinic in contributing to a somatic diagnosis. Second, it aims to explore the experiences of patients for whom these consultations, including diagnostic testing, do not lead to a definitive diagnosis.

This mixed-method study combines quantitative and qualitative approaches. A retrospective analysis of medical records will assess the proportion of fatigue consultations where diagnostics, ie. blood work, an EKG and an X-thorax, result in a somatic diagnosis. Additionally, qualitative interviews will provide insight into the experiences of patients who leave the consultation without a diagnosis. The interviews will have an open characters, based ons principles of "Grounded Theory" (a qualitative research approach that generates theories from data through iterative processes of coding, comparison, and analysis, rather than testing existing hypotheses)

The study will include adult patients referred to an internal medicine outpatient clinic for unexplained fatigue. Data collection will encompass both diagnostic outcomes and patient perceptions, with findings aimed at improving care pathways and diagnostic approaches for individuals with chronic fatigue.

The study will contribute to a deeper understanding of the diagnostic process for fatigue in secondary care and offer insights into the patient experience. This knowledge has the potential to enhance clinical practices and improve patient-centered care for individuals presenting with unexplained fatigue.

Cohort 1:

Inclusion Criteria:

• Patients under 18 years of age;
• Patients lost to follow-up.

Exclusion Criteria:

• Patients at the internal medicine outpatient clinic with a referral for fatigue e.c.i.
• Patients who visited the clinic after the 1st of April 2022.

Cohort 2:

Inclusion criteria

• Patients at the internal medicine outpatient clinic with a referral for fatigue e.c.i. whose consultation did not bring about a somatic diagnosis

Exclusion criteria:

• Patients under 18 years of age;
• Patients that do not speak Dutch fluently

Patients from the Almere region in Flevoland who visit Flevo Hospital Almere for a fatigue consultation. They speak Dutch and are over the age of 18. For the retrospective part of this study, the investigators will exclude patients who visited the clinic during the Covid period (before the 1st of April 2022).