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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Summary

Background

Assessment of symptoms should be the primary outcome measure in dyspepsia clinical trials. This requires a reliable, valid and responsive questionnaire that measures the frequency and severity of dyspepsia. The Leeds Dyspepsia Questionnaire fulfils these characteristics, but is long and was not designed for self-completion, so a shorter questionnaire was developed (the Short-Form Leeds Dyspepsia Questionnaire).

Aim

To assess the acceptability, interpretability, internal consistency, reliability, validity and responsiveness of the Short-Form Leeds Dyspepsia Questionnaire in primary and secondary care.

Methods

Unselected primary and secondary care patients completed the Short-Form Leeds Dyspepsia Questionnaire. Test–retest reliability was assessed after 2 days. Validity was measured by comparison with general practitioners’ diagnosis. Sensitivity analysis and logistic regression were employed to determine the most valid scoring system. Responsiveness was determined before and after treatment for endoscopically proven disease.

Results

The Short-Form Leeds Dyspepsia Questionnaire was administered to 388 primary care and 204 secondary care patients. The Pearson coefficient for test–retest reliability was 0.93. The Short-Form Leeds Dyspepsia Questionnaire had a sensitivity of 77% and a specificity of 75%. A highly significant response to change was observed (P < 0.005).

Conclusions

The Short-Form Leeds Dyspepsia Questionnaire is a reliable, valid and responsive self-completed outcome measure for quantifying the frequency and severity of dyspepsia symptoms, which is shorter and more convenient than the Leeds Dyspepsia Questionnaire.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Dyspepsia is a common condition, and one that consumes considerable resources in both investigation and treatment and of which there is still a great deal of uncertainty regarding its management.1, 2 As a result, a number of ‘cost-effectiveness’ randomized trials of dyspepsia management strategies have been conducted. One difficulty for researchers has been choosing an appropriate outcome measure as definitions of dyspepsia have changed over the years, and cost-effectiveness studies require that the ‘effect measure’ is not contaminated by ‘resource use questions’ such as visits to a doctor. Multidimensional scales that also assess quality of life are particularly problematic, as there are better validated quality of life measures that have generalizability over other disease areas (e.g. Health Utility Index3 and EQ-5D4). As there is no ‘absolute’ definition of dyspeptic symptoms we rely on questionnaires that have established psychometrics.5 Dyspepsia symptoms can be assessed by measuring either frequency or severity. The frequency of symptoms has been found to correlate more closely with a clinical diagnosis of dyspepsia than severity, indicating that frequency may be more valid for pragmatic studies.6 In gastro-oesophageal reflux disease (GERD), severity of symptoms correlates more closely with oesophagitis cure than frequency, indicating that severity may be more responsive to change.7 Measuring both frequency and severity of dyspepsia symptoms may improve both validity and responsiveness to change of an instrument compared with measuring either alone.6–9 A final important factor for cost-effectiveness trials is that the instrument is suitable for self-completion by the subject, in terms of length and ease of comprehension.

For clinical trials based in a primary care setting, the outcome measure should have been validated in a primary care population, where the aetiology, prevalence and severity of patients’ symptoms may differ to those from secondary or tertiary care populations.10

In addition, outcome measures should be able to distinguish between patients suffering from predominantly ulcer-like symptoms (epigastric pain) or reflux symptoms (heartburn and regurgitation); some evidence suggests that predominant ulcer-like or reflux symptoms do not reliably predict endoscopic diagnosis of oesophagitis or ulcer, respectively.11

In a recent review of symptom-based outcome measures for dyspepsia and GERD trials 37 studies were identified describing 26 questionnaire outcome measures.5 Twelve assessed symptoms only, and 14 were multidimensional. Of the unidimensional questionnaires, only two assessed both frequency and severity of dyspepsia and had proven reliability, validity and responsiveness. The Reflux Disease Diagnostic Questionnaire (RDQ) is an excellent measure for GERD, but is not validated to assess dyspepsia.11 The Leeds Dyspepsia Questionnaire (LDQ)10 was the only fully validated unidimensional instrument to assess both frequency and severity of dyspepsia symptoms. Although the LDQ is a useful unidimensional outcome measure for dyspepsia, it has three main disadvantages. It is researcher administered (not self-completed), it is long (nine pages) and has a long reference time frame (6 months). The aim of this study was to validate a shortened and revised the LDQ as a suitable measure for dyspepsia trials.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Questionnaire development

