Factors associated with having previously received a diagnosis of fibromyalgia, chronic fatigue syndrome and irritable bowel syndrome: A cross sectional DanFunD study.

OBJECTIVES: Fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome are highly prevalent conditions and part of the functional somatic syndromes (FSS) diagnosis, that are classified under the unifying umbrella term functional somatic disorder (FSD). Multiple factors are associated with FSD symptom development; However, few studies have explored these associations in relation to the diagnosis status. This study aims to examine associations with a previously received FSS diagnosis from a physician in participants fulfilling the FSD diagnostic criteria in a population-based sample. METHODS: This research employs a comprehensive observational approach using a cross sectional design with data from the DanFunD part two cohort. Information about received FSS diagnoses was obtained from self-reported questionnaires. Participants fulfilling the FSD diagnostic criteria were identified with both self-reported questionnaires and diagnostic interviews. Validated questionnaires were used to assess the examined factors. RESULTS: 1704 cases fulfilled the diagnostic criteria for an FSD according to questionnaires or interviews in the DanFunD study. In participants fulfilling the diagnostic criteria, having previously received an FSS diagnosis by a physician was strongly associated with female sex, negative illness perceptions and poor health-related quality of life for questionnaire and interview-based diagnoses. Less consistent associations were observed for lower socioeconomic status, anxiety, and adverse life events. CONCLUSION: Previously received FSS diagnoses showed associations with multiple factors with a particular strong association with female sex and poor health related quality of life.

Efficacy of patient education and duloxetine, alone and in combination, for patients with multisystem functional somatic disorder: Study protocol for the EDULOX trial.

BACKGROUND: Multisystem functional somatic disorder is characterized by specific patterns of persistent physical symptoms with a complex biopsychosocial etiology. The disorder can lead to disability and personal suffering. Current treatment options require specialized settings, therefore patients often wait a long time to receive specific treatment. Patient education is considered important in most treatment programs, but has only been investigated sparsely as a stand-alone treatment. Pharmacological treatment is limited to tricyclic antidepressants in low doses with no antidepressant properties. Duloxetine has been found effective in single organ functional disorders. As a treatment for multisystem functional somatic disorder, duloxetine could reduce symptoms and treat comorbid anxiety and depression. It may furthermore enhance the effect of patient education through a hypothesized effect on cognitive functioning. The purpose of the EDULOX trial is to study psycho-EDUcation and duLOXetine alone and in combination. METHODS: This is a nested study design. The parent trial "EDULOX1" (n = 424) will compare a patient education program with enhanced usual care in an open-labelled, randomized controlled trial. In addition to this, eligible participants will furthermore receive either duloxetine or active placebo in the nested, double-blinded, randomized controlled trial, "EDULOX2" (n = 212). Patient and clinician reported outcomes will be collected through questionnaires. CONCLUSION: The EDULOX trial may establish evidence for treatments applicable for the majority of patients with multisystem functional somatic disorder. If effective, duloxetine would be a more tolerable pharmacological treatment option that can target comorbid depression and anxiety, and potentially boost the effect of patient education. Trial registration number The study is registered at www. CLINICALTRIALS: gov (NCT06232473) and the internal list of research projects at the Region of Central Denmark (Case number 1-16-02-305-23). Approval from the Danish Medical Research Ethics Committees (Case number: 2212291) and the Danish Medicines Agency was obtained under EudraCT Number: 2022-002780-30 and Sponsor's Protocol Code Number: 9515.

Hair cortisol and self-perceived stress in adolescents with multi-system functional somatic disorders.

