An exploratory study comparing psychological profiles and its congruence with clinical performance among patients with functional or motility digestive disorders

Abstract

Functional gastrointestinal disorders have been related with different psychological conditions. On the contrary, the role of psychological factors within gastrointestinal motor disorders remains unclear. The objective of this study was to explore the differences and congruence with clinical performance of the psychological profile and subjective functionality among patients diagnosed with functional gastrointestinal disorders and gastrointestinal motor disorders. Using a double-blind design, 56 inpatients from a Gastroenterology Department were included in the study. No major differences were detected between the two groups. However, clinical performance was coherent with subjective physical functioning only among patients diagnosed with gastrointestinal motor disorders. These results may provide useful information for gastroenterologists dealing with patients’ complaints not consistent with their clinical profile.

Keywords

clinical performance congruence functional gastrointestinal disorders gastrointestinal motility disorders subjective functionality

Introduction

Some patients complain of severe digestive symptoms in the absence of organic causes. Symptoms include abdominal discomfort and/or pain, abdominal distension and inability to consume regular meals. From a gastroenterological point of view, two main diagnostic categories are distinguished: patients in whom a motor dysfunction of the gut can be evidenced by objective criteria (i.e. abnormal motility) classified as gastrointestinal motor disorder (GMDs) and those without objective dysfunction. The clinical manifestations in both categories may be indistinguishable, and the distinction in the most severe cases requires functional tests such as intestinal manometry. Patients without demonstrable GMDs are diagnosed with functional gastrointestinal disorders (FGDs, Drossman, 2006). Different functional gastrointestinal syndromes have been defined based on clinical criteria. They include irritable bowel syndrome (IBS; abdominal pain or discomfort associated with changes in bowel habit), functional dyspepsia (symptoms thought to be originated in the gastro-duodenal region; in the absence of any organic, systemic or metabolic disease likely to explain these symptoms) and rumination (persistent or recurrent regurgitation of recently ingested food into the mouth with subsequent spitting or re-mastication and swallowing, in the absence of structural disease). The causes of FGDs are still unknown; hence, functional stands actually for idiopathic. Experimental data suggest that FGD symptoms are related to subtle sensory and reflex dysfunctions of the gut that are not detectable by conventional methodologies, leading to reduced tolerance of physiological stimuli in the gut.

Moreover, there is evidence that the development of symptoms is the result of interactions between somatic, psychological and social factors with high interpersonal variability (Bennett et al., 1998). They are often associated with psychological distress (Koloski et al., 2003), personality characteristics (Fava et al., 2007), child abuse (Lackner et al., 2006) and sociocultural issues mainly related to lifestyles, gender and explanatory models of the disorder among patients and physicians (Chang et al., 2006). Furthermore, epidemiological data points to the presence of psychiatric comorbidities in 40–60 per cent of patients diagnosed with FGDs (Levy et al., 2006). It has been suggested that people suffering FGDs, but not seeking medical advice, have a similar psychological profile to asymptomatic individuals (Drossman et al., 1999). On the contrary, patients with a FGD demanding medical specialized care have more anxiety, depression, health-related anxiety and hypochondriac symptoms and are less likely to link distress with their symptoms, compared to people not consulting or remaining in primary care (Guthrie et al., 2003; Heaton et al., 1992; Whitehead et al., 1988). Likewise, some recent studies show similar results in community and primary care settings, suggesting a direct relationship between psychological co-morbidity and FGDs, rather than a biased observations in referral centres (Wu, 2012).

While FGDs have been widely studied from a psychological perspective, often showing the presence of diverse symptomatology (Bennett et al., 1998; Drossman et al., 1999; Heaton et al., 1992; Whitehead et al., 1988; Wu, 2012), GMDs have received less attention from the behavioural sciences. This can be explained as these disorders are evidenced by a structural disease to justify it. However, some studies point out to psychiatric illness causing gastric dysmotility (Peupelmann et al., 2009; Quick et al., 2010; Ruhland et al., 2008). In addition, anxiety and depression levels have been associated with gastroparesis severity and hospitalizations but not with disease aetiology or degree of gastric retention in a wide sample of gastroparesis patients (Hasler et al., 2010).