The Short-Form Leeds Dyspepsia Questionnaire (SF-LDQ) was developed by shortening and revising the previously validated LDQ.10 The LDQ contained eight questions relating to dyspeptic symptoms, and one question about the most troublesome symptom for the patient. The SF-LDQ contained the four questions from the LDQ which had the greatest validity compared with dyspepsia diagnosis by general practitioners (GP) and gastroenterologists.12 Each question comprised two stems concerning the frequency and severity of each symptom during the last 2 months. This time frame was a balance between reducing recall bias (requiring a shorter time frame) and maximizing data capture without unnecessary respondent burden (requiring a longer time frame).9 The SF-LDQ also contained a single question concerning the most troublesome symptom experienced by the patient to enable categorization of patients on the basis of predominant heartburn or epigastric pain.

The SF-LDQ was redesigned to increase its acceptability, interpretability and feasibility of self-completion. The questions were arranged to fit onto a single A4 page, with shaded boxes around the questions and tick boxes for responses. Short summaries of the symptoms were included to reduce ambiguity, and diagrammatic representations of epigastric pain and heartburn were added to ensure understanding of these symptoms.

The SF-LDQ was piloted initially using six rounds of peer review and feedback. Version 6 of the questionnaire was piloted using a sample of 67 consecutive primary care patients. Several modifications of the format were made and instructions were included on the questionnaire as a result. The final version of the SF-LDQ is attached (Figure 1).

image

Figure 1.  The Short-Form Leeds Dyspepsia Questionnaire (SF-LDQ).

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Evaluation of the SF-LDQ

The characteristics of the questionnaire were examined using patient populations in both primary care, with a relatively low prevalence of disease, and secondary care, with a high prevalence of dyspepsia. The primary care population consisted of consecutive patients aged 18–65, presenting to two inner city general practices in Birmingham (deprivation ranks of 386 and 841 of 32 48213) with any condition. As dyspeptic symptoms affect around 28% of the population,14, 15 we did not specifically select patients with dyspepsia. The secondary care study population consisted of unselected patients aged 18 and over, attending for endoscopy at the Leeds General Infirmary. Patients were excluded if they were incapable of giving informed consent, or if they could not speak or read English.

Patients were asked to participate in the study on arrival at their GP's surgery or the endoscopy suite. A trained researcher obtained informed consent. Patients self-completed the SF-LDQ and an assessment sheet containing questions about the acceptability and interpretability of the questionnaire. These were sealed in an envelope before seeing the GP or gastroenterologist, who made a blind assessment of the whether the patient suffered with dyspepsia and recorded this on the preprinted envelope along with demographic information. Validity was established by comparing the SF-LDQ score with the presence or absence of dyspepsia as diagnosed by the GP or gastroenterologist.

All primary care participants were asked to complete a second SF-LDQ after 2 days to assess test–retest reliability. Within the secondary care population, patients identified as having oesophagitis or peptic ulcer disease during endoscopy were asked to complete a second SF-LDQ 2 months later after receiving treatment of proven efficacy (proton pump inhibitor therapy and/or Helicobacter pylori eradication therapy). This enabled assessment of the SF-LDQ's responsiveness to change in conditions with evidence-based treatments. Freepost envelopes were used to enhance response rates, but non-responders to the second questionnaire were not contacted.

Data were entered onto Microsoft Excel 2000 before conversion into SPSS Inc., Chicago, IL, USA, v10 for analysis. Logistic regression analysis was performed using Generalized Linear Interactive Modelling, Royal Statistical Society (GLIM) to determine the most valid scoring system for the questionnaire. Statistical significance was determined where P < 0.05. Ethical approval was obtained for South Birmingham, West Birmingham and Leeds, UK.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Population

A total of 592 patients were enrolled into the study, 388 patients from primary care and 204 patients from secondary care. Out of these, 361 (61%) were female and 231 (39%) were male. Ages for the primary care patients ranged from 18 to 65, and for secondary care, 18–81. Fifty-five questionnaires (9%) had one or more missing responses and were excluded from the final analysis, as a summed score could not be calculated. Score analysis was therefore performed on 375 patients from primary care and 162 patients from secondary care.