BACKGROUND: Long-term stress causing altered hypothalamic-pituitary-adrenal (HPA) axis dynamics with cortisol dysfunction may be involved in the pathophysiology of functional somatic disorders (FSD), but studies on adolescents with multi-system FSD are lacking. Therefore, we investigated: 1) whether hair cortisol concentration (HCC) differentiates adolescents with multi-system FSD from a) a population-based sample and b) a subgroup derived from the sample reporting a high physical symptom load, and 2) whether FSD population HCC is associated with primary symptom presentations and self-perceived stress. METHODS: We used data from a clinical sample with multi-system FSD (N = 91, age 15-19 years) and a population-based sample (N = 1,450, age 16-17 years) including a subgroup with top 10% total scores on physical symptoms (N = 147). Density plots and multiple linear regression were applied to compare HCC between groups. In the clinical sample, multiple linear regression was employed to assess the association between HCC and primary symptom clusters and self-perceived stress. RESULTS: Median HCC was lower in the clinical sample than in the population-based sample (ß = 0.80 (95%CI: 0.66, 0.97)), but not significantly different from median HCC in the derived subgroup (ß = 0.84 (95%CI: 0.66, 1.07)). In the clinical sample, HCC was not significantly associated with primary symptom clusters (F(2, 82) = 0.13, p = 0.88) or self-perceived stress (F(4, 83) = 1.18, p = 0.33). CONCLUSION: Our findings indicate that HCC is lowered in adolescents with multi-system FSD but not significantly associated with primary symptom presentations or self-perceived stress. Future studies including multiple measures of HPA axis dynamics alongside psychological measures may further elucidate the role of long-term stress in FSD. TRIAL REGISTRATION: The AHEAD study was pre-registered at ClinicalTrials.gov (NCT02346071), 26/01/2015.

Neuroticism, perceived stress, adverse life events and self-efficacy as predictors of the development of functional somatic disorders: longitudinal population-based study (DanFunD).

BACKGROUND: Functional somatic disorder (FSD) is a unifying diagnosis that includes functional somatic syndromes such as irritable bowel, chronic widespread pain (CWP) and chronic fatigue. Several psychological factors are associated with FSD. However, longitudinal population-based studies elucidating the causal relationship are scarce. AIMS: To explore if neuroticism, perceived stress, adverse life events (ALEs) and self-efficacy can predict the development of FSD over a 5-year period. METHOD: A total of 4288 individuals who participated in the DanFunD baseline and 5-year follow-up investigations were included. FSD was established at both baseline and follow-up, with symptom questionnaires and diagnostic interviews. Neuroticism was measured with the short-form NEO Personality Inventory, perceived stress with the Cohen's Perceived Stress Scale, ALEs with the Danish version of the Cumulative Lifetime Adversity Measure and self-efficacy with the General Self-Efficacy Scale. Associations were investigated with multiple logistic regression models. RESULTS: Perceived stress predicted incident FSD, irritable bowel, CWP and chronic fatigue (odds ratios: 1.04-1.17). Neuroticism predicted incident FSD and chronic fatigue (odds ratios: 1.03-1.16). ALEs predicted incident FSD, CWP and chronic fatigue (odds ratios: 1.06-1.18). An increase in perceived stress from baseline to follow-up was associated with incident FSD, irritable bowel, CWP and chronic fatigue (odds ratios: 1.05-1.22). Contrary, an increase in self-efficacy seemed to be a protective factor (odds ratios: 0.89-0.99). CONCLUSIONS: High neuroticism, high perceived stress and a high number of ALEs are risk factors for the development of FSD. Particularly perceived stress seems to be an important contributor to the onset of FSD.

Self-help interventions for persistent physical symptoms: a systematic review of behaviour change components and their potential effects.

Persistent physical symptoms (PPS) remain a challenge in the healthcare system due to time-constrained consultations, uncertainty and limited specialised care capacity. Self-help interventions may be a cost-effective way to widen the access to treatment. As a foundation for future interventions, we aimed to describe intervention components and their potential effects in self-help interventions for PPS. A systematic literature search was made in PubMed, EMBASE, PsycINFO and CENTRAL. Fifty-one randomised controlled trials were included. Interventions were coded for effect on outcomes (standardised mean difference ≥0.2) related to symptom burden, anxiety, depression, quality of life, healthcare utilisation and sickness absence. The Behaviour Change Technique (BCT) Taxonomy v1 was used to code intervention components. An index of potential was calculated for each BCT within an outcome category. Each BCT was assessed as 'potentially effective' or 'not effective' based on a two-sided test for binomial random variables. Sixteen BCTs showed potential effect as treatment components. These BCTs represented the themes: goals and planning, feedback and monitoring, shaping knowledge, natural consequences, comparison of behaviour, associations, repetition and substitution, regulation, antecedents and identity. The results suggest that specific BCTs should be included in new PPS self-help interventions aiming to improve the patients' physical and mental health.