However, despite all this evidence, the differences between GMDs and FGDs have not still been explored in the context of specialized tertiary care, where the most severe cases are typically treated. For all these reasons, the aim of this study was to compare the psychological, subjective functionality and clinical-assessed performance profiles of patients admitted for specialized assessment in an inpatient tertiary Digestive Unit.

Methods

Participants

During 1 year, all patients hospitalized for evaluation of gastrointestinal motor function in a highly specialized Digestive Unit based at a tertiary referral centre, were included in this study. Patients had been referred because of suspected gastrointestinal motor abnormality and organic lesions. Mechanical obstruction had been ruled out by a thorough work-up before inclusion in the study. The protocol of the study was approved by the Ethics Committee of the University Hospital Vall d’Hebron and all participants gave their written informed consent.

Clinical assessment

All patients underwent gastrointestinal and psychiatric evaluation. Among patients not fulfilling criteria of intestinal dysmotility, those with clinical symptoms compatible with gastroparesis underwent gastric emptying and gastric tone evaluation. Patients without objective evidence of motor disorder (inability, pseudo-obstruction or gastroparesis) were evaluated using Rome III criteria to establish a FGD diagnosis.

Regarding psychiatric and psychological assessment, a clinical interview and a battery of psychometric tests was administered in the first 72 hours after hospital admission. All the semi-structured interviews were carried out by the same psychiatrist (who was completely blind to patients’ digestive diagnosis or any previous clinical information), covering main psychopathological domains according to the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I; First et al., 1997) and Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II; Firstet al., 1997) based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000). The selection of questionnaires was done according to the basic psychometric evaluation protocol of the hospital’s liaison psychiatry service, including perceived functionality, depression and anxiety, general psychopathology and personality traits. Additionally, the assessment of alexithymia was introduced, given the findings in studies reporting the increased presence of this trait in patients diagnosed with FGDs (Mazaheri et al., 2012; Porcelli et al., 2004, 2014). The following battery of self-administered questionnaires was included:

Self-perceived functionality. The Short-Form Health Survey (SF-36; Ware and Sherbourne Donald, 1992) was used to measure subjective physical and social functionalities.

Psychopathology. The Toronto Alex-ithymia Scale (TAS-20; Martínez-Sánchez, 1996; Taylor et al., 1988) was used to assess alexithymia, defined as an inability to identify and describe emotions in the self (Sifneos, 1973); the Hospital Anxiety and Depression Scale (HAD; Zigmond and Snaith, 1983) to assess anxiety and depression; the Symptom Checklist-90–Revised (SCL-90-R; Derogatis, 1994) as a multidimensional measure of general psychopathology (including somatization, obsessive–compulsive disorder, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation and psychoticism domains).

Personality traits. The Revised Neuroticism-Extroversion-Openness–Five-Factor Inventory (NEO-FFI-R; McCrae and Costa, 2004) was used for the assessment of personality traits including extraversion, agreeableness, conscientiousness, neuroticism and openness to experience.

Physical assessment. Clinical functional impairment was assessed with the Karnofsky Performance Status (KPS; Karnofsky and Burchenal, 1949) Scale. This clinician-administered scale covers a range from 0 (death) to 100 (perfect health). Although it was initially designed to be used with patients diagnosed with cancer, its use has been extended to other medical conditions including digestive disorders (Borgaonkar, 2000).

Statistical analyses

Non parametric statistics were used to compare sociodemographic characteristics and psychological measures between groups. Categorical variables were compared between groups using chi-square tests. Continuous variables were compared using Mann–Whitney–Wilcoxon rank-sum test for independent variables with two levels and Kruskal–Wallis H test for independent variables with three levels. Spearman’s rho, a non-parametric statistic, was used to correlate clinical performance with subjective functioning, psychopathology and personality traits. In the case of multiple comparisons, Bonferroni adjustment was used to correct the alpha level.

