Derivation and validation of a diagnostic test for irritable bowel syndrome using latent class analysis

A New Approach for Classifying Fetal Growth Restriction

BACKGROUND

Fetal growth restriction is commonly defined using small for gestational age (SGA) birth (birthweight < 10th percentile) as a proxy, but this approach is problematic because most SGA infants are small but healthy. In this proof-of-concept study, we sought to develop a new approach for identifying fetal growth restriction at birth that combines information on multiple, imperfect measures of fetal growth restriction in a probabilistic manner.

METHODS

We combined information on birthweight, placental weight, placental malperfusion lesions, maternal disease, and fetal acidemia using latent profile analysis to classify fetal growth in births at the Royal Victoria Hospital in Montreal, Canada, 2001-2009. We examined the clinical characteristics and health outcomes of infants classified as growth-restricted and nongrowth-restricted by our model, and among the subgroup of growth-restricted infants who had a birthweight ≥10th percentile (i.e., would have been missed by the conventional SGA proxy).

RESULTS

Among 26,077 births, 345 (1.3%) were classified as growth-restricted by our latent profile model. Growth-restricted infants were more likely than nongrowth-restricted infants to have an Apgar score <7 (10% vs. 2%), have hypoglycemia at birth (17% vs. 3%), require neonatal intensive care unit admission (59% vs. 6%), die in the perinatal period (3.8% vs. 0.2%), and require an emergency cesarean delivery (42% vs. 15%). Risks remained elevated in growth-restricted infants who were not SGA, suggesting our model identified at-risk infants not detected using the SGA proxy.

CONCLUSIONS

Latent profile analysis is a promising strategy for classifying growth restriction at birth in fetal growth restriction research.

Comparison of the Rome IV criteria with the Rome III criteria for the diagnosis of irritable bowel syndrome in secondary care

OBJECTIVES

Despite being proposed 4 years ago, there has been no independent validation study of the Rome IV criteria for IBS. We assessed their performance for the diagnosis of IBS in secondary care and compared them with the previous iteration, the Rome III criteria.

DESIGN

We collected complete symptom data from consecutive adult patients with suspected IBS referred to a single UK clinic. All subjects underwent relatively standardised workup, with assessors blinded to symptom status. The reference standard used to confirm IBS was the presence of lower abdominal pain or discomfort in association with altered stool form or frequency, in a patient with no evidence of organic gastrointestinal disease after investigation. Sensitivity, specificity and positive and negative likelihood ratios (LRs), with 95% CIs, were calculated for each of the diagnostic criteria.

RESULTS

The level of agreement between the Rome IV and Rome III criteria was good (kappa=0.65). Compared with the reference standard, sensitivity and specificity of the Rome IV criteria in 572 patients (431 (75.3%) women, mean age 36.5 years) were 82.4% and 82.9%, respectively. Positive and negative LRs for the Rome IV criteria were 4.82 (95% CI 3.30 to 7.28) and 0.21 (95% CI 0.17 to 0.26), respectively. The Rome IV criteria performed best in those with IBS with constipation or mixed bowel habits. In 471 patients (350 (74.3%) women, mean age 36.7 years), compared with the reference standard, the sensitivity and specificity of the Rome III criteria were 85.8% and 65.0%; positive and negative LRs were 2.45 (95% CI 1.90 to 3.27) and 0.22 (0.16 to 0.29), respectively. Incorporating mood and extraintestinal symptom reporting into diagnostic criteria did not improve their performance significantly.

CONCLUSIONS

The Rome IV criteria performed significantly better than the Rome III criteria in diagnosing IBS in this single centre secondary care study, although the clinical relevance of this is uncertain.