Measurement properties of the Health Anxiety by Proxy Scale (HAPYS): A new questionnaire to assess parents' worries about their child's health.

OBJECTIVE: Health anxiety by proxy refers to parents' excessive worries about their child's health. The Health Anxiety by Proxy scale (HAPYS) is a new self-report questionnaire to assess parents' worries and behaviors regarding their child's health. This study aimed to investigate the measurement properties of the HAPYS. METHODS: Questionnaires were completed by 204 parents, and a HAPYS score was obtained for 200 parents: 39 parents diagnosed with health anxiety, 33 parents with different anxiety disorders, 33 parents with a Functional Somatic Disorder, and 95 healthy parents. We evaluated the following measurement properties: structural validity, reliability, convergent validity ((pain catastrophizing, parents' reports of child's emotional and physical symptoms), discriminant validity (parental reports of child's well-being), and known-groups validity (see compared groups above). RESULTS: HAPYS demonstrated a one factor dimensionality, and excellent internal reliability (α = 0.95; CI: 0.93-0.97) and test-retest reliability after two weeks (ICC = 0.91; CI: 0.87-0.94). Convergent validity with the construct of parental catastrophizing about child pain was good (r = 0.72; CI: 0.64-0.78)). Good known-groups validity was demonstrated by the largest total HAPYS score observed in parents with health anxiety (median = 35; IQR: 9-53) and the lowest score in healthy parents (median = 9; IQR: 5-15) (p < 0.001). CONCLUSION: The findings support that HAPYS is a useful measure of health anxiety by proxy. Future research should examine the measurement properties in larger samples and different languages with further statistical analyses of structural validity.

Are Sexual Assaults Related to Functional Somatic Disorders? A Cross-Sectional Study.

An increasing number of sexual assaults (SAs) are being reported. This study investigated associations between SA and FSD, conceptualized as bodily distress syndrome (BDS), and five functional somatic syndromes (FSSs): chronic widespread pain (CWP), irritable bowel (IB), chronic fatigue (CF), multiple chemical sensitivity (MCS), and whiplash-associated disorder (WAD). Participants (n = 7493) from the population-based cohort Danish Study of Functional Disorders (DanFunD) completed questionnaires on FSD, emotional distress, SA, and sociodemographics. Risk ratios (RRs) for each FSD and emotional distress were calculated in nine models with SA as the primary exposure using generalized linear models with binomial family and log link and were adjusted for other potential risk factors. The results showed that SA was associated with single-organ FSD (RR = 1.51; 95% CI = 1.22-1.87), multi-organ FSD (RR = 3.51; 95% CI = 1.89-6.49), CWP (RR = 1.28; 95% CI = 0.83-1.98), IB (RR = 2.00; 95% CI = 1.30-3.07), CF (RR = 1.81; 95% CI = 1.42-2.32), WAD (RR = 2.62; 95% CI = 1.37-5.03), MCS (RR = 3.04; 95% CI = 1.79-5.17), emotional distress (RR = 1.75; 95% CI = 1.21-2.54), and health anxiety (RR = 1.65; 95% CI = 1.10-2.46). Overall, SA victims experienced significantly more somatic symptoms than individuals not exposed to SA. Adjusting for physical and emotional abuse did not change the observed associations. Our results suggest a large impact of SA on the overall somatic and mental health of SA victims. Due to the cross-sectional study design, further studies are required.

Examining associations between early adverse life events and health anxiety using the DanFund study.