Results

During the one-year period, 56 patients were enrolled in the study (see Figure 1). Four patients were excluded from the study after psychiatric and digestive assessment, as they did not meet criteria for neither a FGD nor a GMD (two met criteria for anorexia nervosa, one for a cluster C personality disorder and the last one did not fulfil any psychiatric or digestive diagnosis). Based on gastrointestinal function tests (intestinal manometry and gastric emptying), patients were classified in two subgroups: 17 patients were diagnosed with GMDs (7 inability, 2 gastroparesis and 8 chronic intestinal pseudo-obstruction) and the rest (35 patients in which no objective evidence was found) were diagnosed with FGDs (10 functional dyspepsia, 18 IBS and 7 rumination).

Figure 1.

Flow diagram of the study.

Sociodemographic and psychosocial characteristics

Sociodemographic and psychosocial characteristics are shown in Table 1. Patients with objective criteria of gastrointestinal motor dysfunction were younger than those without (i.e. patients diagnosed of FGDs), although no statistical significant differences were found. Differences were neither found in the distribution of gender, education, professional activity, marital status or family dynamics.

Table 1.

Sociodemographic and psychosocial characteristics of the sample.

	FGD (n = 28)		GMD (n = 17)		Significance between FGD and GMD
	M	SD	M	SD	Significance between FGD and GMD
Age (M ± SD)	41.94	±14.28	35.76	±14.83	(z = −1.747, p = .081)
	N	%	N	%
Sex (% females)	30	85.7	13	76.5	(χ² = .683, p = .409)
Education
Primary	14	40	5	29.4	(χ² = .794, p = .672)
Secondary	14	40	7	41.2
Higher	7	20	5	29.4
Professionally active (%)*	24	68.6	13	76.5	(χ² = .348, p = .555)
Marital status**
Married/stable couple	23	65.7	9	52.9	(χ² = .686, p = .408)
Alone	12	34.3	8	47.1	(χ² = .686, p = .408)
Family dynamics (% normal)^a	23	65.7	14	82.4	(χ² = 1.543, p = .214)

M: Mean; SD: standard deviation; FGD: functional gastrointestinal disorders (functional dyspepsia and irritable bowel syndrome); GMD: gastrointestinal motility disorders (chronic intestinal pseudo-obstruction, gastroparesis and inability).

Family dynamics: not normal denotes problems with their primary support group, as defined by the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev., Axis IV criteria; American Psychiatric Association, 2000).

These categories were collapsed because of low n as follows:

Any work activity or housekeeping.

Alone includes single, divorced and widow.

Psychometric scales

Psychometric variables are shown in Table 2. Patients with GMDs performed better (higher scores) in SF-36 Physical Role (z = 2.186, p = .029), but not in other SF-36 subscales. No statistically significant differences were found in depression (HAD), anxiety (HAD), alexithymia (TAS-20), general psychopathology (SCL-90), personality traits (NEO-FFI-R) or clinical severity (KPS).

Table 2.

Psychometric tests among different diagnosis (means ± standard deviations).

