Syndromal definitions and epidemiology of MUS
Insights and recognition of the prevalence, impact and the relativity of
the definitions used in current literature is an important prerequisite
for health care providers in their management of MUS. Indeed, the
prevalence of MUS is highly dependent on the case definitions used. All
definitions are syndromal and have the character of a checklist
approach. This is illustrated by the classification of a multi-setting
population of patients with MUS into either DSM IV somatization
(undifferentiated somatoform and pain) disorder versus DSM V somatic
symptom disorder (SDD) [6]. In a questionnaire study involving
baseline data of 325 MUS patients in 1st,
2nd and 3rd lines of health care,
DSM V SSD criteria proved more restrictive, as only 45.5 % fulfilled
these criteria while 92.9 % of participants were included using the DSM
IV criteria. DSM V SSD and the presence of psychologic criteria selected
for more symptom severity and physical dysfunction in MUS. With
chronification the semantic discussion remains, as exemplified in the
review of De Gucht et al. 2002, proposing a distinction into presenting
somatization secondary to psychological distress versus a primary
phenomenon characterized by the presence of MUS (functional
somatization). More recently, literature has moved away from this
labeling approach and focused on functional limitations and possibly on
different phenotypes that may be relevant for differential effects of
illness on disability. Furthermore there is considerable overlap between
the definitions of the different functional somatic syndromes [23,
24].
Whatever the limitations and the semantics of syndromal definitions,
patients frequently present in primary care with multiple somatic
complaints, that can be associated with significant distress and
functional impairment. These can become chronic in 20 to 25 % of cases,
associated with high use of medical services and increased risk of
iatrogenic complications [9]. In a point prevalence primary care
study, GP’s assessed presenting complaints as unexplained in 13 % of
consecutive at random consultations [35]. In a large scale
questionnaire survey of morbidity in 400.000 patients aged 18 years and
older and visiting their GP at least once a year in 104 general
practices in the Netherlands, 25-50 % of all reasons for a GP visit
concerned medically unexplained symptoms, 20 % of GP-patient contacts
physical symptoms without a pathological explanation. However, the
frequent presentation of such symptoms within the same individual is
significantly rarer: only 2.45 % presented at least 4 times in a single
year period with symptoms considered medically unexplained and lacking a
medical diagnosis. Socio-demographically these patients were
significantly older, more often female, less educated, more frequently
unemployed and more frequently of a non-Western origin than “average”
patients or patients with a medical diagnosis [36].
These patients also represent a considerable burden in acute care. In a
retrospective chart study of 2869 adult patients at three tertiary care
emergency departments (ED) MUS were present in 13.4 % of all ED
admissions, and in 18.5 % of patients, after exclusion of trauma.
Patients with MUS on the ED were more often younger, female,
self-referred and frequent visitors and more often had psychiatric
disease. Dutch and Belgian hospitals differed in the distribution of
patients in triage categories and the incidence of psychiatric
illnesses. Hence, patients with MUS represent a major burden to ED’s, as
in primary and secondary healthcare [2]. In an older retrospective
cohort study in secondary care, the proportion of MUS in frequent
attenders represented 54 % in gastroenterology, 50 % in neurology, 34
% in cardiology, 33 % in rheumatology, 30 % in orthopedic clinics, 27
% in otorhinolaryngology and even 17 % in general surgery and
gynecology and 15 % in pulmonary medicine [27]. Hence, they
represent a significant segment of medical activity and are
transversally relevant in most domains. A cross-sectional survey in two
London general hospitals estimated the prevalence and risk factors for
MUS across a variety of specialties; about half of the respondents from
seven outpatient clinics fulfilled criteria for MUS, representing the
most common diagnosis in some specialties with the highest prevalence in
the gynaecology clinic (66 %). After adjustment for confounders, MUS
were associated with female gender, younger age and current employment.
Psychiatric comorbidity was not associated per se with the presence of
MUS but was more likely in patients with multiple symptoms [23, 24].
In a review on somatization in refugees in non-Western countries
[29] the prevalence of somatization disorder was shown to be equal
in different refugee populations world-wide. The number of MUS is
generally higher among refugees as compared to non-refugees, but studies
are not comparable, as different definitions of somatization were used,
such as in clinical assessments and conclusions from questionnaires.
Somatization in refugees is strongly connected with psychopathology and
possibly with traumatization and with negative life events and might be
perceived as a specific idiom of distress, which accompanies PTSD.
Hence, refugee populations require specific screening for clinical PTSD.
Kounou et al, 2017 explored the relationship between peritraumatic
reactions, PTSD symptoms, somatization and quality of life in a
retrospective, cross-sectional study of a large sample of 101 adult
refugees (45 % of the female gender) 2 years after the 2011 Ivory Coast
sociopolitical crisis. They demonstrated that 86,1 % of participants
scored above the threshold for probable clinical PTSD. Peritraumatic
dissociation and stress were significantly associated with PTSD
symptoms. Somatization and PTSD symptoms negatively correlated with
quality of life. [19].