An evaluation of whole blood testing for Helicobacter pylori in general practice

Epidemiology of Helicobacter pylori in Australia: a scoping review

Background

Helicobacter pylori (H. pylori), a bacterium implicated in the development of peptic ulcer and gastric cancer, is estimated to infect around half the world's population. Its prevalence in Australia is unclear. This scoping review aimed to evaluate all Australian literature providing estimates of the prevalence of H. pylori.

Methods

Australian studies examining H. pylori prevalence from 1982 onwards were eligible for inclusion. Medline, Embase and Scopus databases, and grey literature sources, were searched. Two independent reviewers undertook a two-stage screening process. Data were extracted by two independent reviewers using a pre-specified template.

Results

Of 444 identified studies, 75 were included in the review. H. pylori prevalence in Australian population-based studies (n = 8) ranged from 38.0% in 1991 to 15.1% in 2002; however, estimated prevalence across all non-clinical population studies in diverse sub-groups (n = 29) has varied dramatically. Decreased prevalence has been more marked in populations with gastrointestinal symptoms and conditions compared to non-clinical populations. Data on H. pyloriprevalence in vulnerable populations are lacking.

Conclusions

This is the first scoping review of Australian studies reporting H. pylori prevalence. A wide range of study designs, population groups, geographic regions, and diagnostic methods was included, involving data collected over a 50-year period (1969 to 2018). The summary of H. pylori prevalence estimates over time in this review points to a decrease in prevalence in Australia, particularly among populations with gastrointestinal symptoms and illnesses; however, it is unknown whether there is inequity in prevalence trends across vulnerable sub-groups of the Australian population. Future research and interventions supporting the health and wellbeing of vulnerable populations is required to ensure equitable health gains are made for all.

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.

Immunoglobulin G antibody against Helicobacter pylori is an accurate test for atrophic gastritis

BACKGROUND

Enzyme-linked immunosorbent assay (ELISA) is the most commonly used serologic test for Helicobacter pylori. This study aimed to investigate the effects of age and atrophic gastritis on the diagnostic accuracy of an immunoglobulin G (IgG) antibody test against H. pylori in adults.

METHODS

One hundred and seventy dyspeptic patients (age range, 20-70 years) were evaluated. H. pylori infection was diagnosed when culture or both urease and histological tests were positive. Serum pepsinogen-I (P-I) and pepsinogen-II (P-II) levels were measured. Atrophic gastritis was defined when P-I < or = 70 microg/L and P-I/P-II < or = 3. A quantitative ELISA test (HEL-pTEST II) was used for IgG antibodies against H. pylori.

RESULTS

The H. pylori prevalence rate was 62.1%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ELISA were 93.5%, 94.4%, 95.6%, 91.9%, and 93.9% in patients aged < 45 years, and 100%, 81.3%, 94.3%, 100%, and 95.6% in patients aged > or = 45 years, respectively. Twenty-six patients had atrophic gastritis. There was 100% sensitivity and 86.7% specificity in atrophic gastritis and 96.5% sensitivity and 91.9% specificity in non-atrophic gastritis.

CONCLUSION

The quantitative ELISA test is a good noninvasive test even in older age groups and is a suitable test in patients with atrophic gastritis due to its excellent sensitivity.

Validation of four Helicobacter pylori rapid blood tests in a multi-ethnic Asian population

AIM: To validate the accuracy of four rapid blood tests in the diagnosis of Helicobacter pylori.

METHODS: Consecutive dyspeptic patients scheduled for endoscopy at the National University Hospital, Singapore, were interviewed and had blood drawn for serology. The first 109 patients were tested with BM-test (BM), Pyloriset Screen (PS) and QuickVue (QV), and the next 99 subjects were tested with PS and Unigold (UG). Endoscopies were performed blinded to rapid blood test results and biopsies were taken for culture and rapid urease test. Urea breath tests were performed after endoscopies. The rapid blood test results were compared with four reference tests (rapid urease test, culture, serology, and breath test).

RESULTS: The study population composed of 208 patients (mean age 43.1 years; range 18-73 years; 119 males; 174 Chinese). The number of evaluable patients for BM, QV, UG and PS were 102, 102, 95, and 197, respectively. The sensitivity and specificity, respectively were: PS 80.2%, 95.8%; UG 55.9%, 100%; QV 43.3%, 100%; BM 67.2%, 97.1%.