Psychometric test	FGD	GMD	Significance FGD vs GMD
SF-36 (T scores)
Physical Functioning	39.68 ± 12.90	40.79 ± 14.40	(z = −.539, p = .590)
Physical Role	33.90 ± 10.52	38.50 ± 11.93	(z = −2.186, p = .029)
Pain	34.14 ± 9.82	36.64 ± 9.49	(z = −1.309, p = .191)
General Health	36.82 ± 10.09	35.50 ± 8.18	(z = −.659, p = .510)
Vitality	37.64 ± 10.44	38.36 ± 10.02	(z = −.192, p = .848)
Social Functioning	29.30 ± 14.30	33.86 ± 13.10	(z = −1.772, p = .076)
Emotional Role	43.44 ± 14.40	42.21 ± 15.23	(z = −.529, p = .597)
Emotional Well-Being	42.22 ± 11.93	43.57 ± 12.61	(z = −.036, p = .971)
TAS	46.16 ± 13.91	48.43 ± 17.15	(z = −.633, p = .527)
HAD depression	5.18 ± 4.16	5.07 ± 4.58	(z = −.096, p = .924)
HAD anxiety	7.80 ± 5.15	7.86 ± 5.82	(z = −.347, p = .729)
SCL-90-R (T scores)
Somatization	62.90 ± 8.44	61.58 ± 8.83	(z = −.527, p = .598)
Obsessive–compulsive	55.61 ± 13.75	53.42 ± 15.57	(z = −.442, p = .659)
Interpersonal sensitivity	52.61 ± 14.13	52.17 ± 13.87	(z = −.016, p = .987)
Depression	59.76 ± 14.76	58.83 ± 13.28	(z = −.278, p = .781)
Anxiety	59.24 ± 13.73	55.50 ± 15.35	(z = −.555, p = .579)
Hostility	51.07 ± 13.00	53.08 ± 13.56	(z = −.696, p = .486)
Phobic anxiety	51.80 ± 15.72	48.25 ± 16.02	(z = −.678, p = .498)
Paranoid ideation	51.02 ± 15.91	46.83 ± 13.71	(z = −.844, p = .399)
Psychoticism	57.78 ± 13.63	56.17 ± 15.43	(z = −.361, p = .718)
NEO-FFI-R (T scores)
Neuroticism	49.20 ± 12.73	51.21 ± 13.47	(z = −.932, p = .352)
Extraversion	47.71 ± 9.83	47.86 ± 9.82	(z = −.323, p = .747)
Openness to Experience	52.16 ± 9.85	51.79 ± 8.71	(z = −.587, p = .557)
Agreeableness	51.53 ± 10.42	47.57 ± 13.10	(z = −.1.449, p = .147)
Conscientiousness	54.00 ± 8.92	52.79 ± 7.51	(z = −.743, p = .458)
KPS	68.43 ± 16.17	64.12 ± 20.15	(z = −.832, p = .405)

FGD: functional gastrointestinal disorders (functional dyspepsia and irritable bowel syndrome); GMD: gastrointestinal motility disorders (chronic intestinal pseudo-obstruction, gastroparesis and inability); SF: Short-Form Health Survey; TAS: Toronto Alexithymia Scale; HAD: Hospital Anxiety and Depression Scale; SCL-90-R: Symptom Checklist-90–Revised; NEO-FFI-R: Revised Neuroticism-Extroversion-Openness–Five-Factor Inventory; KPS: Karnofsky Performance Status.

Regarding sub-diagnoses, no statistically significant differences were found between GMD subgroups (we compared a group of inability or gastroparesis with chronic intestinal pseudo-obstruction using Mann–Whitney U tests) regarding any psychometric measure. On the contrary, among patients diagnosed of FGDs (we compared functional dyspepsia, IBS and 7 rumination using Kruskal–Wallis H tests), those with rumination had higher scores in the SF-36 Physical Functioning (χ² = 7.474, p = .024), NEO-FFI-R Agreeableness (χ² = 5.843, p = .050) and Conscientiousness (χ² = 6.40, p = .044) scores, compared to patients diagnosed with functional dyspepsia and IBS. No difference remained statistically significant after Bonferroni adjustment (.05/26 = .002).

