Quality of life in functional dyspepsia: responsiveness of the Nepean Dyspepsia Index and development of a new 10-item short form
Professor N. J.Talley, Department of Medicine, University of Sydney, Nepean Hospital, Penrith, 2751, N.S.W., Australia. E-mail: email@example.com
The Nepean Dyspepsia Index is a reliable and valid measure of quality of life in functional dyspepsia, but responsiveness has been little studied. The Nepean Dyspepsia Index originally contained 42 items designed to measure impairment of a subject’s ability to engage in relevant aspects of their life because of dyspepsia, and their enjoyment of these aspects; in addition, the individual importance of areas was assessed. It was subsequently shortened to 25 items, yielding five sub-scales.
To test the Nepean Dyspepsia Index’s responsiveness and develop a responsive, very short form.
A randomized, double-blind controlled trial was performed in 589 patients with documented functional dyspepsia. Symptoms and quality of life were measured at baseline, 2 and 4 weeks. Responsiveness of the Nepean Dyspepsia Index quality-of-life section was evaluated by correlation with symptom scores and calculation of standardized changes in scores. Two items from each sub-scale which best represented the area of life (by factor loadings) were selected to create the 10-item short form (SF; short form-Nepean Dyspepsia Index). Internal consistency was assessed by Cronbach’s alpha and responsiveness was assessed as above.
The Nepean Dyspepsia Index quality-of-life scales demonstrated excellent responsiveness to change in both the active and placebo arms (standardized response means all > 1.0). The Nepean Dyspepsia Index accounted for only 8% of the variance in percentage change in symptoms (by visual analogue scales), indicating that it was evaluating areas of life not covered by symptoms. The 10-item short form had adequate internal consistency (all scales ≥ 0.70) and all strongly (and significantly) correlated with the long form sub-scales; it was also highly responsive.
The Nepean Dyspepsia Index is a responsive disease-specific quality-of-life measure; the 10-item short form can be applied in clinical trials of functional dyspepsia.
Health-related quality of life refers to how disease impacts on those areas of life that make it worth living, including physical and emotional functioning.1 Substantially reduced quality of life has recently been documented in patients with functional dyspepsia.2–7 However, earlier studies primarily applied non-specific quality of life instruments, such as the short form-36 (SF-36) or the Psychological General Well-Being Index, which contain multiple items, many of which may be irrelevant to dyspepsia.1, 8–10
Only recently has serious attention been given to developing accurate symptom and quality-of-life outcome measures in functional dyspepsia.8, 9 In clinical trials, quality of life is often considered as a secondary outcome to symptom relief, but there is increasing interest in considering quality-of-life improvement as a primary objective of therapy in conditions such as functional dyspepsia, which cause no mortality.8, 9 However, there would be no value in assessing quality of life if the symptom measures cover essentially the same patient concerns. In functional dyspepsia, this has been a little-studied area.
A self-report disease specific questionnaire for functional dyspepsia, the Nepean Dyspepsia Index, has been developed to measure both symptom status and quality of life.3, 4 In previous studies, we have demonstrated that the 42-item Nepean Dyspepsia Index quality-of-life questionnaire appeared to be reliable and accurate. It could also discriminate dyspepsia from health in uninvestigated patients with dyspepsia recruited from family practice in Australia and in a random population sample from New Zealand.3 The Nepean Dyspepsia Index had four sub-scales identified originally. A subsequent study of 101 US patients with functional dyspepsia showed that the Nepean Dyspepsia Index could be shortened to 25 quality-of-life items with five sub-scales; the revised instrument remained reliable and valid.4 Its ability to measure change (i.e. responsiveness) was assessed but not in the setting of a large randomized controlled trial; the initial responsiveness data were encouraging but not definitive.4
The aim of this study was to develop an even briefer, easy to score self-report measure that reliably and validly measures symptoms and quality of life in functional dyspepsia, and is sensitive to change in clinical status. We also wished to determine whether symptom assessment alone is adequate in clinical trials to capture the impact of functional dyspepsia. We therefore applied the Nepean Dyspepsia Index in a large multicentre trial in Europe and the United States, which provided an opportunity to prospectively test the instrument in functional dyspepsia.