CONCLUSION: The rapid blood test kits showed high specificity and positive predictive value (97-100%), while sensitivity and negative predictive value ranged widely (43%-80% and 47%-73%, respectively). Among test kits, PS showed the best sensitivity (80%), best negative predictive value (73%) and best negative likelihood ratio (0.207). PS had a specificity of 96%, positive predictive value of 97% and positive likelihood ratio of 19.1.

Evaluation of two stool antigen tests for the detection of Helicobacter pylori infection in the Chinese population

BACKGROUND AND AIM

The stool antigen test, the HpSA test, has been validated mainly in Western countries, but not properly in the Chinese population. Recently, another stool antigen test, the Apollo test, was developed, but its accuracy has rarely been validated. The aim of this study is to compare the accuracy of these two tests in the diagnosis of Helicobacter pylori infection in the Chinese population.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, biopsies were taken for the rapid urease test and histological examination as the gold standard. Stool specimens were collected and used for the HpSA and Apollo tests.

RESULTS

Overall, 86 patients (39 males and 47 females, with a mean age of 55.8 years) were recruited. Helicobacter pylori infection was present in 44 (51%) patients as determined by the gold standard. The sensitivity, specificity and accuracy were 86.4, 100, and 93.0%, respectively, for the HpSA, and 90.9, 97.6, and 94.2%, respectively, for the Apollo test when cases with equivocal results were considered as positive. In addition, agreement was achieved in 81 (94.2%) cases between the two tests, with a Kappa value of 0.887.

CONCLUSION

Both the HpSA and Apollo tests achieve acceptable sensitivity and excellent specificity, with accuracies of over 90% for the detection of H. pylori infection in the Chinese population.

Accuracy of a new near patient test for the diagnosis of Helicobacter pylori infection in Chinese

BACKGROUND AND AIM

The performance of existing near patient tests for the diagnosis of Helicobacter pylori remains unsatisfactory. The aim of this study is to evaluate the accuracy of a new near patient test (Signify H. pylori) for the diagnosis of H. pylori and the usefulness of the Signify H. pylori test for a test and treat strategy.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. Rapid urease test and histology were used as the gold standard. After endoscopy, blood was collected for the Signify H. pylori test and compared with a gold standard.

RESULTS

Two hundred and forty-four patients were eligible for analysis and 121 (49.5%) were positive for H. pylori. The Signify H. pylori test showed a sensitivity, specificity, and accuracy of 84.3, 89.4%, and 86.9%, respectively, for whole blood and 79.3, 88.6, and 84.0% for serum, respectively. The sensitivity and specificity of the Signify H. pylori whole blood test was 87.5 and 92.6% for patients less than 45-years-old and the accuracy was similar between patients referred from primary care physicians or gastroenterologists. The test is easy to operate and results are available within 5 min.

CONCLUSION

The Signify H. pylori test is accurate for the near patient diagnosis of H. pylori infection.

Immunoglobulin G antibody against Helicobacter pylori: clinical implications of levels found in serum

The clinical significance of high levels of antibody against Helicobacter pylori is still unclear. We sought to evaluate whether the serum antibody levels could predict the presence of macroscopic gastroduodenal disease, to identify factors that correlate with antibody levels in a multivariate context, and to determine the predictive value of antibody levels for diagnosing H. pylori infection. The grades of gastritis and density of H. pylori colonization were scored separately using the updated Sydney system for antral and body mucosa. An enzyme-linked immunosorbent assay (ELISA) for the quantitative detection in serum of IgG antibodies to H. pylori was performed. Of the 170 dyspeptic patients, 105 (62%) had H. pylori infection. There was no difference in antibody levels among endoscopic findings of normal mucosa, chronic gastritis, and duodenal ulcer. On multivariate linear regression analysis, the status of H. pylori infection, mononuclear cell infiltration of body mucosa, and age correlated with antibody levels. The negative predictive value for antibody levels of <30 U/ml is 94%, and the positive predictive value of antibody levels of >70 U/ml is 98%. We conclude that serum antibody levels do not predict the severity of gastroduodenal diseases or the density of H. pylori colonization in H. pylori-infected dyspeptic patients. Higher levels are associated with the presence of H. pylori infection, the chronic gastritis score of the corpus, and older age. Setting a gray zone is necessary for ELISA, since the accuracy in this zone does not allow a precise determination of H. pylori status.