Correlation between clinician-assessed performance and subjective functionality

The correlation between clinician (KPS) and patient’s assessments of functionality (SF-36 subscales), and the rest of the psychometric measures in both groups, showed statistical significant correlations for SF-36 Physical Functioning (ρ = .378, p = .010), NEO-FFI Extraversion (ρ = .313, p = .034) and NEO-FFI Conscientiousness (ρ = .323, p = .028). Partial correlations controlling for diagnosis showed statistical significant correlations for SF-36 Physical Functioning (r = .438, p = .003). When stratifying the analysis, patients with GMDs had statistically significant correlations with SF-36 Physical Functioning (ρ = .752, p = .002) and SF-36 Physical Role (ρ = .540, p = .046), while FGDs’ scores did not reach statistical significance for any correlation. For a graphical representation of the correlation of the KPS with SF-36 Physical Functioning, including 95 per cent confidence intervals, see Figure 2.

Figure 2.

Scatter plots showing the correlation of clinical performance and subjective functionality of patients diagnosed with FGDs (up) and GMDs (down).

Discussion

Our results show that among patients with severe symptoms assessed in tertiary care, those diagnosed with FGDs have a similar psychological profile and illness severity to those diagnosed with GMDs. However, despite this similarity, clinician-rated severity was not consistent with the subjective perception of functionality, in the case of patients diagnosed with FGDs.

This is the first study comparing different psychological and psychopathological variables between GMDs and FGDs in a detailed way. Additionally, psychometric and psychiatric assessment was done blind to digestive diagnosis. Our results focused on the relation between clinician-rated performance, patient-perceived functionality and other psychometric measures including alexithymia, depression, anxiety, general psychopathology and personality traits. On one hand, differences between FGDs and GMDs were only found for the SF-36-Physical Role subscale. On the other hand, clinician-rated severity correlated with subjective functionality just in the case of patients diagnosed with GMDs, showing a lack of coherence between clinician-rated severity and perceived functionality for FGD-diagnosed patients.

The scores in psychometric measures, even among patient-rated functionality scores (SF-36), were similar in both groups. This similarity may be explained in the context of a tertiary referral centre, where patients diagnosed with GMDs and FGDs have an equivalent clinician-rated severity. It should be kept in mind that patients diagnosed with FGDs included in this study have a more severe clinical picture than those usually found in the general population or in primary care (Koloski et al., 2003; Okumura et al., 2010). Although patients with FGDs have been found to have higher levels of neuroticism, distress and anxiety compared with the general population in previous studies, these traits have not been found to differentiate patients consulting with those who do not (Koloski et al., 2002).

Incongruence of self-reported versus clinician-reported measures of functionality or severity can be seldom found in the medical literature (Cowen et al., 2007; Elser and Fantl, 1995; Schrader, 1997), but are rarely explored more in depth. To our knowledge, it is the first time this topic is analysed among patients with gastrointestinal pathologies. On one hand, patients diagnosed with GMD would seem ‘coherent’ with what is expected of them. Patients with more severe clinical pictures, including eating limitations or nasogastric tubes, would have consistent physical functioning problems. On the other hand, some patients diagnosed with FGDs report levels of functionality inconsistent with what clinicians would expect from them. We may approach these results in two ways. First, we may appeal to the supposed objectivity of clinical judgment. From this point of view, these patients would be perceiving levels of functionality below what they are ‘really’ capable of. However, this may also have to do with a clash of clinician’s and patient’s expectations. Clinicians’ may find clinical complaints to be not consistent with their exploration, while patients might attribute these symptoms to the gastric disease. This leads us to believe that more studies in the future should study in-depth factors causing inconsistencies between self-reported and hetero-reported clinical data.

Several limitations of the study should also be noted. On one hand, given the low prevalence of GMDs, the sample was too small to deepen in the determinants of the incongruence between subjective and clinician-assessed functionality. On the other hand, these patients have very severe conditions. For this reason, they are derived to a highly specialized unit in a tertiary referral centre. Hence, our data cannot be generalized to primary care patients or the general population.