Childhood adverse life events, in particular illness-related events, have been proposed as a risk factor for development of health anxiety. OBJECTIVE: To examine: 1) The association between accumulated early adverse life events and health anxiety in adulthood and 2) The influence of specific types of life events, i.e., illness, injury, loss, and the impact of their exposure time on health anxiety in adulthood. METHOD: A population-based, cross-sectional study including 7454 participants from the Danish study of Functional Disorders (DanFunD). Health anxiety was assessed with Whiteley-6-R and early adverse life events with the Cumulative Lifetime Adversity Measure. Caseness was defined as a Whiteley-6-R score ≥ 90%ile. Generalised linear models were used to estimate the association with relative risk (RRa, adjusted for sociodemographics). RESULTS: A cumulative effect was found for each additional adverse life event with 8.03% increased risk of health anxiety. Two categories were associated with a higher risk: violence (RRa = 1.65, 95% CI: 1.37-1.99, P < 0.001) and relationship stress (RRa = 1.34; 95% CI: 1.15-1.57, P < 0.001). Respondents with self-reported childhood illness were also more likely to report health anxiety (RRa = 1.52, 95% CI 1.11-2.09, P = 0.009). Timewise, health anxiety seemed associated with illness during school age and injury during adolescence. CONCLUSIONS: Accumulated adverse life events, early exposure to specific categories and specific health-related life events were associated with self-reported health anxiety in adulthood. Our findings provide new knowledge on the potential role of early life events in health anxiety which could inform early intervention.

Clinical Impact of Systematic Assessment and Psychoeducation in Specialized Treatment of Adolescents with Severe Functional Somatic Disorders: Results from the AHEAD Study.

Functional somatic disorders (FSD), characterized by persistent and disabling physical symptoms, are common in adolescents. Diagnostic uncertainty and insufficient illness explanations are proposed perpetuating factors that may constitute barriers for treatment engagement. This study describes the impact of manualized assessment and psychoeducation on diagnostic certainty and various clinical outcomes in adolescents with multi-system FSD. Ninety-one adolescents (15-19 years) received systematic assessment (4 h) and a subsequent psychiatric consultation (1.5 h). Clinical characteristics included self-reported physical health, symptom severity, illness perception, illness-related behavior, and psychological flexibility assessed before and approximately two months after assessment, prior to specialized treatment. Data were analyzed using t-tests. Immediately following assessment, 71 (80.7%) adolescents out of 88 reported a higher diagnostic certainty and 74 (84.1%) reported that attending assessment gave them positive expectations for future treatment. A clinically relevant improvement of physical health was not observed at two months but considerable reductions were seen in symptom severity, illness worry, negative illness perceptions, illness-related limiting behavior, and psychological inflexibility. The results emphasize that systematic assessment and psychoeducation are important in their own right in the specialized treatment of adolescents with severe FSD.

High Perceived Stress and Low Self-Efficacy are Associated with Functional Somatic Disorders: The DanFunD Study.

Objective: Several psychological factors have been proposed to be associated with functional somatic disorders (FSD) including functional somatic syndromes, such as irritable bowel, chronic widespread pain, and chronic fatigue. However, large randomly selected population-based studies of this association are sparse. This study aimed to investigate the association between FSD and perceived stress and self-efficacy, respectively, and to investigate if FSD differed from severe physical diseases on these aspects. Methods: This cross-sectional study included a random sample of the adult Danish population (n = 9656). FSD were established using self-reported questionnaires and diagnostic interviews. Perceived stress was measured with Cohen's Perceived Stress Scale and self-efficacy with the General Self-Efficacy Scale. Data were analysed with generalized linear models and linear regression models. Results: FSD were associated with higher perceived stress and lower self-efficacy, especially for the multi-organ and the general symptoms/fatigue FSD types and for chronic fatigue. However, controlling for the personality trait neuroticism altered the associations with self-efficacy so it became insignificant. The analysis did not support an important interaction between perceived stress and self-efficacy on the likelihood of having FSD. Individuals with FSD presented levels of perceived stress that were not equal, ie higher, to those in individuals with severe physical diseases. Conclusion: FSD were positively associated with perceived stress and negatively associated with self-efficacy. Our study may point to stress being part of the symptomatology of FSD. This underlines the severity of having FSD and stresses the relevance of the resilience theory in the understanding of the condition.