Accuracy of office-based immunoassays for the diagnosis of Helicobacter pylori infection in children

BACKGROUND

Rapid non-invasive diagnostic tests that can reliably document the presence or absence of Helicobacter pylori infection are urgently required. The aim of this study was to determine the accuracy of two immunoassays (Flex-Sure and MedMira), developed for use outside the laboratory setting by practitioners, in the setting of a low prevalence of H. pylori infection.

METHODS

Serum samples collected in four previous studies (n = 349) were employed to detect the presence of H. pylori-specific immunoglobulin G, compared to previous results obtained using endoscopic biopsies, serology, flow cytometry, and urease breath testing. Serum samples included 52 obtained from adults (parents and grandparents of symptomatic children), 123 sera collected from children and adolescents undergoing diagnostic upper endoscopy for upper gastrointestinal tract symptoms, and 174 samples drawn from children in the primary care setting with or without recurrent abdominal pain.

RESULTS

Overall, 16% of subjects were infected by the gastric pathogen. Both the specificity (%) and negative predictive value (%) of the two tests were high (FlexSure: 91 and 92; Medmira: 97 and 94, respectively). In adults, both tests also demonstrated high sensitivity (83% and 86%) and positive predictive values (79% and 83%, respectively). However, in children where the prevalence of infection was 12% (37 of 297 subjects), the sensitivity (59% and 71%) and positive predictive values (55% and 88%, respectively) of the immunoassays were lower.

CONCLUSIONS

These findings indicate that, in the setting of a low prevalence of H. pylori infection, the MedMira office-based test provides satisfactory results and utility. However, the low positive-predictive value of the FlexSure kit may limit applicability of this test in children.

Optimal serological tests for the detection of Helicobacter pylori infection in the Chinese population

BACKGROUND

Numerous serological tests for the detection of Helicobacter pylori infection have been developed. However, many perform poorly when evaluated in the Chinese population.

AIM

To search for optimal serological tests for the detection of H. pylori infection in Chinese patients.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, gastric biopsies were taken for the CLOtest and histological examination. Patients were then given a 13C-urea breath test. Sera were used to test for H. pylori infection, employing three commercial enzyme-linked immunosorbent assay kits (pylori DTect, HP IgG and GAP IgG). Results were compared with the gold standard defined by the CLOtest, histology and 13C-urea breath test.

RESULTS

Among the 142 patients (47 male, 95 female; mean age, 49 years) recruited, 81 (57%) were H. pylori-positive, 57 (40%) were H. pylori-negative and four (3%) were defined to be indeterminate. Using a self-defined cut-off value after calculation, the best accuracies for the pylori DTect, HP IgG and GAP IgG tests were 97%, 91% and 80%, respectively.

CONCLUSIONS

The pylori DTect test is an optimal serological test for the detection of H. pylori infection in Hong Kong Chinese patients. The HP IgG test may be used as an alternative.

[Study of the validity of "rapid" serology in diagnosing Helicobacter pylori infection]

OBJECTIVE

To evaluate prospectively the validity of a <<rapid>> serology diagnosis method (using capillary blood) in our ambit, taking for reference a combination of standard diagnostic methods.

DESIGN

Prospective. The endoscopist, pathologist and those responsible for interpreting the rapid urease test, the breath test and <<rapid>> serology did not know the results of the other diagnostic methods.

SETTING

Gastro-enterology service of a tertiary hospital.Participants. 30 consecutive patients with symptoms attributable to the upper digestive tract and who underwent an oral gastroscopy. Main measurements. Gastric biopsies for histology examination and for the rapid urease test and a breath test with 13C-urea were conducted. For <<rapid>> serology, the commercial SureStep HP WB test kit was used. A patient was considered infected when at least two of the three validated techniques (rapid urease test, histology, breath test) were positive; and not infected, when all three were negative.

RESULTS

30 patients, 30% male, with a mean age of 51, were included. The reference standard indicated 61% prevalence of infection, with two cases classed as undetermined. <<Rapid>> serology was positive in 8 patients and negative in 22. Sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 41% (95% CI, 18-65), 91% (74-100), 87% (65-100) and 50% (28-72). The positive probability quotient was 4.5; and the negative, 0.65.