Despite these limitations, the results of this study may allow the medical community to think about future projects that could further investigate the determinants of the congruence between clinician-reported measures and self-perceived functionality in patients diagnosed with digestive disorders. With respect to this line of research, more studies will be needed to check for different profiles within both diagnostic groups that could explain the inconsistency of subjective with clinician-assessed functionality.

Footnotes

Acknowledgements

The first and the second authors contributed equally to the development, analysis and report of this study. The authors would like to thank all the clinical staff and patients who were involved in this study.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Research Institute of the University Hospital Vall d’Hebron (VHIR), Barcelona, Spain.

References

American Psychiatric Association (2000) Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (4th edn). Text revision. Washington, DC: American Psychiatric Publishing, p. 943.

Bennett

Piesse

Palmer

. (1998) Functional gastrointestinal disorders: Psychological, social, and somatic features. Gut 42(3): 414–420.

Borgaonkar

(2000) Quality of life measurement in gastrointestinal and liver disorders. Gut 47(3): 444–454. DOI: 10.1136/gut.47.3.444.

Chang

Toner

Fukudo

. (2006) Gender, age, society, culture, and the patient’s perspective in the functional gastrointestinal disorders. Gastroenterology 130(5): 1435–1446. DOI: 10.1053/j.gastro.2005.09.071.

Cowen

Wakefield

Cloutier

(2007) Classifying asthma severity: Objective versus subjective measures. Journal of Asthma 44(9): 711–715. DOI: 10.1080/0277 0900701595576.

Derogatis

(1994) SCL-90-R: Administration, Scoring and Procedures Manual (3rd edn). Baltimore, MD: Clinical Psychometric Research.

Drossman

(2006) Rome III: The functional gastrointestinal disorders. Gastroenterology 130(5): 1377–1390.

Drossman

Creed

Olden

. (1999) Psychosocial aspects of the functional gastrointestinal disorders. Gut 45(Suppl. 2): II25–II30.

Elser

Fantl

(1995) Comparison of ‘subjective’ and ‘objective’ measures of severity of urinary incontinence in women. Neurourology and Urodynamics 14(4): 311–316. DOI: 10.1002/nau.1930140403.

10.

Fava

Fabbri

Sirri

. (2007) Psychological factors affecting medical condition: A new proposal for DSM-V. Psychosomatics 48(2): 103–111.

11.

First

Gibbon

Spitzer

(1997) Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II). Arlington, VA: American Psychiatric Press, Inc.

12.

First

Spitzer

Gibbon

. (1997) Structured Clinical Interview for DSM-IV Axis I Disorders: Clinician Version (SCID-CV). Arlington, VA: American Psychiatric Press, Inc., p. 132.

13.

Guthrie

Creed

Fernandes

. (2003) Cluster analysis of symptoms and health seeking behaviour differentiates subgroups of patients with severe irritable bowel syndrome. Gut 52(11): 1616–1622.

14.

Hasler

Parkman

Wilson

. (2010) Psychological dysfunction is associated with symptom severity but not disease etiology or degree of gastric retention in patients with gastroparesis. American Journal of Gastroenterology 105(11): 2357–2367. DOI: 10.1038/ajg.2010.253.

15.

Heaton

O’Donnell

Braddon

. (1992) Symptoms of irritable bowel syndrome in a British urban community: Consulters and nonconsulters. Gastroenterology 102(6): 1962–1967.

16.

Karnofsky

Burchenal

(1949) The clinical evaluation of chemotherapeutic agents in cancer. In: MacLeod

(ed.) Evaluation of Chemotherapeutic Agents. New York: Columbia University Press, p. 196.

17.

Koloski

Talley

Boyce

(2002) Epidemiology and health care seeking in the functional GI disorders: A population-based study. American Journal of Gastroenterology 97(9): 2290–2299.

18.

Koloski

Talley

Boyce

(2003) Does psychological distress modulate functional gastrointestinal symptoms and health care seeking? A prospective, community Cohort study. American Journal of Gastroenterology 98(4): 789–797. DOI: 10.1111/j.1572-0241.2003.07388.x.