Internet-delivered treatment for patients suffering from severe functional somatic disorders: Protocol for a randomized controlled trial.

Background: Functional somatic disorders (FSDs) with symptoms from multiple organs, i.e., multi-system type, are common in the general population and may lead to disability and reduced quality of life. Evidence for efficient treatment programs has been established, however, there is a need for making treatments accessible to a larger group of patients. Internet-delivered therapy has become prevalent and has proven as effective as face-to-face therapy, while providing a flexible and easily accessible treatment alternative. The aim of the current study is to compare the efficacy of the therapist-assisted internet-delivered treatment program One step at a time (OneStep) with the internet-delivered self-help program Get started (GetStarted). Methods: A total of 166 participants aged 18-60 years diagnosed with multi-system FSD will be assessed and randomized to either 1) OneStep: a 14-week program consisting of 11 treatment modules based on principles from cognitive behavioural therapy or 2) GetStarted consisting of 1 module on psychoeducation. The primary outcome is physical health, assessed by a Short Form Health Survey (SF-36) aggregate score of the subscales vitality, physical functioning, and bodily pain 3 months after end-of-treatment and self-reported improvement assessed by the Clinical Global Improvement Scale. Secondary outcomes include symptom load, depression, anxiety, and illness worry. Process measures include emotional distress, illness perception, illness behaviour, and symptom interference. Conclusions: This study is the first study to test an internet-delivered treatment program for FSD, multi-system type and has the potential to show the importance of making evidence-based internet-delivered treatment for FSD more accessible.

Neuroticism and adverse life events are important determinants in functional somatic disorders: the DanFunD study.

Several psychological factors have been proposed to be associated with functional somatic disorders (FSD). However, large population-based studies investigating the importance of both personality and adverse life events (ALE) are sparse. This study aimed to investigate the association between FSD and neuroticism and the accumulated number of ALE, respectively. This cross-sectional study included a random sample of the adult Danish population (N = 7493). FSD were established by means of self-reported questionnaires and diagnostic interviews. Neuroticism was measured with the Danish version of the short-form NEO Personality Inventory. ALE were measured with the Danish version of the Cumulative Lifetime Adversity Measure. Strong positive associations were found between neuroticism and FSD, and ALE and questionnaire-based FSD. For interview-based FSD, strong positive associations were found for FSD, multi-organ type, and for the subtype of the general symptoms. The level of self-efficacy did not modify these associations, and no moderating effect of neuroticism and ALE in combination on the probability of having FSD was found. FSD were strongly associated with both neuroticism and the accumulated number of ALE, and these associations were not modified by self-efficacy. In combination, neuroticism and ALE did not have a moderating effect on the probability of having FSD.

Can the bodily distress syndrome (BDS) concept be used to assess functional somatic symptoms in adolescence?

OBJECTIVE: Bodily Distress Syndrome (BDS) represents a new research concept for adult patients with various functional somatic syndromes. We evaluated the utility of the BDS research concept and the associated BDS-25-checklist as a screening tool for diverse functional somatic symptoms (FSS) in adolescence by investigating: 1) the psychometric and factorial structures of the checklist, 2) symptom cluster patterns and 3) illness classification and associations with emotional psychopathology and sociodemographic factors. METHODS: This cross-sectional study obtained data from the 16/17-year follow-up (N = 2542) of the general population Copenhagen Child Cohort 2000 (CCC2000). We used self-reported questionnaires to assess physical symptoms (the BDS-25 checklist), overall health (KidScreen), emotional psychopathology (Spence Children's Anxiety Scale; The Mood and Feelings Questionnaire), and illness worry (Whiteley-6 Index), and utilized data from Danish national registers to assess sociodemographic factors. RESULTS: The BDS-25 checklist items displayed satisfactory psychometric data quality. Factor analyses revealed a similar four-factor model as reported in adults (factor loadings λ ≥0.5), representing distinct BDS symptom clusters: cardio-pulmonary, gastro-intestinal, musculoskeletal and general symptoms. Latent class analyses revealed a model with three latent classes, i.e. probable no to mild BDS, probable moderate, single-organ BDS and probable severe, multi-organ BDS, displaying acceptable class quality (Entropy = 0.904). Trend analyses revealed sociodemographic group differences across latent classes. Increased emotional psychopathology was associated with more pronounced BDS symptoms. CONCLUSION: Our findings support the BDS concept with four symptom clusters and three illness severity groups (no BDS, single- organ and multi-organ BDS) to screen for FSS in adolescence.

