Irritable Bowel Syndrome Is Positively Related to Metabolic Syndrome: A Population-Based Cross-Sectional Study

Irritable bowel syndrome is a common gastrointestinal disorder that may affect dietary pattern, food digestion, and nutrient absorption. The nutrition-related factors are closely related to metabolic syndrome, implying that irritable bowel syndrome may be a potential risk factor for metabolic syndrome. However, few epidemiological studies are available which are related to this potential link. The purpose of this study is to determine whether irritable bowel syndrome is related to metabolic syndrome among middle-aged people. We designed a cross-sectional study of 1,096 subjects to evaluate the relationship between irritable bowel syndrome and metabolic syndrome and its components. Diagnosis of irritable bowel syndrome was based on the Japanese version of the Rome III Questionnaire. Metabolic syndrome was defined according to the criteria of the American Heart Association scientific statements of 2009. Dietary consumption was assessed via a validated food frequency questionnaire. Principal-components analysis was used to derive 3 major dietary patterns: “Japanese”, “sweets-fruits”, and “Izakaya (Japanese Pub) “from 39 food groups. The prevalence of irritable bowel syndrome and metabolic syndrome were 19.4% and 14.6%, respectively. No significant relationship was found between the dietary pattern factor score tertiles and irritable bowel syndrome. After adjustment for potential confounders (including dietary pattern), the odds ratio (95% confidence interval) of having metabolic syndrome and elevated triglycerides for subjects with irritable bowel syndrome as compared with non-irritable bowel syndrome are 2.01(1.13–3.55) and 1.50(1.03–2.18), respectively. Irritable bowel syndrome is significantly related to metabolic syndrome and it components. This study is the first to show that irritable bowel syndrome was significantly related to a higher prevalence of metabolic syndrome and elevated triglycerides among an adult population. The findings suggest that the treatment of irritable bowel syndrome may be a potentially beneficial factor for the prevention of metabolic syndrome. Further study is needed to clarify this association.     

Irritable bowel syndrome in the general population.

OBJECTIVE--To determine the prevalence of symptoms compatible with a clinical diagnosis of irritable bowel syndrome in the general population. DESIGN--Validated postal questionnaire sent to 2280 subjects randomly selected in 10 year age bands from the lists of eight general practitioners. The Manning criteria were used to define irritable bowel syndrome. SETTING--Urban population in Southampton and mixed urban-rural population in Andover, Hampshire. RESULTS--A response of 71% yielded 1620 questionnaires for analysis, of which 412 (25%) reported more than six episodes of abdominal pain in the preceding year, with 350 (22%) reporting symptoms consistent with the diagnosis of irritable bowel syndrome. The male: female ratio was 1:1.38. More subjects with irritable bowel syndrome had constipation and diarrhoea and 35% with the syndrome reported rectal bleeding compared with an overall prevalence of 20%. Other symptoms and conditions including heartburn, dyspepsia, flushing, palpitations, migraine, and urinary symptoms were significantly more common in the group with irritable bowel syndrome. Abdominal pain in childhood was more common in the subjects with irritable bowel syndrome (12%) than without (3%). One third of the group with irritable bowel syndrome had sought medical advice during the study period (male:female ratio 1:1.21); consultation behaviour was influenced by age and the presence of associated symptoms, varied considerably among patients registered with different general practitioners, and was poorly correlated with symptom severity. CONCLUSION--Symptoms consistent with a diagnosis of irritable bowel syndrome are present in almost one quarter of the general population and tend to be associated with a number of other complaints and conditions, some of which may reflect smooth muscle dysfunction.     

Abnormalities of sleep in patients with the chronic fatigue syndrome.