CONCLUSION

The <<rapid>> serology used in the current study has deficient diagnostic accuracy. Therefore, it should not be used in clinical practice to identify H. pylori infection.

Extending the reading time increases the accuracy of rapid whole blood test for diagnosis of Helicobacter pylori infection

BACKGROUND

To evaluate the accuracy of two rapid whole blood tests (the BM-Test Helicobacter pylori and the QuikPac IV One Step H. pylori Whole Blood Test), and compare this to a conventional quantitative ELISA test (HEL-p TEST II).

METHODS

Helicobacter pylori status in dyspeptic patients was assessed by culture, histology, and rapid urease tests on biopsies from the antrum and corpus. The optimal cut-off value of the reading time for the rapid blood tests was determined by using the receiver characteristics operative (ROC) curves.

RESULTS

In the 141 patients examined, 89 were infected, 51 were not infected, and one was indeterminate (only positive in either urease test or histology). Areas under ROC curves were greater in the BM-Test compared with the QuikPac IV (0.948 vs 0.840, P < 0.01), with their most appropriate cut-off reading times at 360 and 395 min, respectively, rather than 10 min as suggested by the manufacturer. The sensitivity and specificity were 94.4% and 94.1% at 360 min, and 74.2 and 96.1% at 10 min for the BM-Test; 80.9, 76.5 at 395 min and 3.4 and 100% at 10 min for the QuikPac IV. The antibody titer of the quantitative ELISA test was negatively correlated with the reaction time of the two rapid blood tests in H. pylori-infected patients (P < 0.05, r=-0.3).

CONCLUSIONS

The BM-Test is an appropriate office-based test for diagnosing H. pylori infection in Chinese patients. Extending the reading time would facilitate the readability of rapid blood tests with a resultant increase in accuracy.

Care of the elderly with gastrointestinal problems in family practice

Gastrointestinal problems in older people cause a great amount of anxiety, morbidity and mortality. In general these diseases present for the first time to family practitioners. The management of gastrointestinal problems is more difficult because in an older age group, functional diseases can present in the same way as organic diseases. In addition, family practitioners see a different kind of patient than speciality physicians and may not have immediate access to diagnostic investigations. In this chapter, the role of the family practitioner in screening for gastrointestinal problems in asymptomatic older people is explored. In addition, how they differentiate between organic and non-organic disease and refer appropriately to secondary care is discussed. The role of family practitioners in the on-going maintenance of gastrointestinal diseases and in the management of Helicobacter pylori in community dwelling older people is also considered.

Review article: managing the dyspeptic patient--an interactive discussion

Dyspepsia, a common disorder, can present some difficult clinical dilemmas. Physicians should explore some of the more challenging cases of dyspepsia in a setting that fosters interactive dialogue among colleagues, as was the case at the interactive discussion reported below. A panel of experts presented and discussed three case histories. The audience was able to choose from among several options for diagnosis or treatment and recorded their votes by means of an electronic handset. The first case concerned the relationship between continued non-steroidal anti-inflammatory drug (NSAID) use and recurrent upper gastrointestinal (GI) symptoms without ulcer or Helicobacter pylori infection. The second was a woman with complex upper GI symptoms including heartburn. The last featured a young man with dyspepsia and no alarm symptoms. The first case showed that a standard dose of proton pump inhibitor (PPI) is the best treatment for patients with gastritis who continue to use NSAIDs. The second case revealed that 24-h pH monitoring can be used to establish a relationship between symptoms and reflux episodes. The third case demonstrated that it can be difficult to make a definitive diagnosis based on clinical symptoms, and that patients with endoscopy-negative reflux disease usually respond well to PPI therapy.

Helicobacter pylori testing in the primary care setting: which diagnostic test should be used?

AIM

To identify the most accurate and efficient test for diagnosing Helicobacter pylori infection in primary care patients.

STUDY DESIGN

A whole blood test, an ELISA, and carbon13 urea breath test (CUBT) were evaluated in a primary care setting and validated against two different gold standards that used gastric biopsies.

POPULATION

Primary care patients who had dyspeptic complaints lasting at least 2 weeks and were referred for endoscopy.

OUTCOMES MEASURED

Positive and negative predictive values, sensitivity and specificity were determined for all three noninvasive H. pylori tests.