Overlapping of irritable bowel syndrome with erosive esophagitis and the performance of Rome criteria in diagnosing IBS in a clinical setting

Irritable bowel syndrome (IBS) and gastroesophageal reflux disease (GERD) overlap. It is not clear whether GERD is caused by non-erosive esophagitis, or erosive esophagitis. The Rome criteria are not widely used for the diagnosis of IBS in the clinic. In total, 1,489 IBS patients without red flags were included in the present retrospective study. They comprised of 1,331 females and 158 males with a mean age of 51 years. The diagnosis of IBS was verified by endoscopic and histopathological examinations. Whereas erosive esophagitis occurred in 97% of patients, only 66% had GERD symptoms. Endoscopy and histopathological examinations revealed that 1.4% of the IBS patients with diarrhea as the predominant symptom had other organic gastrointestinal diseases: 0.3% with celiac disease, 0.2% with Crohn's disease, 0.07% with ulcerative colitis, 0.6% with microscopic colitis, and 0.2% with colon cancer. Applying the Rome III criteria produced a sensitivity of 100% [95% confidence intervals (CI)=99.8–100.0%] a specificity of 98.7% (95% CI=98.0–99.2%), a positive likelihood ratio of 76.9%, and a negative likelihood ratio of 0%. IBS is associated with erosive esophagitis. Applying Rome III criteria without red flags and history, was effective in diagnosing IBS. Celiac disease and microscopic colitis should be considered as alternative diagnoses.

Combining Rome III criteria with alarm symptoms provides high specificity but low sensitivity for functional gastrointestinal disorders in children

AIM

This study aimed to validate the Rome III criteria and alarm symptoms with regard to their ability to discriminate between organic and functional diagnoses in children with gastrointestinal complaints.

METHODS

We recruited 258 children aged four years to 17 years who consulted a paediatrician in secondary or tertiary care in Stockholm from January 2013 to May 2014 due to gastrointestinal complaints. A symptom questionnaire based on the official Questionnaire on Pediatric Gastrointestinal Symptoms Rome III, including questions on alarm symptoms, was used. A diagnostic review of their medical records was also carried out.

RESULTS

The reference diagnoses were organic (16%), pain-predominant functional gastrointestinal disorders (54%) and other functional diseases (30%). When the reported symptoms that fulfilled the Rome III criteria for pain-predominant functional gastrointestinal disorders were combined with an absence of alarm symptoms, they had a high specificity (0.90) for a functional diagnosis, but a low sensitivity (0.15). Alarm symptoms were equally common in patients with organic (83%) and functional diseases (80%, p = 0.66).

CONCLUSIONS

Combining the Rome III criteria and an absence of alarm symptoms from patient questionnaires had high specificity but low sensitivity when diagnosing pain-predominant functional gastrointestinal disorders in children seeking medical care for gastrointestinal complaints.

Cyclic vomiting syndrome is a prevalent and under-recognized condition in the gastroenterology outpatient clinic

BACKGROUND

Cyclic vomiting syndrome (CVS) is a functional gastrointestinal disorder (FGID) characterized by intermittent episodes of nausea and vomiting. Our aim was to report its prevalence and associated features.

METHODS

Data concerning demographics, symptoms, and psychiatric comorbidity were collected. Symptoms compatible with CVS were classified as per Rome III criteria. We recorded whether a diagnosis of CVS was considered in patients after negative investigation. We compared demographics and association with other FGIDs in patients with and without CVS.

KEY RESULTS

920 of 1002 patients provided data. Of the 920 patients, 112 (12.2%) had symptoms compatible with CVS. Thirteen (11.6%) of these had an organic cause for their symptoms, but 99 patients (88.4%) were deemed to have CVS (prevalence=10.8%). Organic causes for symptoms compatible with CVS included gastroparesis, large hiatus hernia, achalasia, and small bowel obstruction. Only 39.4% of patients with CVS were asked about vomiting symptoms at their initial consultation, and a diagnosis of CVS was considered in only four (4.0%) of the 99 patients. CVS was associated with younger age, tobacco smoking, never having married, psychiatric comorbidity, and presence of symptoms compatible with other FGIDs (P≤.01).