Development and Validation of the Weighted Index for Childhood Adverse Conditions (WICAC).

BACKGROUND: Adverse experiences in childhood are a major public health concern, promoting social inequality in health through biopsychosocial mechanisms. So far, no known measures comprehend the complexity and variations of severity of adverse events. This study aims to develop and validate a new index: the Weighted Index for Childhood Adverse Conditions (WICAC). METHODS: The population consists of 7493 randomly invited men and women aged 18-72 years. Data were collected in 2012-2015 as part of the Danish Study of Functional Disorders (DanFunD). Content and construct validation of the WICAC was performed with the hypothesis testing of multiple biopsychosocial outcomes: cardiovascular disease, cancer, poor health, back pain, BMI, obesity, anxiety, depression, low vitality, subjective social status, lower education, smoking, and alcohol consumption. Data were analysed with binominal and linear regression models with risk ratios (RR) and mean differences (MD). RESULTS: Content validation is fitting for WICAC. The strongest associations observed were for most severe adversity: Poor Health RR = 2.16 (1.19-2.91), Anxiety RR = 3.32 (2.32-4.74), Heavy Drinking RR = 4.09 (1.85-9.04), and Subjective Social Status MD = -0.481 (-0.721-(-0.241)). Similar results were found for the remaining outcomes. Discriminative validation was undecided. CONCLUSIONS: WICAC is an adequate instrument for measuring cumulative adverse life events in childhood and adolescence for research purposes.

Posttraumatic Stress Symptoms and Pain Sensitization After Whiplash Injury: A Longitudinal Cohort Study With Quantitative Sensory Testing.

Posttraumatic stress symptoms (PTSS) are common after whiplash injury and are associated with poor recovery. The acute stress response may lead to pain sensitization and widespread pain, thereby compromising recovery. To our knowledge, no longitudinal study has assessed the associations between early PTSS and pain sensitization over time using quantitative sensory testing (QST). The aim of this study was to compare participants with different levels of PTSS, as measured by the impact of event scale (IES; subclinical 0-8, mild 9-25, and clinical ≥ 26) at baseline (<10-day post-injury) and at a follow-up of 1, 3, 6, and 12-month post-injury on pain sensitivity, neck mobility, pain distribution, and pain intensity. In total, 740 participants were recruited from emergency units or general practitioners with acute neck pain after a whiplash injury. The clinical PTSS group showed increased pain sensitivity on all QSTs at all time points compared to the subclinical PTSS group. Also, the clinical PTSS group showed significantly lower neck mobility at all time points except for a 3-month follow-up compared to the subclinical PTSS group. Moreover, the clinical PTSS group showed more widespread pain and self-reported headache and neck pain intensity at all time points compared to the subclinical PTSS group. This study emphasizes that participants with clinical levels of PTSS constitute a high-risk group that is sensitized to pain early after the injury. Hence, screening for PTSS within the 1st week after whiplash injury for those who experience high levels of pain intensity and distress may be an important clinical procedure in the assessment and treatment of whiplash-associated disorders (WAD).

Are study populations in trials of antidepressants and psychotherapy comparable? A retrospective case study of two parallel running trials for multi- organ functional somatic disorder.