Interpretability and acceptability

Five hundred and eighty-six participants from primary and secondary care completed at least one question concerning the interpretability and acceptability of the SF-LDQ. Overall, 97% found the questionnaire easy to read, 95% found it easy to interpret and 94% thought the layout was sufficiently clear.

Endorsement frequencies (the proportion of respondents who chose each response category to a question) were calculated for each response category to every question using combined data from primary and secondary care. Every response category had an endorsement frequency of >5%, except for regurgitation severity ‘more than daily’ (Table 1). The distribution of responses to each of the questions about symptom frequency and severity were positively skewed, reflecting the inclusion of the 278 participants from primary care (47% of all participants) who did not have dyspepsia according to their GPs diagnosis.

Table 1.   Endorsement frequencies for each response category of the Short-Form Leeds Dyspepsia Questionnaire
SymptomResponse category (%)
Not at allLess than monthlyBetween monthly and weeklyBetween weekly and dailyMore than dailyNo response
Indigestion frequency35161516171
Heartburn frequency39181515130.8
Regurgitation frequency4321141480.5
Nausea frequency3823161491
Indigestion severity4512131685
Heartburn severity5011151275
Regurgitation severity5613121045
Nausea severity4618121166

Non-response to questions regarding symptom frequency occurred with 1% or less of participants, indicating that this part of the questionnaire was acceptable and interpretable. However, there was no response to questions regarding symptom severity in around 5% of cases, indicating that this part of the questionnaire may have been less acceptable or interpretable.

Internal consistency

Cronbach's alpha coefficient for combined primary and secondary care patients was 0.90, representing a high level of internal consistency. The item-total correlation for each question ranged from 0.57 to 0.75, suggesting that each question was independently associated with the total questionnaire score and that all questions were measuring different aspects of the same condition.

Test–retest reliability

In the primary care sample, 151 of 375 patients (40%) returned a fully completed second questionnaire after at least 2 days. Pearson's correlation coefficient between the first and second summed total scores was 0.93, representing a high degree of reliability on re-testing the questionnaire.

Validity

Concurrent validity was established using the primary care population and divergent validity was examined by comparing the primary and secondary care populations.

Concurrent validity

Concurrent validity was assessed by comparing the SF-LDQ score with the GPs’ opinion of whether the patient had dyspepsia, expressed as a dichotomous ‘yes’ or ‘no’ response. Altogether 101 patients (27%) were diagnosed as suffering with dyspepsia, 278 patients (73%) had no dyspepsia. Nine participants out of 375 with fully completed questionnaires did not receive a clinical assessment of dyspepsia by their GP, so 366 primary care patients were analysed to determine concurrent validity.

Sensitivity analyses

SF-LDQ scores were calculated using five different methods to evaluate which produced the most valid assessment of dyspepsia. These methods were:

  • 1
    a summed total score of the frequency and severity responses for each symptom (range: 0–32);
  • 2
    a summed score of the frequency responses for each symptom (range: 0–16);
  • 3
    a summed score of the severity responses for each symptom (range: 0–16);
  • 4
    a categorized score of the single most frequent symptom (range: 0–4) and
  • 5
    a categorized score of the single most severe symptom (range: 0–4).

Categorized scores were calculated by rating the single most frequent or severe symptom from 0 (not at all) to 4 (once a day or more). Scoring systems 1–3 are more practical and feasible to administer as they require simple addition. Scoring systems 4 and 5 are more complex, but may be more valid as they are based on the Rome criteria for assessing the presence of dyspepsia.16

For each scoring system, a Receiver Operating Characteristics (ROC) curve was plotted against the GPs’ diagnosis to determine the most sensitive and specific point on the scale. The first point on each ROC curve where sensitivity was greater than specificity was selected as the ‘cut-off’ for diagnosing the presence of dyspepsia. This gave a dichotomous outcome of whether dyspepsia was present or absent for each scoring system. Table 2 shows the area under the ROC curves and their 95% confidence intervals (CIs) using different scoring systems, together with the chosen cut-off score, sensitivity and specificity for that system.