RESULTS

Data from the three non-invasive H. pylori tests were available for 136 primary care dyspeptic patients referred for endoscopy. They were compared with data from the gold standards. The positive predictive value of the whole blood test was in the range 71-75%, the ELISA 83-86%, and the CUBT 88-92%, while the negative predictive values were in the ranges 72-77%, 96-100%, and 95-98%, respectively. The sensitivity of the whole blood test was in the range 36-42%, the ELISA 93-100%, and the CUBT 92-97%, while the specificities were in the ranges 92-93%, 90-91% and 93-95%, respectively. The positive predictive value of the ELISA dropped significantly at lower H. pylori infection rates.

DISCUSSION

Both the ELISA and CUBT are effective in the primary care setting, while the whole blood tests produces inferior results. ELISA might, however, be less suitable for detecting H. pylori infection in a population with a low rate of infection.

Development and clinical application of an immunoassay using intact Helicobacter pylori attached to a solid phase as an antigen

OBJECTIVE

At present, H. pylori homogenates, extracts and recombinant proteins are used as antigens in immunoassays, but significant false positive and negative results are obtained. We attempted to develop an ELISA system using immobilized whole intact H. pylori cells as a solid phase antigen (WIC-ELISA) which specifically recognizes surface antigens.

METHODS

Intact H. pylori cells were immobilized on ELISA plates by centrifugation (150 g for 10 min). HRP-labeled antihuman IgG was used as the second antibody. H. pylori-infections were investigated with WIC-ELISA and a conventional method in which H. pylori-extracts were used as antigen in 117 patients.

RESULTS

WIC-ELISA showed better characteristics than conventional ELISA in regards to sensitivity (98.9 vs. 90.4%), specificity (95.7 vs. 95.7%), positive predictive value (98.9 vs. 98.8%), negative predictive value (95.7 vs. 71.0%) and accuracy (98.3 vs. 91.5%).

CONCLUSIONS

WIC-ELISA is useful for quantification of antibodies against H. pylori surface antigens and as a clinical screening test.

[Diagnosis of Helicobacter pylori infections]

Hardly any other bacterial infection can be diagnosed with a similar variety of non-invasive and invasive tests as infection with H. pylori. Efficacy and specificity of well-proven tests such as urease test in biopsy specimens, histology, culture, and 13C breath test have been uniformly evidenced in numerous studies. Novel tests include molecular microbiological procedures, providing new opportunities for rapid detection of virulence factors and resistance genes, as well as antigen detection in feces. Though some open questions still need to be clarified, the latter test will gain major importance in the future. With the availability of the breath test and antigen detection in stool the need for the use of serological tests has been reduced, all the more so as the majority of the available quick tests have been shown to be of inadequate reliability. Well defined indications for the treatment of H. pylori infections are a major prerequisite for a reasonable use of this diagnostic armory.

The cost-effectiveness of diagnostic testing strategies for Helicobacter pylori

OBJECTIVE

Several noninvasive methods are now available for diagnosing Helicobacter pylori infection. Because the prevalence of H. pylori infection is variable in patients requiring testing, the optimal testing strategies may vary under different conditions. The aim of this study was to evaluate the cost-effectiveness of competing diagnostic strategies for H. pylori in patients with varying H. pylori prevalence.

METHODS

A decision analysis was performed comparing the costs per number of correct diagnoses achieved by alternative sequential testing strategies. Estimates of H. pylori prevalence and test characteristics were derived from a systematic review of the MEDLINE bibliographic database. Cost estimates were derived from the 2000 Medicare Fee Schedule.

RESULTS

The enzyme-linked immunosorbent assay (ELISA) test had the lowest cost per correct diagnosis at low (30%), intermediate (60%), and high (90%) prevalence ($90-$95/correct diagnosis), but its diagnostic accuracy was low (80-84%). At low and intermediate prevalence the stool test was more accurate (93%), with an average cost of $126-$127 per correct diagnosis. Additional confirmatory testing of positive or negative tests increased the diagnostic accuracy of the stool test, but had high incremental costs. ELISA testing was preferable when prevalence rates were very high (90%), and using a confirmatory urea breath test for negative ELISA tests increased the diagnostic accuracy to 96%, with modest incremental costs. If the cost of the breath test was <$50 or if the cost of the stool test is >$82, breath testing became preferable to stool testing. If the cost of the stool test fell to <$20, it became preferable to ELISA. Similarly, if the cost of the ELISA serology was >$39 then stool testing became preferable at all prevalence rates. Fingerstick whole blood tests were not cost-effective.