The conceptual basis of the Nepean Dyspepsia Index was first developed in Sydney in consultation with an international research team.3 Initial items were chosen through consultation with patients, and local gastroenterology and psychology staff. These items were then pre-tested amongst patient populations in four countries (Australia, Germany, Italy and the Netherlands) using focus groups and face-to-face interviews to identify a comprehensive set of relevant disease specific items. To ensure all the relevant issues were measured, the Nepean Dyspepsia Index was reviewed by an international panel of experts in gastroenterology and items were carefully selected. A revised version of the Nepean Dyspepsia Index was then created; this incorporated 42 items which assessed quality of life across 17 key aspects of life.3 A completely separate symptom checklist was included that measured the frequency, intensity and bothersomeness of 15 upper gastrointestinal symptoms over the prior 2 weeks. A 2-week period was chosen in order to minimize recall bias yet cover an adequate period for measurement of usual activities and symptom status.8 The inclusion of a symptom checklist provides the instrument with an internal standard against which to compare the Nepean Dyspepsia Index’s quality of life measurement.
An important aspect of the philosophy underlying the Nepean Dyspepsia Index was that it be sensitive to the differing priorities and individual value systems of dyspepsia patients. This was achieved by allowing individuals to apply differing weights (equivalent to priorities) to common groups of items or themes (based on key aspects of life) in the Nepean Dyspepsia Index, such as the impact of dyspepsia on daily living or sleep. These weights were incorporated into the Nepean Dyspepsia Index scoring system that was developed. In the initial validation study, weighting did not influence the discriminant value of the questionnaire but it did appear to be of value in a subsequent report.3, 4 The questionnaire has undergone validated translation from Australian English to French, Dutch, Italian, German, Spanish and American English.
The major results of this trial have been reported elsewhere.11 The trial was approved by local Institutional Review Boards, and all patients gave informed consent. Patients at least 18 years of age with a minimum 3-month history of chronic upper abdominal discomfort (i.e. postprandial fullness, bloating, epigastric discomfort, early satiety, belching after meals, postprandial nausea, vomiting or epigastric pain) were eligible for enrolment. A total of 738 patients were screened by 19 investigators in Europe and 21 investigators in the US between May 1997 and June 1998. Patients were required to have a normal upper endoscopy (i.e. no ulcers or erosions in the oesophagus and gastroduodenum) in the 3 months before randomization. Furthermore, during the baseline evaluation over 14 days, patients had to have experienced postprandial upper abdominal discomfort on 3 or more days per week and have sufficiently severe symptoms, defined as a total upper abdominal discomfort severity score of > 149 mm and a postprandial fullness severity score of > 29 mm on visual analogue scales, as described below. Patients were only enrolled if there were no serious co-morbid illnesses and screening laboratory values were normal.
Excluded were patients with gastro-oesophageal reflux disease, based on a normal endoscopy (only erythema was permitted) and those with an absence of predominant daytime or night-time heartburn (predominant being defined as a severity score for heartburn equal to or greater than the postprandial fullness severity score, as described below). Predominant ulcer-like dyspepsia (pain) and symptoms suggestive of irritable bowel syndrome also resulted in exclusion. Patients with organic causes of gastroparesis (e.g. diabetes mellitus) and other serious disease (including alcoholism and drug dependence, any bowel surgery or malignancy) were excluded. Occasional non-steroidal anti-inflammatory drug use (< 11 days per month) or aspirin (< 101 mg daily) was permitted, but prokinetic, antisecretory or antacid therapy within 3 days of screening and throughout the treatment period was not.
A total of 612 patients were randomized but three were lost to follow-up after drug was dispensed and were excluded. Patients treated (n=609) were randomly assigned to the motilin agonist ABT 229 1.25 mg (n=118), 2.5 mg (n=121), 5 mg (n= 126), 10 mg (n=123) or placebo (n=121) twice daily for 4 weeks. Nepean Dyspepsia Index data were available for 589 of these patients. A total of 47 patients prematurely discontinued because of adverse events (n=18), non-compliance (n=7), treatment failure (n=14), or other reasons (n=5), or were lost to follow-up (n=3); the distribution was similar in each arm and 562 patients completed the trial.
Patient Symptom Questionnaire: visual analogue scales.
At baseline, 2 and 4 weeks, all patients completed an independent self-report measure of the severity, frequency, duration and impact of symptoms over the prior 2 weeks. The target symptoms were postprandial fullness, early satiety, bloating, epigastric discomfort (an ache or discomfort after eating, poorly localized), epigastric pain (a sharp, easy to pinpoint pain after eating), postprandial nausea, belching after meals and vomiting. Severity was scored for each symptom on a 100-mm visual analogue scale. The primary outcome was defined a priori as the sum of severities of the eight symptoms, to create the total upper abdominal discomfort severity score (minimum 0, maximum 800 mm). Defining each symptom in lay-person terms standardized the questionnaire, and cultural differences were minimized by comprehensive forward and backward linguistic translations of all measures. A visual analogue scale is sensitive to change and is well-accepted as a tool for evaluating symptoms.8
Nepean Dyspepsia Index.