OBJECTIVE--To determine whether patients with the chronic fatigue syndrome have abnormalities of sleep which may contribute to daytime fatigue. DESIGN--A case-control study of the sleep of patients with the chronic fatigue syndrome and that of healthy volunteers. SETTING--An infectious disease outpatient clinic and subjects'' homes. SUBJECTS--12 patients who met research criteria for the chronic fatigue syndrome but not for major depressive disorder and 12 healthy controls matched for age, sex, and weight. MAIN OUTCOME MEASURES--Subjective reports of sleep from patients'' diaries and measurement of sleep patterns by polysomnography. Subjects'' anxiety, depression, and functional impairment were assessed by interview. RESULTS--Patients with the chronic fatigue syndrome spent more time in bed than controls (544 min v 465 min, p < 0.001) but slept less efficiently (90% v 96%, p < 0.05) and spent more time awake after initially going to sleep (31.9 min v 16.6 min, p < 0.05). Seven patients with the chronic fatigue syndrome had a sleep disorder (four had difficulty maintaining sleep, one had difficulty getting to sleep, one had difficulty in both initiating and maintaining sleep, and one had hypersomnia) compared with none of the controls (p = 0.003). Those with sleep disorders showed greater functional impairment than the remaining five patients (score on general health survey 50.4% v 70.4%, p < 0.05), but their psychiatric scores were not significantly different. CONCLUSIONS--Most patients with the chronic fatigue syndrome had sleep disorders, which are likely to contribute to daytime fatigue. Sleep disorders may be important in the aetiology of the syndrome.     

Irritable bowel syndrome and abdominoplasty

Irritable bowel syndrome is a chronic disease involving pain or discomfort relieved by defecation and associated with a change in frequency or consistency of the stools. The effect of abdominoplasty on patients with irritable bowel syndrome has not been elucidated, so advising patients with irritable bowel syndrome about the effects of surgery on their disease was difficult. One hundred female patients from a pool of 120 patients responded to a questionnaire relating to abdominoplasty surgery. Follow-up ranged from 6 months to 2 years. Patients completed questionnaires formulated on the basis of Rome II Diagnostic Criteria. Of the 100 patients, nine had true irritable bowel syndrome, nine had moderate symptoms and were receiving medication (not true irritable bowel syndrome), 16 had mild symptoms on occasional medication, and 66 had no symptoms of irritable bowel syndrome before surgery. Of the true irritable bowel syndrome patients, all had symptomatic improvement with decreased medication, eight of the nine patients with moderate symptoms improved markedly, and five of the 16 patients with mild symptoms improved significantly. No patient had any initiation or deterioration of symptoms. It is thus concluded that the symptoms of irritable bowel syndrome are certainly not worsened, in the short term, by surgery, and may be alleviated or improved in most significant cases.     

Biofeedback treatment for headaches,Raynaud's disease,essential hypertension,and irritable bowel syndrome: A review of the long-term follow-up literature

Long-term follow-up evidence for biofeedback treatment of headaches, Raynaud's disease, essential hypertension, and the irritable bowel syndrome was reviewed. Acknowledging the difficulties with cross-study comparisons, the following general success rate were determined: primary idiopathic Raynaud's disease—70%, or better; vascular headache—70%, or better; mixed headache—about 60%; and muscle contraction headache—50%, or less. With relatively fewer patients, successful outcomes with the irritable bowel syndrome and secondary Raynaud's phenomenon were roughly 60% and 40%, respectively. Few cases of clinically significant long-term decreases in diastolic blood pressure were demonstrated; however, the need for medication was reduced or eliminated in some patients. There were indications that biofeedback combined with psychotherapy resulted in highest success rates. No differences were found in effectiveness between biofeedback, other relaxation techniques, and biofeedback in combination with relaxation techniques—all had essentially comparable rates of success. No correlations between physiological and psychological measures of condition at follow-up were reported. Implications and interpretations of these findings are discussed.     

Postviral fatigue syndrome: time for a new approach

Controversial views on the postviral fatigue syndrome (“myalgic encephalomyelitis”) were critically appraised in their historical context and recent advances in research (virology, immunology, neurophysiology, histopathology, and epidemiology) reviewed. Flaws detected in certain aspects of recent research included in particular failure to define fatigue, inadequate assessment of psychological features, and absent or inappropriate control groups. The findings suggest that the fruitless dichotomy of “organic versus functional” should be replaced by a multifactorial approach. Most important, epidemiological studies with explicit operational case definition are essential before progress can be made in the management of this distressing disorder.     