This study retrospectively compares two previous parallel running, randomized, controlled trials of pharmacotherapy (imipramine) and psychotherapy (acceptance and commitment therapy) for multi-organ functional somatic disorder (FSD). Differences in demographics, psychiatric comorbidity, illness severity, and illness duration associated with eligibility for the two trials and patients' willingness to participate are explored using linear or binary regression models. 418 patients with multi-organ FSD was included. We found that 377 (95%) were eligible for psychotherapy and 257 patients (61%) for pharmacotherapy. Patients eligible for pharmacotherapy were less severely impaired, less often received disability pension, reported shorter illness duration and experienced less psychological distress than patients eligible for psychotherapy. Whilst exclusion criteria for both trials differed markedly, it was not possible to clearly identify patient or illness characteristics associated with patients' willingness to participate. The study showed that trial-specific exclusion criteria led to the selection of less complex and less severely impaired patients in the pharmacological trial in this sample of multi-organ FSD. Our findings have important implications for the interpretation and comparability of RCT results of different treatments in multi-organ FSD and may point to some common flaws in study design and interpretation of pharmacological vs. psychotherapeutic intervention trials in psychiatry.

The impact of the Covid-19 pandemic on mental and physical health in Denmark - a longitudinal population-based study before and during the first wave.

BACKGROUND: In the continuation of the first wave of the Covid-19 outbreak in Denmark, unprecedented restrictions with great impact on the citizen's everyday life were implemented. The objectives of this study were to investigate the influence of the Covid-19 pandemic on mental and physical health in the Danish population during the spring 2020 first wave outbreak and lockdown. METHODS: A sample from the adult Danish population (n = 2190) were included. Self-reported measures of illness worry (Whiteley-6-R), emotional distress (SCL-90), and physical symptom load (SLC-90) were obtained before and during the first wave of the pandemic and compared with Wilcoxon signed-rank tests. Impact of covariates on physical and mental health was evaluated with ordinal regression analyses. Results from a tailored questionnaire regarding the Covid-19 pandemic were presented to explore the direct impact of the pandemic. RESULTS: We only found minor increases in illness worry, emotional distress and physical symptom load (0-1 points difference, p ≤ 0.007) during the Covid-19 pandemic compared to before the pandemic. Sex, age, education, and physical disease were not associated with illness worry, emotional distress, or physical symptom load. Overall, the participants were trustful in the authorities' recommendations and felt that they managed the pandemic and the restrictions to a great extent despite that some expected great/major future consequences of the pandemic. CONCLUSIONS: This study suggested that the first wave of the Covid-19 pandemic only had minor impact on mental and physical health in the Danish general population. Future studies should address the impact of the second wave of the pandemic and the renewed implementation of the concomitant restrictions.

Assessment of functional somatic disorders in epidemiological research: Self-report questionnaires versus diagnostic interviews.

OBJECTIVE: Self-reported symptom questionnaires are often used for identifying individuals with functional somatic disorders (FSD) in epidemiological research. Studies on their validity in establishing clinically valid cases are, however, lacking. We aimed to compare and dissect the processes of identifying participants with FSD with symptom questionnaires and FSD diagnoses established by diagnostic interviews. METHODS: Individuals from the adult Danish population (n = 1590) filled in symptom questionnaires and participated in a diagnostic research interview, performed over telephone by trained family physicians. The two methods were described and compared in different steps: 1) Agreement on presence of symptoms, 2) agreement after FSD symptom pattern criteria had been applied, and 3) agreement on final FSD diagnoses. RESULTS: Agreement on symptom presence was high (>82%). Using FSD symptom pattern criteria, the two methods agreed in 30-62% of cases within each category. Discrepancies were mainly due to participants fulfilling symptom patterns in the interview but not in the questionnaires. Agreement between final FSD questionnaire cases and final FSD interview diagnoses was moderate (>68%) with lower FSD prevalence in the interview (26.2% vs 44.5%). Discrepancies were largely explained by the interviewers assessing the symptom patterns to be caused by an alternative physical or mental condition. CONCLUSION: Prevalence of final FSD diagnoses were markedly lower in the diagnostic interview compared to self-reported questionnaires cases; mainly because of the clinical evaluation of symptom attribution and impairment. Symptom questionnaires may be valuable as screening tools and as trans-diagnostic comparison while diagnostic interviews are necessary in establishing clinically significant FSD diagnoses.