Quality of life was filled in by each patient at baseline and at 4 weeks. The Nepean Dyspepsia Index quality-of-life scale consisted of the original questions, measuring health-related quality of life structured around 17 key areas of life.
For most of the quality-of-life areas, the impact of the illness was considered to occur in two dimensions: interference with a subject’s ability to perform or engage in the area (e.g. a reduced ability to spend time with friends because of dyspepsia); and interference with their enjoyment of that area of life (e.g. impaired enjoyment of time spent with friends because of dyspepsia). These were measured by 5-point Likert scales from 0 (not at all or not applicable), 1 (a little), 2 (moderately), 3 (quite a lot) to 4 (extremely).
Five sub-scales, namely interference with daily activities (nine question items), knowledge/control (six items), tension (three items), work/study (four items) and eating/drinking (three items) were derived, as previously described.4 These five sub-scales comprising the full Nepean Dyspepsia Index were subsequently evaluated.
The Nepean Dyspepsia Index symptom scale measured the frequency, severity and bothersomeness of 15 upper gastrointestinal symptoms, applying a scale of 0 (not at all) to 4 (daily) for frequency, 0 (not at all) to 5 (very severe) for intensity, and 0 (not at all) to 4 (extremely bothersome) for bothersomeness. Scores were added over the three groups of symptoms.
Three patient-reported assessments of dyspepsia were evaluated: (i) eight symptoms according to the independent visual analogue scales in the Patient Symptom Questionnaire; (ii) 15 symptoms according to the Nepean Dyspepsia Index symptom checklist; and (iii) health-related quality of life according to the five Nepean Dyspepsia Index scales.
Internal consistency (reliability).
In combining responses to several questions, it is assumed that they are all measuring some common underlying concept (construct). This can be assessed by measuring the internal consistency of the items. A common and well-accepted index of internal consistency is Cronbach’s alpha.12 Internal consistency was assessed by Cronbach’s alpha by first using all quality-of-life items in the full Nepean Dyspepsia Index, then using the 10-item short form as described below.
Responsiveness (ability to measure change).
Responsiveness of the Nepean Dyspepsia Index symptom and quality-of-life scales to changes in the patient’s underlying status was first assessed by correlation (Spearman rank) with the Patient Symptom Questionnaire and secondly by descriptive comparison of percentage change in each of the three patient-reported assessments. Correlations between quality-of-life and symptom scores were undertaken both at fixed times (baseline and end of study) and in terms of change from baseline to end of study. The latter correlations directly assess responsiveness, while the former provide insight into the equivalence of these scales.
The standardized change in score (standardized response mean) was calculated by dividing the mean change by the standard deviation of the change. Values > 1.0 indicate excellent responsiveness.
Item reduction to create a short form Nepean Dyspepsia Index.
A simpler form of the quality-of-life index was calculated to assess the viability of a much shorter scale. The item reduction strategy was based on the knowledge that multiple items measuring a single construct are likely to be strongly correlated and hence involve some redundancy. It was hypothesized that the two items with the highest factor loadings on each of the five sub-scales would provide an adequate representation of the relevant areas, yielding a 10-item quality-of-life scale. The pairs of items were combined in an unweighted sum (Appendix 1).
The extent to which the short form Nepean Dyspepsia Index quality-of-life scales provided representation of the full-item scales was assessed in several ways. Each simplified sub-scale score was correlated with its original, complete counterpart. In addition, canonical correlation and multivariate regression were used to assess how the simplified scales provided representation of the complete scales. Responsiveness was estimated as described above.
All P-values calculated were two-tailed; the alpha level of significance was set at P < 0.05.
Trial outcome: Patient Symptom Questionnaire
Patients (n=589) were on average middle aged (mean 46 years, s.d. 14), with a preponderance of females (69%, n=409) and mostly of Caucasian origin (91%, n=537). A total of 474 patients received a dose of the motilin agonist and 115 received placebo.
The upper abdominal discomfort severity score significantly decreased in all treatment arms from baseline on the intention-to-treat analysis. However, there were no significant differences between each of the active treatment arms and placebo for mean change from baseline to week 2 or week 4, as previously reported.11 Therefore, all the active treatment arms were combined for the subsequent analyses.