CONCLUSIONS AND INFERENCES

Prevalence of CVS in this outpatient gastroenterology adult population was 10.8%. Identified associations included younger age, tobacco smoking, psychiatric comorbidity, and symptoms compatible with other FGIDs. The condition was considered as a possible diagnosis in <5% of patients who met the diagnostic criteria.

Mixture model analysis identifies irritable bowel syndrome subgroups characterised by specific profiles of gastrointestinal, extraintestinal somatic and psychological symptoms

BACKGROUND

Current subgrouping of Irritable Bowel Syndrome (IBS) is exclusively based on stool consistency without considering other relevant gastrointestinal (GI), extraintestinal somatic or psychological features.

AIM

To identify subgroups based on a comprehensive set of IBS-related parameters.

METHODS

Mixture model analysis was used, with the following input variables: 13 single-item scores from the IBS-specific Gastrointestinal Symptom Rating Scale, average stool consistency and frequency from a 7-day Bristol Stool Form diary, 12 single-item extraintestinal symptom scores from the Patient Health Questionnaire-12, and anxiety and depression subscale scores from the Hospital Anxiety and Depression scale. The resulting latent subgroups were compared regarding symptom profiles using analysis of variance followed by pair-wise comparisons.

RESULTS

One hundred and seventy-two IBS patients (Rome III; 69% female; mean age 33.7 [range 18-60] years) were included. The optimal subgrouping showed six latent groups, characterised by: (I) constipation with low comorbidities, (II) constipation with high comorbidities, (III) diarrhoea with low comorbidities, (IV) diarrhoea and pain with high comorbidities, (V) mixed GI symptoms with high comorbidities, (VI) a mix of symptoms with overall mild severity. The subgroups showed differences in the distribution of Rome III-subtypes, IBS severity, presence of anxiety and depression, and gender, but not regarding age, IBS duration or reported post-infectious onset of IBS.

CONCLUSIONS

This model-based subgrouping of IBS partly supports the distinction of subgroups based on bowel habits, but additionally distinguishes subgroups with or without co-morbid extraintestinal somatic and psychological symptoms. The resulting groups show specific profiles of symptom combinations.

Sensitivity, Specificity, Predictive Values, and Accuracy of Three Diagnostic Tests to Predict Inferior Alveolar Nerve Blockade Failure in Symptomatic Irreversible Pulpitis

INTRODUCTION

The inferior alveolar nerve block (IANB) is the most common anesthetic technique used on mandibular teeth during root canal treatment. Its success in the presence of preoperative inflammation is still controversial. The aim of this study was to evaluate the sensitivity, specificity, predictive values, and accuracy of three diagnostic tests used to predict IANB failure in symptomatic irreversible pulpitis (SIP).

METHODOLOGY

A cross-sectional study was carried out on the mandibular molars of 53 patients with SIP. All patients received a single cartridge of mepivacaine 2% with 1 : 100000 epinephrine using the IANB technique. Three diagnostic clinical tests were performed to detect anesthetic failure. Anesthetic failure was defined as a positive painful response to any of the three tests. Sensitivity, specificity, predictive values, accuracy, and ROC curves were calculated and compared and significant differences were analyzed.

RESULTS

IANB failure was determined in 71.7% of the patients. The sensitivity scores for the three tests (lip numbness, the cold stimuli test, and responsiveness during endodontic access) were 0.03, 0.35, and 0.55, respectively, and the specificity score was determined as 1 for all of the tests. Clinically, none of the evaluated tests demonstrated a high enough accuracy (0.30, 0.53, and 0.68 for lip numbness, the cold stimuli test, and responsiveness during endodontic access, resp.). A comparison of the areas under the curve in the ROC analyses showed statistically significant differences between the three tests (p < 0.05).

CONCLUSION

None of the analyzed tests demonstrated a high enough accuracy to be considered a reliable diagnostic tool for the prediction of anesthetic failure.

Editorial: latent class analysis to improve confidence in the diagnosis of IBS

Linked Content

This article is linked to Sood et al papers. To view these articles visit https://doi.org/10.1111/apt.14012 and https://doi.org/10.1111/apt.13949.