Table 2.   Attributes of the five systems used to score the Short-Form Leeds Dyspepsia Questionnaire in the primary care population
Scoring systemArea under curve (95% CI)‘Cut-off’ scoreSensitivitySpecificity
1 Summed total score0.82 (0.777–0.868)7/3277.373.2
2 Summed frequency score0.83 (0.790–0.876)4/1686.066.2
3 Summed severity score0.76 (0.700–0.817)2/1680.661.0
4 Categorized frequency score0.79 (0.738–0.836)2/486.159.7
5 Categorized severity score0.73 (0.671–0.787)1/484.245.7

Although the summed frequency score produced a slightly larger area under the ROC curve (0.83) compared with the summed total score (0.82), this difference was not statistically significant. The summed total score was chosen as the preferred method of scoring the questionnaire because this scoring system had the greatest specificity, giving closer agreement between the sensitivity and specificity, and it also had a greater range of possible scores, allowing greater precision.17Figure 2 shows the ROC curve for the summed total score.

image

Figure 2.  Receiver Operating Characteristic curve for the summed total score of the Short-Form Leeds Dyspepsia Questionnaire. The lines show the most sensitive and specific cut-off point for the scoring system.

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Logistic regression analyses

Logistic regression analyses assessed the strength of the scoring system's association with the GPs’ diagnosis. All associations were strongly statistically significant (P < 0.0005). The summed frequency score was marginally the best predictor of GPs’ diagnosis. However, the difference between the summed total score and the summed frequency score again was not statistically significant.

Discriminant validity

Discriminant validity was assessed by comparing the primary and secondary care populations using the summed total scoring system. Figure 3 shows the range of scores in the two populations. The difference between these scores was highly statistically significant using the Mann–Whitney U-test (P < 0.0005), demonstrating that the SF-LDQ was able to discriminate between two populations with different prevalence of dyspepsia.

image

Figure 3.  Box plot showing the distribution of Short-Form Leeds Dyspepsia Questionnaire summed total scores for primary (n = 375) and secondary care (n = 162) populations. ‘Boxes’ show 25–75th centiles, with the horizontal line representing the mean. ‘Whiskers’ represent the 5th and 95th centiles.

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Responsiveness to change

Oesophagitis or peptic ulcers was found in 60 of the 162 patients who completed the first questionnaire from the secondary care population following endoscopy. These patients were asked to complete a second questionnaire following treatment of proven efficacy, 2 months after the endoscopy. This questionnaire was returned by 47 patients (78%). Ten patients were excluded due to missing data, leaving 37 patients eligible for this analysis.

The number of patients with dyspepsia present and absent according to the ‘cut-off’ identified by the sensitivity analysis for the summed total score (seven of 32) was compared before and after treatment (Table 3). Before treatment 89% of patients had dyspepsia compared with 38% after treatment, which was highly significant using the McNemar test (P < 0.005). The standardized response mean for this change was 1.1, suggesting a large degree of responsiveness.

Table 3.   Number of secondary care patients with dyspepsia before and after treatment using the summed total score (n = 37; ‘cut-off’ point = 7 of 32)
 After treatmentTotal
Dyspepsia presentDyspepsia absent
  1. Values in bold indicate those partipants who had a change in dyspepsia status following treatment. No patients without dyspepsia developed symptoms following treatment, and 19 patients with dyspepsia were ‘cured’ following treatment. This demonstrates that the questionnaire is responsive to changes in symptoms.

Before treatment
 Dyspepsia present141933
 Dyspepsia absent044
Total142337

Predominant symptom analysis

The influence of the predominant (or most troublesome) symptom on the GPs’ diagnosis of dyspepsia and SF-LDQ scores (total and summed frequency) was assessed in the 364 primary care patients who completed this question and had a GP diagnosis. Four subgroups were identified reflecting the 1988 Working Party definition of dyspepsia:18 those with predominant reflux-like symptoms (heartburn and regurgitation); those with predominant ulcer-like symptoms (epigastric pain); those with predominant dysmotility-like symptoms (nausea) and those with no predominant symptom. The results are shown in Table 4.