Pre-referral rectal artesunate in severe malaria: flawed trial

Introduction

Irritable bowel syndrome affects as many as 14% of high school-aged students. Symptoms include discomfort in the abdomen, along with diarrhea and/or constipation and other gastroenterological symptoms that can significantly impact quality of life and daily functioning. Emotional stress appears to exacerbate irritable bowel syndrome symptoms suggesting that mind-body interventions reducing arousal may prove beneficial. For many sufferers, symptoms can be traced to childhood and adolescence, making the early manifestation of irritable bowel syndrome important to understand. The current study will focus on young people aged 14-26 years with irritable bowel syndrome. The study will test the potential benefits of Iyengar yoga on clinical symptoms, psychospiritual functioning and visceral sensitivity. Yoga is thought to bring physical, psychological and spiritual benefits to practitioners and has been associated with reduced stress and pain. Through its focus on restoration and use of props, Iyengar yoga is especially designed to decrease arousal and promote psychospiritual resources in physically compromised individuals. An extensive and standardized teacher-training program support Iyengar yoga's reliability and safety. It is hypothesized that yoga will be feasible with less than 20% attrition; and the yoga group will demonstrate significantly improved outcomes compared to controls, with physiological and psychospiritual mechanisms contributing to improvements.

Methods/Design

Sixty irritable bowel syndrome patients aged 14-26 will be randomly assigned to a standardized 6-week twice weekly Iyengar yoga group-based program or a wait-list usual care control group. The groups will be compared on the primary clinical outcomes of irritable bowel syndrome symptoms, quality of life and global improvement at post-treatment and 2-month follow-up. Secondary outcomes will include visceral pain sensitivity assessed with a standardized laboratory task (water load task), functional disability and psychospiritual variables including catastrophizing, self-efficacy, mood, acceptance and mindfulness. Mechanisms of action involved in the proposed beneficial effects of yoga upon clinical outcomes will be explored, and include the mediating effects of visceral sensitivity, increased psychospiritual resources, regulated autonomic nervous system responses and regulated hormonal stress response assessed via salivary cortisol.

Trial registration

ClinicalTrials.gov NCT01107977.     

A Systematic Review of Probiotic Interventions for Gastrointestinal Symptoms and Irritable Bowel Syndrome in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME)

Gastrointestinal (GI) symptoms and irritable bowel (IB) symptoms have been associated with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). The aim of this study was to conduct a systematic review of these symptoms in CFS/ME, along with any evidence for probiotics as treatment. Pubmed, Scopus, Medline (EBSCOHost) and EMBASE databases were searched to source relevant studies for CFS/ME. The review included any studies examining GI symptoms, irritable bowel syndrome (IBS) and/or probiotic use. Studies were required to report criteria for CFS/ME and study design, intervention and outcome measures. Quality assessment was also completed to summarise the level of evidence available. A total of 3381 publications were returned using our search terms. Twenty-five studies were included in the review. Randomised control trials were the predominant study type (n?=?24). Most of the studies identified examined the effect of probiotic supplementation on the improvement of IB symptoms in IBS patients, or IB symptoms in CFS/ME patients, as well as some other significant secondary outcomes (e.g. quality of life, other gastrointestinal symptoms, psychological symptoms). The level of evidence identified for the use of probiotics in IBS was excellent in quality; however, the evidence available for the use of probiotic interventions in CFS/ME was poor and limited. There is currently insufficient evidence for the use of probiotics in CFS/ME patients, despite probiotic interventions being useful in IBS. The studies pertaining to probiotic interventions in CFS/ME patients were limited and of poor quality overall. Standardisation of protocols and methodology in these studies is required.     

Patients' accounts of being removed from their general practitioner's list: qualitative study

Objective To explore patients'' accounts of being removed from a general practitioner''s list.Design Qualitative analysis of semistructured interviews.Setting Patients'' homes in Leicestershire.Participants 28 patients who had recently been removed from a general practitioner''s list.Results The removed patients gave an account of themselves as having genuine illnesses needing medical care. In putting their case that their removal was unjustified, patients were concerned to show that they were “good” patients who complied with the rules that they understood to govern the doctor-patient relationship: they tried to cope with their illness and follow medical advice, used general practice services “appropriately,” were uncomplaining, and were polite with doctors. Removed patients also used their accounts to characterise the removing general practitioner as one who broke the lay rules of the doctor-patient relationship. These “bad” general practitioners were rude, impersonal, uncaring, and clinically incompetent and lied to patients. Patients felt very threatened by being removed from their general practitioner''s list; they experienced removal as an attack on their right to be an NHS patient, as deeply distressing, and as stigmatising.Conclusions Removal is an overwhelmingly negative and distressing experience for patients. Many of the problems encountered by removed patients may be remediable through general practices having an explicit policy on removal and procedures in place to help with “difficult” patients.     

