[Evaluation of enzyme-linked immunosorbent assay for the diagnosis of Helicobacter pylori infection in children and adolescents]

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Seroprevalence of Helicobacter pylori infection among children of low socioeconomic level in São Paulo

CONTEXT AND OBJECTIVE

Helicobacter pylori infection is mainly acquired during childhood, and is associated with significant morbidity in adults. The aim here was to evaluate the seroprevalence and risk factors of H. pylori infection among children of low socioeconomic level attended at a public hospital in São Paulo, Brazil.

DESIGN AND SETTING

Cross-sectional study, among patients attended at an outpatient clinic.

METHODS

326 children were evaluated (150 boys and 176 girls; mean age 6.82 ± 4.07 years) in a cross-sectional study. Patients with chronic diseases or previous H. pylori treatment, and those whose participation was not permitted by the adult responsible for the child, were excluded. The adults answered a demographic questionnaire and blood samples were collected. The serological test used was Cobas Core II, a second-generation test. Titers > 5 U/ml were considered positive.

RESULTS

H. pylori infection was diagnosed in 116 children (35.6%). Infected children were older than uninfected children (7.77 ± 4.08 years versus 5.59 ± 3.86 years; p < 0.0001). The seroprevalence increased from 20.8% among children aged two to four years, to 58.3% among those older than 12 years. There were no significant relationships between seropositivity and gender, color, breastfeeding, number of people in the home, number of rooms, bed sharing, living in a shantytown, maternal educational level, family income or nutritional status. In multivariate analysis, the only variable significantly associated with H. pylori seropositivity was age.

CONCLUSION

Infection had intermediate prevalence in the study population, and age was associated with higher prevalence.

Spontaneous elimination of Helicobacter pylori infection in a cohort of asymptomatic school children by enzyme-linked immunosorbent assay polyclonal antigen in stool

GOAL

To determine the natural evolution of the Helicobacter pylori infection through the fecal antigen of the H. pylori test in a cohort of school children during 2 consecutive years.

BACKGROUND

Studies have suggested that the spontaneous elimination rate is higher in developing countries, possibly owing to higher incidence rate.

STUDY

One hundred twelve children attending a day care center for the sons and daughters of university employees were evaluated yearly in a 2-year period using the H. pylori stool antigen test. Parents answered a questionnaire with demographic data at baseline. The test was performed according to previously standardized procedures, and results lesser than 0.140 were regarded as negative; higher than 0.016 were regarded as positive.

RESULTS

Age ranged from 0.7 to 7.48 years (3.67+/-1.98 y) at baseline, with 58% female and 42% male. H. pylori prevalence was 12.5% (14/112). There was a trend to associate low income (P=0.06), ethnicity non-white (P=0.075), and smaller house (P=0.079) to H. pylori infection at baseline in univariate analysis. Nevertheless, age was the only variable associated to prevalence at multivariate analysis. There was no significant association between H. pylori infection and intestinal parasites. There was only one new infection during the study period (incidence rate 0.53%), and 4 children cleared the infection (elimination rate 2.15%). All those children were older than 4 years.

CONCLUSIONS

Spontaneous eradication of the infection was more frequent than incidence of infection in this cohort.

13C-urea breath test to diagnose Helicobacter pylori infection in children aged up to 6 years

BACKGROUND

13C-urea breath test (13C-UBT) is an accurate noninvasive tool for diagnosis of Helicobacter pylori infection. It is considered the best method for epidemiological studies, but there are few studies to evaluate the 13C-UBT in infants and toddlers.

AIM

To evaluate the 13C-UBT performed with infrared spectroscopy in children aged up to 6 years.

PATIENTS

Sixty-eight patients (6 months. to 5 years 11 months.) were evaluated prospectively and consecutively.

METHODS

Helicobacter pylori infection was detected by positive culture, or rapid urease test and histological examination, both positive. 13C-UBT was performed with 50 mg of 13C-urea diluted in 100 ml of commercial orange juice. Two expired air samples were collected: before and 30 minutes after tracer ingestion. Cutoff of delta over baseline (DOB) was 4.0 per thousand and urea hydrolysis rate 10 microg/minute.

RESULTS

Fifteen of 68 (22.1%) patients were H. pylori infected. Sensitivity was 93.3% (95% CI; 86.8%-99.7%) and specificity was 96.2% (95% CI; 93.6%-98.8%), and these values were equal for DOB and urea hydrolysis rate. Negative DOB values in noninfected patients ranged from -1.5 per thousand to 2.6 per thousand and positive DOB values ranged from 10.8 per thousand to 105.5 per thousand. There was no relationship between DOB values and age. Conclusion. 13C-UBT performed with infrared spectroscopy proved to be a reliable and accurate noninvasive diagnostic tool for H. pylori infection detection in children aged up to 6 years. Results far from cutoff value can clearly distinguish positive from negative 13C-UBT results in children up to 6 years old.