The BDS checklist as measure of illness severity: a cross-sectional cohort study in the Danish general population, primary care and specialised setting.

OBJECTIVE: The bodily distress syndrome (BDS) checklist has proven to be useful in the diagnostic categorisation and as screening tool for functional somatic disorders (FSD). This study aims to investigate whether the BDS checklist total sum score (0-100) can be used as a measure of physical symptom burden and FSD illness severity. DESIGN: Cross-sectional. SETTING: Danish general population, primary care and specialised clinical setting. PARTICIPANTS: A general population cohort (n=9656), a primary care cohort (n=2480) and a cohort of patients with multiorgan BDS from specialised clinical setting (n=492). OUTCOME MEASURES: All data were self-reported. Physical symptoms were measured with the 25-item BDS checklist. Overall self-perceived health was measured with one item from the 36-item Short-Form Health Survey (SF-36). Physical functioning was measured with an aggregate score of four items from the SF-36/SF-12 scales 'physical functioning', 'bodily pain' and 'vitality'. Emotional distress was measured with the mental distress subscale (SCL-8) from the Danish version of the Hopkins Symptom Checklist-90. Illness worry was measured with the six-item Whiteley Index. RESULTS: For all cohorts, bifactor models established that despite some multidimensionality the total sum score of the BDS checklist adequately reflected physical symptom burden and illness severity. The BDS checklist had acceptable convergent validity with measures of overall health (r=0.25-0.58), physical functioning (r=0.22-0.58), emotional distress (r=0.47-0.62) and illness worry (r=0.36-0.55). Acceptability was good with a low number of missing responses to items (<3%). Internal consistency was high (α ≥0.879). BDS score means varied and reflected symptom burden across cohorts (13.03-46.15). We provide normative data for the Danish general population. CONCLUSIONS: The BDS checklist total sum score can be used as a measure of symptom burden and FSD illness severity across settings. These findings establish the usefulness of the BDS checklist in clinics and in research, both as a diagnostic screening tool and as an instrument to assess illness severity.

Detection of illness worry in the general population: A specific item on illness rumination improves the Whiteley Index.

OBJECTIVE: The Whiteley Index (WI) is the most widely used screening tool for health anxiety/illness worry. Diverse versions (different number of items and factors) have been used. We aimed to examine psychometric properties of 7 items of the WI besides adding a new item on obsessive illness rumination for better future detection of health anxiety. METHODS: Data from a large population-based study in Denmark (N = 9656). Construct validity was examined by exploratory (EFA) and confirmatory factor analysis (CFA) plus hypothesis testing. Criterion validity was evaluated via Receiver Operating Characteristic curves and area under the curve (AUC) using a diagnostic criterion as gold standard. RESULTS: Factor loadings of EFA revealed viable one-factor models (6, 7, or 8 items) and two-factor models (7 or 8 items). Factor one indicated a dimension of illness worry. Factor two indicated a somatic symptoms dimension. The new item on obsessive illness rumination merged well with the existing items. EFA of two-factor models and one-factor 6-item model showed good fit. CFA resembles these findings. A one-factor 6-item model (including the item on obsessive illness rumination and excluding two items concerning somatic symptoms) was chosen as the optimal model and presented good criterion validity: AUC 0.88 (95%CI(0.84;0.92)). Main hypotheses concerning associations with somatic symptoms, anxiety, and depression were met. CONCLUSIONS: We found good psychometric properties for a new one-factor 6-item version of the WI. Through elimination of items concerning somatic symptoms and inclusion of obsessive illness rumination, we propose a clear, unidimensional and improved measure of illness worry: Whiteley-6-R.