Table 4.   General practitioner (GP) diagnosis and Short-Form Leeds Dyspepsia Questionnaire scores by symptom subgroup
Symptom subgroupNumber of patientsGP diagnosis (percentage with dyspepsia)Mean total score
Reflux-like924811.4
Ulcer-like595310.7
Dysmotility-like97207.9
None of these11621.1
All patients364267.1

The reflux-like and ulcer-like subgroups contained a higher proportion of patients who were diagnosed with dyspepsia by their GP and had higher mean questionnaire scores compared with the other subgroups. There was little difference between the dyspepsia diagnoses or questionnaire scores of those with predominant reflux-like or ulcer-like symptoms, suggesting that differentiating between these subgroups may not be clinically relevant. There were insufficient numbers of patients in each subgroup to determine the concurrent validity of the questionnaire scores compared with GPs diagnosis using ROC curves. As a result, the sensitivity and specificity of the SF-LDQ for dyspepsia in these subgroups could not be calculated.

The effect of excluding patients with predominant reflux-like symptoms on the concurrent validity of the SF-LDQ was assessed, to determine the effect of using the Rome II definition instead of the 1988 Working Party definition of dyspepsia. This gave an area under the ROC curve of 0.83 for the summed frequency score, which was almost identical to the area under the curve for all patients, including those with predominant reflux symptoms (0.82). This suggests that the SF-LDQ predicts the diagnosis of dyspepsia in a similar way whether or not patients with predominant reflux symptoms are included.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

The SF-LDQ proved to be a sensitive and specific measure, acceptable to patients and suitable for high rates of self-completion. The SF-LDQ was responsive to change and able to differentiate between populations with differing prevalence, demonstrating discriminant validity. Other dyspepsia questionnaires have also been tested for discriminant validity19–21 providing additional evidence for the construct validity of this instrument.

The summed frequency scoring system demonstrated the greatest concurrent validity when analysed using the area under ROC curves and logistic regression. However, the difference in concurrent validity between this scoring system and the summed total score was not statistically significant. The summed total score has a greater range of values (0–32) than the summed frequency score (0–16), which gives greater precision. Rates of non-response to questions about symptom frequency were very low (0.5–1%), indicating that these questions were acceptable. Rates of non-response to questions about symptom severity were higher (5–6%) indicating that these items were less interpretable or acceptable to a minority.

The LDQ has previously demonstrated a sensitivity of 80% (95% CI: 65–91%) and a specificity of 79% (95% CI: 66–89%) in a primary care population.10 These values were marginally higher than the SF-LDQs sensitivity of 77% (95% CI: 68–85%) and specificity of 73% (95% CI: 68–78%) using the summed total score. However, this difference is not statistically significant, and even if the SF-LDQ was slightly less valid than the LDQ, this would be offset by the increased acceptability, feasibility and reliability of the shorter self-completed measure.17 The SF-LDQ had a high level of internal consistency when tested by Cronbach's alpha coefficient and the item-total correlation method, indicating that all of the questions in the questionnaire scale were measuring the same underlying construct, producing a high level of reliability. The SF-LDQ had a higher score for Cronbach's alpha coefficient (0.90) than the LDQ (0.69),10 suggesting that the shorter form was more accurately measuring a single construct.

Assessment of concurrent validity involves comparing the questionnaire against a ‘gold standard’. As there is no ‘gold standard’ for diagnosis of dyspepsia6, 22, 23 a GPs’ diagnosis was chosen as a quasi-gold standard. Validity has been established compared with a clinician's diagnosis in previous studies,10, 19, 24–27 whilst other studies of dyspepsia outcome measures have used different ‘gold standard’ comparisons to demonstrate concurrent validity, such as generic quality of life scores,28–33 patient self-assessment using diaries34 and dyspepsia adverse events.35 An alternative approach would have been to compare the SF-LDQ with the LDQ as the gold standard.17 However, the correlation between the two questionnaires would have been artificially inflated by the presence of four identical questions. No attempt was made to standardize GPs’ diagnosis through discussion of the 1988 Working Party definition of dyspepsia with them.18 Standardizing the GPs’ diagnosis in this way would have artificially increased the concurrent validity of the SF-LDQ, because the questionnaire is based upon the Working Party definitions.