Development and Evaluation of a Parenting Resilience Elements Questionnaire (PREQ) Measuring Resiliency in Rearing Children with Developmental Disorders

We developed a parenting resilience elements questionnaire (PREQ) measuring the degree to which mothers possess elements that aid in adapting to challenges and difficulties related to children with developmental disorders (DD). A total of 424 parents of children with DD were recruited from five medical institutes. Psychometric properties of PREQ were evaluated using data of 363 mothers of children with DD. Furthermore, multiple regression analysis was performed, predicting depressive symptoms and parenting behavior with PREQ subscales, a general health questionnaire, and the total difficulties score of a strength and difficulties questionnaire. Factor analysis revealed three reliable factors: “knowledge of the child’s characteristics,” “perceived social supports,” and “positive perceptions of parenting.” Moreover, multiple regression analysis showed that “knowledge of the child’s characteristics” was associated with parenting behavior, whereas “perceived social supports” predicted depressive symptoms; “positive perceptions of parenting” influenced both parenting behavior and depressive symptoms. These findings indicated that the PREQ may be used as a scale measuring resiliency in mothers of children with DD and is useful for evaluating their parenting ability in clinical interventions.     

“Complications” of the Landry-Guillain-Barré-Strohl syndrome

Prognosis for life in the Landry-Guillain-Barré-Strohl syndrome is dependent upon the development of respiratory and non-respiratory “complications” and their successful management. Review of the literature, a case history, and a study of 14 patients with this syndrome at the University Hospital, Edmonton, indicate that “complications” can be anticipated in virtually all areas of acute care management, including respiratory, gastrointestinal, urinary tract, central and autonomic nervous systems, metabolic, cardiovascular, and infectious disease. The proper management of patients with the Landry-Guillain-Barré-Strohl syndrome demands an awareness of the totality of care required and the presence of a hospital system that provides for vital system monitoring and support, and for ready interdisciplinary consultation.     

Qualitative study of views of health professionals and patients on guided self management plans for asthma

ObjectivesTo explore the views held by general practitioners, practice nurses, and patients about the role of guided self management plans in asthma care.DesignQualitative study using nine focus groups that each met on two occasions.SettingSouth Wales.Subjects13 asthma nurses, 11 general practitioners (six with an interest in asthma), and 32 patients (13 adults compliant with treatment, 12 non-compliant adults, and seven teenagers).ResultsNeither health professionals nor patients were enthusiastic about guided self management plans, and, although for different reasons, almost all participants were ambivalent about their usefulness or relevance. Most professionals opposed their use. Few patients reported sustained use, and most felt that plans were largely irrelevant to them. The attitudes associated with these views reflect the gulf between the professionals'' concept of the “responsible asthma patient” and the patients'' view.ConclusionsAttempts to introduce self guided management plans in primary care are unlikely to be successful. A more patient centred, patient negotiated plan is needed for asthma care in the community.     

Helicobacter pylori test and treat versus proton pump inhibitor in initial management of dyspepsia in primary care: multicentre randomised controlled trial (MRC-CUBE trial)

Objective To determine the cost effectiveness of Helicobacter pylori “test and treat” compared with empirical acid suppression in the initial management of patients with dyspepsia in primary care.Design Randomised controlled trial.Setting 80 general practices in the United Kingdom.Participants 699 patients aged 18-65 who presented to their general practitioner with epigastric pain, heartburn, or both without “alarm symptoms” for malignancy.Intervention H pylori ¹³C urea breath test plus one week of eradication treatment if positive or proton pump inhibitor alone; subsequent management at general practitioner’s discretion.Main outcome measures Cost effectiveness in cost per quality adjusted life year (QALY) (EQ-5D) and effect on dyspeptic symptoms at one year measured with short form Leeds dyspepsia questionnaire.Results 343 patients were randomised to testing for H pylori, and 100 were positive. The successful eradication rate was 78%. 356 patients received proton pump inhibitor for 28 days. At 12 months no significant differences existed between the two groups in QALYs, costs, or dyspeptic symptoms. Minor reductions in costly resource use over the year in the test and treat group “paid back” the initial cost of the intervention.Conclusions Test and treat and acid suppression are equally cost effective in the initial management of dyspepsia. Empirical acid suppression is an appropriate initial strategy. As costs are similar overall, general practitioners should discuss with patients at which point to consider H pylori testing.Trial registration Current Controlled Trials ISRCTN87644265.     