19.

Lackner

Gudleski

Zack

. (2006) Measuring health-related quality of life in patients with irritable bowel syndrome: Can less be more? Psychosomatic Medicine 68(2): 312–320. DOI: 10.1097/01.psy.0000204897. 25745.7c.

20.

Levy

Olden

Naliboff

. (2006) Psychosocial aspects of the functional gastrointestinal disorders. Gastroenterology 130(5): 1447–1458. DOI: 10.1053/j.gastro.2005.11.057.

21.

McCrae

Costa

Jr (2004) A contemplated revision of the NEO Five-Factor Inventory. Personality and Individual Differences 36(3): 587–596.

22.

Martínez-Sánchez

(1996) Adaptación española de la Escala de Alexitimia de Toronto (TAS-20). Clinica y Salud 7(1): 19–32.

23.

Mazaheri

Afshar

Weinland

. (2012) Alexithymia and functional gastrointestinal disorders (FGID). Medicinski Arhiv 66(1): 28–32.

24.

Okumura

Tanno

Ohhira

. (2010) Prevalence of functional dyspepsia in an outpatient clinic with primary care physicians in Japan. Journal of Gastroenterology 45(2): 187–194.

25.

Peupelmann

Quick

Berger

. (2009) Linear and non-linear measures indicate gastric dysmotility in patients suffering from acute schizophrenia. Progress in Neuro-Psychopharmacology and Biological Psychiatry 33(7): 1236–1240. DOI: 10.1016/j.pnpbp.2009. 07.007.

26.

Porcelli

Affatati

Bellomo

. (2004) Alexithymia and psychopathology in patients with psychiatric and functional gastrointestinal disorders. Psychotherapy and Psychosomatics 73: 84–91. DOI: 10.1159/000075539.

27.

Porcelli

De Carne

Leandro

(2014) Alexithymia and gastrointestinal-specific anxiety in moderate to severe irritable bowel syndrome. Comprehensive Psychiatry 55(7): 1647–1653. DOI: 10.1016/j.comppsych.2014.05.022.

28.

Quick

Kliem

Berger

. (2010) Gastric dysmotility in major depression. Progress in Neuro-Psychopharmacology and Biological Psychiatry 34(1): 92–97. DOI: 10.1016/ j.pnpbp.2009.10.003.

29.

Ruhland

Koschke

Greiner

. (2008) Gastric dysmotility in patients with major depression. Journal of Affective Disorders 110(1–2): 185–190. DOI: 10.1016/j.jad.2007.12.236.

30.

Schrader

(1997) Subjective and objective assessments of medical comorbidity in chronic depression. Psychotherapy and Psychosomatics 66(5): 258–260. DOI: 10.1159/000289144.

31.

Sifneos

(1973) The prevalence of ‘Alexithymic’ characteristics in psychosomatic patients. Psychotherapy and Psychosomatics 22(2–6): 255–262. DOI: 10.1159/000286529.

32.

Taylor

Bagby

Ryan

. (1988) Criterion validity of the Toronto Alexithymia Scale. Psychosomatic Medicine 50(5): 500–509.

33.

Ware

Jr Sherbourne Donald

(1992) The MOS 36-item short-form health survey (SF-36). I: Conceptual framework and item selection. Medical Care 30(6): 473–483.

34.

Whitehead

Bosmajian

Zonderman

. (1988) Symptoms of psychologic distress associated with irritable bowel syndrome. Comparison of community and medical clinic samples. Gastroenterology 95(3): 709–714.

35.

(2012) Psychological co-morbidity in functional gastrointestinal disorders: Epidemiology, mechanisms and management. Journal of Neurogastroenterology and Motility 18(1): 13–18. DOI: 10.5056/jnm.2012.18.1.13.

36.

Zigmond

Snaith

(1983) The hospital anxiety and depression scale. Acta Psychiatrica Scandinavica 67(6): 361–370.