It should be emphasized that the SF-LDQ is designed as an outcome assessment tool and not as a diagnostic tool. Although considerable effort has been made by the Rome process to disentangle reflux and epigastric pain, this has not been successful where patients have not had endoscopic investigation to exclude peptic ulcer and oesophagitis. Exclusion of patients with predominant reflux-like symptoms did not substantially alter the concurrent validity of the SF-LDQ, when assessed by the area under the ROC curve for the summed frequency score. This suggests that using the Rome II definition of dyspepsia instead of the 1988 Working Party definition has little influence on the concurrent validity of the SF-LDQ. Both GERD and dyspepsia have recently been re-defined by the Rome III panel.36, 37 These changes are designed to aid further research in selected subgroups of patients and do not alter the nature of symptoms sought as outcome measures for use in uninvestigated patients, where both reflux symptoms and epigastric pain commonly coexist.

The correlation between the test–retest SF-LDQ scores 2 days apart was 0.93, showing a high degree of reliability. Whilst only 40% of patients returned the second questionnaire, this low response rate was not unexpected for a primary care sample where most participants do not have dyspepsia. The LDQ had a weaker correlation between the two questionnaire scores (0.83) when test–retest reliability was assessed,10 but the response rate for the second questionnaire was higher (96% in a secondary care population). Validation of the SF-LDQ as a postal questionnaire was not carried out in this study. However, the reliability, validity and responsiveness should not be affected by postal completion, as it is a self-completed instrument. Interpretability and acceptability of the SF-LDQ were demonstrated, suggesting that the questionnaire should have a good response rate. The response rate was only 40% in the test–retest sample, but it was 78% in the responsiveness to change sample (secondary care), where dyspepsia was more salient to the respondents. The SF-LDQ's responsiveness to change was highly statistically significant in 37 patients receiving a treatment of known effectiveness. The standardized response mean values suggested this response to change was large. The LDQ was assessed in a similar way and was found to be equally responsive to change, although the standardized response mean was not calculated.10 Other studies have used two groups receiving treatment and placebo, in order to compare the responsiveness of the two groups.38, 39 However, it is not ethical to use placebos except in the context of a randomized-controlled trial, so this was not possible in this study. There was no alternative method of confirming that a response to change had occurred in this study, such as a blinded clinician assessment after treatment or a question on self-reported global improvement, as the treatments used have proven efficacy.40–42

Three percent of respondents commented that the text size was too small and a larger version of the questionnaire should be made available for such patients in clinical trials. Non-English speaking patients were excluded from this study, but should be included in clinical dyspepsia trials to increase generalizability. Translation of the SF-LDQ into other languages would alter its characteristics, necessitating further validation.17, 31

The SF-LDQ is a self-completed outcome measure that assesses both the frequency and severity of dyspepsia symptoms for which acceptability, interpretability, reliability, validity and responsiveness to change have been demonstrated. It is a precise measure using the summed total score of frequency and severity responses and has good feasibility due to its brevity. The SF-LDQ meets all the criteria for an outcome measure for dyspepsia in cost-effectiveness trials, and is particularly well suited to primary care trials involving uninvestigated patients.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

This work was undertaken by Dr Adam Fraser as part of a Masters in Primary Care degree at the University of Birmingham. John C. Duffy provided statistical advice at the Department of Primary Care and General Practice, University of Birmingham. He carried out the sensitivity analyses and logistic regression analyses. Val Redman and Beth Hinks are Research Associates at the Department of Primary Care and General Practice, University of Birmingham. They assisted with patient recruitment and data entry.

Author contributions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Adam Fraser: Lead contributor to study design and planning, conducting the study, data analysis and writing the manuscript; Brendan C. Delaney: guarantor of the submission and corresponding author. Contributed to study design and planning, and writing the manuscript; Alexander C. Ford: responsible for conducting the secondary care arm of the study at Leeds General Infirmary; Michelle Qume: contributed to conducting the study, data entry and analysis and writing the manuscript; Paul Moayyedi: contributed significantly to study design and planning, especially questionnaire development. All authors have checked and approved the final draft submitted.

Statement of interests

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References

Authors’ declaration of personal interests: All authors were employed by the University of Birmingham at the time of this study.

Declaration of funding interests: The study was funded in full by the Medical Research Council as part of the CUBE trial (ISRCTN 87644265). The general practices involved were reimbursed by the Midlands Research Practices Consortium (MidReC) for each patient enrolled. Gastroenterologists recruited patients in secondary care without remuneration.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Author contributions
  9. Statement of interests
  10. References
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