Psychoneurotic symptomatology in the irritable bowel syndrome: a study of reporters and non-reporters.

An appreciable proportion of the general population have the irritable bowel syndrome but do not report it. Results of psychological assessments showed that outpatients with the syndrome and non-reporters of it were psychologically similar, but both groups showed more somatic distress than normal controls. Anxiety, depression, obsessive compulsion, and interpersonal sensitivity were similar in both groups with the syndrome and the normal controls. The preponderance of women referred to outpatient clinics may reflect sociological factors rather than the severity of the irritable bowel syndrome.     

“Sicca Complex” in Liver Disease

Sixty-three patients with liver disease were studied for the presence of the components of Sjögren''s syndrome. The “sicca complex” (that is, patients without arthritis) was detected in 42% of patients with active chronic hepatitis, 72% with primary biliary cirrhosis, and 38% with cryptogenic cirrhosis. One patient with active chronic hepatitis and one with primary biliary cirrhosis had rheumatoid arthritis. No evidence of Sjögren''s syndrome was detected in seven patients with alcoholic cirrhosis. It is suggested that the sicca complex and autoimmune liver disease may be part of a systemic disorder in which immunological mechanisms are concerned in the pathogenesis.     

NEW VISTAS IN PSYCHOSOMATIC MEDICINE

Further understanding in the field of psychosomatic medicine has come to light recently as the result of new approaches and methods of research.Such diseases as hypertension, ulcerative colitis, rheumatoid arthritis, peptic ulcer, diabetes and cardiovascular dysfunction may represent the body''s method of adapting to chronic stress, according to Selye''s concept of the general adaptation syndrome, with the phases of alarm, resistance and exhaustion.It has been postulated that unconscious dynamics of which patients are unaware are crucial in the understanding and interpretation of physiological research and therapy of patients with psychosomatic disorders.The concept of partial regression was applicable to patients with psychosomatic illness who were highly successful in social, economic and professional spheres. The illness was viewed as a protection against psychological regression by limited somatic regression.Pilot studies suggested that patients seriously ill with such disorders as ulcerative colitis and asthma responded favorably to enforced psychological regression and exploitation of dependency by excessive coddling, babying and mothering by an “all-giving” physician in a hospital setting.Good physician-patient relationship remains the keystone in therapy and is the common denominator to many so-called successful modes of treatment.     

Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome

Objective To investigate whether placebo effects can experimentally be separated into the response to three components—assessment and observation, a therapeutic ritual (placebo treatment), and a supportive patient-practitioner relationship—and then progressively combined to produce incremental clinical improvement in patients with irritable bowel syndrome. To assess the relative magnitude of these components.Design A six week single blind three arm randomised controlled trial.Setting Academic medical centre.Participants 262 adults (76% women), mean (SD) age 39 (14), diagnosed by Rome II criteria for and with a score of ≥150 on the symptom severity scale.Interventions For three weeks either waiting list (observation), placebo acupuncture alone (“limited”), or placebo acupuncture with a patient-practitioner relationship augmented by warmth, attention, and confidence (“augmented”). At three weeks, half of the patients were randomly assigned to continue in their originally assigned group for an additional three weeks.Main outcome measures Global improvement scale (range 1-7), adequate relief of symptoms, symptom severity score, and quality of life.Results At three weeks, scores on the global improvement scale were 3.8 (SD 1.0) v 4.3 (SD 1.4) v 5.0 (SD 1.3) for waiting list versus “limited” versus “augmented,” respectively (P<0.001 for trend). The proportion of patients reporting adequate relief showed a similar pattern: 28% on waiting list, 44% in limited group, and 62% in augmented group (P<0.001 for trend). The same trend in response existed in symptom severity score (30 (63) v 42 (67) v 82 (89), P<0.001) and quality of life (3.6 (8.1) v 4.1 (9.4) v 9.3 (14.0), P<0.001). All pairwise comparisons between augmented and limited patient-practitioner relationship were significant: global improvement scale (P<0.001), adequate relief of symptoms (P<0.001), symptom severity score (P=0.007), quality of life (P=0.01).Results were similar at six week follow-up.Conclusion Factors contributing to the placebo effect can be progressively combined in a manner resembling a graded dose escalation of component parts. Non-specific effects can produce statistically and clinically significant outcomes and the patient-practitioner relationship is the most robust component.Trial registration Clinical Trials NCT00065403.     

