General practitioners enrolled 856 patients, of whom 642 consented to participate and returned the baseline questionnaire (). All but 1 of these patients also consented to have data extracted from their general practitioner’s medical records. In addition, 15 patients who did not complete the baseline questionnaire consented to have data extracted from their medical records. We were able to obtain data on diagnoses for 571 (87.0%) of these 656 patients. Characteristics of the 571 participants are shown in .
Selection of participants and collection of data. *Includes 15 patients who did not complete any of the questionnaires but who consented to extraction of data.
Characteristics of 571 patients in primary care practices who presented with fatigue as a main symptom
Diagnoses made in the year following consultation represented all categories of the International Classification of Primary Care (ICPC).29,30
In total, 268 (46.9%) of the 571 patients received one or more diagnoses (378 in total) that could be associated with fatigue ().
Diagnoses during 1-year follow-up period among 571 patients in primary care practices who presented with fatigue as a main symptom
The most frequently recorded somatic diagnoses were musculoskeletal problems (n = 111 [19.4%]) and diseases or symptoms of the digestive system (n = 46 [8.1%]), nervous system (n = 38, [6.7%]) and respiratory tract (n = 28 [4.9%]). The majority of diagnoses reflected symptoms or signs only. A total of 47 patients (8.2%) received one or more diagnoses of clear somatic pathology (anemia, pulmonary pathology, thyroid dysfunction, diabetes mellitus, celiac disease, vitamin B12 deficiency, heart failure, angina pectoris, malignant disease, rheumatoid arthritis, adverse drug effect). Infections were diagnosed in 104 (18.2%) of the patients. When we considered the time frame from the onset of fatigue to the diagnosis of infection, infection was a likely explanation for the fatigue in 2 cases.
A total of 94 patients (16.5%) received a diagnosis indicating psychological problems or social difficulties. Stress or neurasthenia was the diagnosis most frequently recorded during the initial consultation ().
The frequency of psychological symptoms reported in the patient questionnaires differed from the frequency in the medical records. Overall, 155 (24.1%) of the 642 patients who completed a baseline questionnaire reported having depressive symptoms; this diagnosis was recorded in 28 (4.9%) of the 571 medical records that had diagnostic data. Distress or worry was reported by 392 (61.1%) of the patients but was recorded in 25 (4.4%) of the medical records. Sleep problems were reported by 417 (65.0%) of the patients but recorded in 11 (1.9%) of the patients’ charts (see also reference 29
Data on comorbidities were available for 539 of the patients. A total of 58 patients had a concurrent disease that could explain the fatigue. The most frequently recorded comorbid diseases were respiratory diseases (n = 37) and diabetes (n = 17). Fourteen patients were known to have a malignant disease in their medical history. For 20 patients, a functional syndrome, most often irritable bowel syndrome, had been recorded in their chart.
The participants in our study received a wide range of diagnoses in the year following consultation that could have been associated with the fatigue. Psychological and physical problems were diagnosed more frequently than somatic diseases. The variety of diagnoses reflects evidence from the literature and practical experience regarding the differential diagnosis of fatigue.
The small proportion of patients who received a diagnosis of somatic pathology corresponds with findings of previously published smaller studies in primary care.24,25,32
Those studies, however, used stricter inclusion criteria, excluded patients with existing chronic disease or reported on diagnoses based only on laboratory test results. Two studies, one of which included only 52 patients, reported higher prevalence rates of somatic disease (45% and 51%) than in our study.22,33
Of chronic diseases that were likely to be present at the time of consultation, respiratory conditions were more frequent in our cohort than in the general patient population in primary care in the Netherlands.15
Our study population had fewer older patients compared with those in a Dutch national morbidity registry,34
which may explain the difference in prevalence of chronic respiratory conditions.
Of the patients in our study who received a symptom diagnosis during the follow-up year, one-fifth received a diagnosis of a musculoskeletal problem, mostly nonspecific. Virtually none of the symptom diagnoses were established during the consultation, which raises questions about the temporal association between fatigue and other symptoms. Because most symptoms may show a recurrent pattern over time, further research is needed to help clarify the association between fatigue and other nonspecific symptoms.
Although psychological or social problems were the second largest diagnostic category, the number may be an underestimation. Depressive symptoms and elevated distress scores were reported more frequently in the patient questionnaires than in the medical records. Furthermore, other studies have reported psychological symptoms in the majority of patients with fatigue.35–37
Because of the variation in how the general practitioners recorded or coded the diagnoses, psychological problems may have been identified but not explicitly recorded as diagnoses in the patients’ charts.
Sleep problems were recorded in only 1.9% of the patients’ charts. This number is in stark contrast to the number of sleep problems reported by the majority of patients in the questionnaires. As with psychological symptoms, problems with sleep might either not be recognized or not recorded.38–40
Because general practitioners may perceive a sleep problem as a lifestyle issue or evidently related to fatigue, they may not record it as a diagnosis.
At least half of the patients did not receive a diagnosis that could possibly explain their fatigue. This suggests that fatigue remains “medically unexplained” in many cases, which is consistent with previous findings.21
However, the lack of a medical explanation does not always mean that there is no explanation. Given the data in the questionnaires, other psychosocial factors, although not registered in the patients’ medical records, may have played a role in the fatigue of many patients.
Almost 50% of the patients did receive a diagnosis in the year following consultation that could explain their fatigue. However, for most of the diagnoses, we were unable to assess the potential association with fatigue more closely, even when considering the time frame from onset of the fatigue to the diagnosis. This would require more information both on the severity of the symptom or disorder diagnosed and on the severity of the fatigue at the time of diagnosis.
One limitation of our study was that we did not use a standardized protocol for physical examination or diagnostic testing. The diagnoses represent those made and recorded in daily practice by individual general practitioners. Because general practitioners differ in their decision-making regarding diagnostic procedures and referrals, this will have resulted in variation in recorded diagnoses.
Data on existing comorbidities are important to provide when presenting an overview of diagnoses. We were able to show that respiratory conditions and diabetes were more often pre-existing than newly diagnosed conditions. Our data were not comprehensive, however, and we may have missed other conditions that could have been associated with the fatigue. Furthermore, patients presenting with fatigue may have several concurrent conditions.
The patients who presented with fatigue in primary care had a wide range of diagnoses. However, the prevalence of severe pathology was low. The number of psychosocial problems was relatively high and may explain in part the fatigue in this primary care population. In addition, the number of psychosocial symptoms, including sleep problems, differed between the patients’ medical records and the self-reported data from the questionnaires. Practitioners need to address these problems in patients presenting with fatigue.