CONCLUSIONS

The choice of an initial test for H. pylori detection depends on the prevalence of H. pylori infection and the value placed on increased diagnostic accuracy. Although ELISA results in the lowest cost-effectiveness ratios, in patients at low-intermediate pretest probability of infection, the stool test provides increased accuracy, with modest incremental costs.

Testing for Helicobacter pylori infection: validation and diagnostic yield of a near patient test in primary care

OBJECTIVE

To evaluate the performance of a near patient test for Helicobacter pylori infection in primary care.

DESIGN

Validation study performed within a randomised trial of four management strategies for dyspepsia.

SETTING

43 general practices around Nottingham.

SUBJECTS

394 patients aged 18-70 years presenting with recent onset dyspepsia.

MAIN OUTCOME MEASURES

Results of the FlexSure test compared with an enzyme linked immunosorbent assay (ELISA; HM-CAP) with an identical antigen profile and with results of an earlier validation study in secondary care. Diagnostic yield of patients undergoing endoscopy on the basis of their FlexSure result compared with those of patients referred directly for endoscopy.

RESULTS

When used in primary care FlexSure test had a sensitivity and specificity of 67% (95% confidence interval 59% to 75%) and 98% (95% to 99%) compared with a sensitivity and specificity of 92% (87% to 97%) and 90% (83% to 97%) when used previously in secondary care. Of the H pylori test and refer group 14% (28/199) were found to have conditions for which H pylori eradication was appropriate compared with 23% (39/170) of the group referred directly for endoscopy.

CONCLUSIONS

When used in primary care the sensitivity of the FlexSure test was significantly poorer than in secondary care. About a third of patients who would have benefited from H pylori eradication were not detected. Near patient tests need to be validated in primary care before they are incorporated into management policies for dyspepsia.

Systematic review of near patient test evaluations in primary care

OBJECTIVE

To identify and qualitatively synthesise the findings from all studies that have examined the performance and effect of near patient tests in the primary care setting.

DESIGN

Systematic review of published and unpublished research 1986-99.

MAIN OUTCOME MEASURES

Test performance characteristics, measures of effect on clinical practice or patient outcome.

RESULTS

101 relevant publications were identified. The general quality of these papers was low, and consequently only 32 papers were assessed in detail. Although these papers gave some indication of the value of near patient testing in areas such as anticoagulation monitoring and group A beta haemolytic streptococcus testing, the research raised many more questions than it answered. Almost no reports were found of unbiased assessment of the effect of near patient tests in primary care on patient outcomes, organisational outcomes, or cost.

CONCLUSIONS

Available research provides little evidence to guide the expansion of use of near patient testing in primary care. Further research is needed in areas of clinical practice where near patient tests might be most beneficial.

Development of a new dyspepsia impact scale: the Nepean Dyspepsia Index

BACKGROUND

There is not at present a suitable disease-specific health-related quality of life instrument for uninvestigated dyspepsia and functional (non-ulcer) dyspepsia.

AIM

To develop a new multi-dimensional disease-specific instrument.

METHODS

The Nepean Dyspepsia Index (NDI) was designed to measure impairment of a subject's ability to engage in relevant aspects of their life and also their enjoyment of these aspects; in addition, the individual importance of each aspect is assessed. A 42-item quality of life measure was developed and tested, both in out-patients presenting to general practice with upper gastrointestinal complaints (n = 113) and in a randomly chosen population-based sample (n = 347).

RESULTS

Adequate face and content validity was documented by an expert panel. Factor analysis identified four clinically relevant subscales: interference with activities of daily living, work, enjoyment of life and emotional well-being; lack of knowledge and control over the illness; disturbance to eating or drinking; and disturbance to sleep because of dyspepsia. These scales had high internal consistency. Both symptoms and the quality of life scores discriminated dyspepsia from health.

CONCLUSION

The Nepean Dyspepsia Index is a reliable and valid disease-specific index for dyspepsia, measuring symptoms and health-related quality of life.