Screening Primary-Care Patients Forgoing Health Care for Economic Reasons

Background

Growing social inequities have made it important for general practitioners to verify if patients can afford treatment and procedures. Incorporating social conditions into clinical decision-making allows general practitioners to address mismatches between patients'' health-care needs and financial resources.

Objectives

Identify a screening question to, indirectly, rule out patients'' social risk of forgoing health care for economic reasons, and estimate prevalence of forgoing health care and the influence of physicians'' attitudes toward deprivation.

Design

Multicenter cross-sectional survey.

Participants

Forty-seven general practitioners working in the French–speaking part of Switzerland enrolled a random sample of patients attending their private practices.

Main Measures

Patients who had forgone health care were defined as those reporting a household member (including themselves) having forgone treatment for economic reasons during the previous 12 months, through a self-administered questionnaire. Patients were also asked about education and income levels, self-perceived social position, and deprivation levels.

Key Results

Overall, 2,026 patients were included in the analysis; 10.7% (CI95% 9.4–12.1) reported a member of their household to have forgone health care during the 12 previous months. The question “Did you have difficulties paying your household bills during the last 12 months” performed better in identifying patients at risk of forgoing health care than a combination of four objective measures of socio-economic status (gender, age, education level, and income) (R² = 0.184 vs. 0.083). This question effectively ruled out that patients had forgone health care, with a negative predictive value of 96%. Furthermore, for physicians who felt powerless in the face of deprivation, we observed an increase in the odds of patients forgoing health care of 1.5 times.

Conclusion

General practitioners should systematically evaluate the socio-economic status of their patients. Asking patients whether they experience any difficulties in paying their bills is an effective means of identifying patients who might forgo health care.     

Towards positive diagnosis of the irritable bowel.

A questionnaire to establish the presence of 15 symptoms thought to be typical of the irritable bowel syndrome (IBS) was given to 109 unselected patients referred to gastroenterology or surgery clinics with abdominal pain or a change in bowel habit or both. Review of case records 17--26 months later established a definite diagnosis of IBS in 32 patients and of organic disease in 33. Four symptoms were significantly more common among patients with IBS--namely, distension, relief of pain with bowel movement, and looser and more frequent bowel movements with the onset of pain. Mucus and a sensation of incomplete evacuation were also common in these patients. The more of these symptoms that were present the more likely was it that the patient''s pain or altered bowel habit, or both, was due to IBS. We conclude that a careful history can increase diagnostic confidence and reduce the amount of investigation in many patients with chronic abdominal pain.     

Catechol-O-Methyltransferase val158met Polymorphism Predicts Placebo Effect in Irritable Bowel Syndrome

Identifying patients who are potential placebo responders has major implications for clinical practice and trial design. Catechol-O-methyltransferase (COMT), an important enzyme in dopamine catabolism plays a key role in processes associated with the placebo effect such as reward, pain, memory and learning. We hypothesized that the COMT functional val158met polymorphism, was a predictor of placebo effects and tested our hypothesis in a subset of 104 patients from a previously reported randomized controlled trial in irritable bowel syndrome (IBS). The three treatment arms from this study were: no-treatment (“waitlist”), placebo treatment alone (“limited”) and, placebo treatment “augmented” with a supportive patient-health care provider interaction. The primary outcome measure was change from baseline in IBS-Symptom Severity Scale (IBS-SSS) after three weeks of treatment. In a regression model, the number of methionine alleles in COMT val158met was linearly related to placebo response as measured by changes in IBS-SSS (p = .035). The strongest placebo response occurred in met/met homozygotes treated in the augmented placebo arm. A smaller met/met associated effect was observed with limited placebo treatment and there was no effect in the waitlist control. These data support our hypothesis that the COMT val158met polymorphism is a potential biomarker of placebo response.