Placebo and active drug patients were very similar in terms of baseline symptom levels according to both the Nepean Dyspepsia Index symptom checklist and the visual analogue scales from the Patient Symptom Questionnaire, and in terms of quality of life as assessed by the full Nepean Dyspepsia Index (Table 1). The same was apparent at the end of the study (Table 1). Percentage changes in symptom scores were very similar in the active drug and placebo groups, and were also similar between the Patient Symptom Questionnaire and the Nepean Dyspepsia Index symptom scales (Table 2).
Mean symptom scores from the Patient Symptom Questionnaire and the full Nepean Dyspepsia Index (NDI) at baseline and 4 weeks
Change in symptoms and quality of life (full and short form Nepean Dyspepsia Index)
Strong correlations were observed between the change in Nepean Dyspepsia Index symptoms and the Patient Symptom Questionnaire visual analogue scales, both when assessed as absolute change (r=0.54, P < 0.0001) and when assessed as percentage change (r=0.66, P < 0.0001).
Quality of life responsiveness
Considering the full-item Nepean Dyspepsia Index, the largest percentage changes in quality of life were observed in the knowledge/control, interference with daily activities and tension sub-scales. Larger changes were present in the placebo group than in the active drug group for some sub-scales, consistent with the changes in symptom scores (Table 2). Percentage changes in the eating/drinking and work/study sub-scales were relatively modest (Table 2). A similar pattern was observed for the 10-item short form Nepean Dyspepsia Index (Table 2).
Statistically significant correlations were found between changes in the Patient Symptom Questionnaire scale and changes in full Nepean Dyspepsia Index quality-of-life sub-scales on both an absolute and percentage basis (Table 3). The percentage change yielded somewhat larger correlations than absolute change. This is logical because percentage change corrects more completely for differences in ‘potential’ to change. Considered jointly, through multiple regression, Nepean Dyspepsia Index quality-of-life items accounted for only 8% of the variance in percentage change in Patient Symptom Questionnaire scores and 14% of the absolute change.
Spearman rank correlations of quality-of-life changes in the Nepean Dyspepsia Index with the Patient Symptom Questionnaire
The Nepean Dyspepsia Index quality-of-life sub-scales all demonstrated excellent responsiveness, because all standardized effect sizes exceeded 1.0 (Table 4). Similarly, the Nepean Dyspepsia Index symptom scales showed good responsiveness with a standardized effect score > 1.0 in the active group and just under 1.0 (0.98) in the placebo group. The Patient Symptom Questionnaire scale showed moderate responsiveness with a standardized effect size of around 0.8 in both study groups (Table 4).
Responsiveness of the symptom and quality-of-life scales in the active and placebo arms
In terms of clinical trial planning, given the sample size achieved in this trial, and had the difference between the active and placebo arms been as large as 15% (assuming a s.d. of change of 40% as an average across scores), the statistical power would have been 0.93. Conversely, to achieve a statistical power of 0.80 under the same conditions, 112 subjects would have been required per study group.
Performance of the short form
Adequate internal consistency (Cronbach’s alpha) was found for all five two-item short form quality-of-life sub-scales between baseline and the end of the study (tension 0.71, interference with daily activities 0.70, eating/drinking 0.71, knowledge/control 0.76, and work/study 0.74). The full item quality-of-life sub-scale scores were all very strongly correlated with their two-item equivalents (Table 5, all P < 0.0001), whether considering scores at baseline, absolute change or percentage change.
Correlations between full-item and two-item scores quality-of-life scales in the Nepean Dyspepsia Index
The percentage reductions in the five short form Nepean Dyspepsia Index quality-of-life sub-scales were of similar magnitude to those observed for the full-item scales. The exception was the knowledge/control sub-scale, which exhibited the largest change on a full-item basis but the smallest on the reduced item basis.
Statistically significant correlations were found between changes in the Patient Symptom Questionnaire scales and changes in the short form Nepean Dyspepsia Index quality-of-life sub-scales, on both an absolute and percentage basis (Table 3). These were equal to or greater than those observed among the full-item scales (Table 3). Considered jointly, through multiple regression, Nepean Dyspepsia Index short form quality-of-life items accounted for 19% of the variance in percentage change in the Patient Symptom Questionnaire visual analogue symptom score and 22% of the absolute change. This was actually larger than found for the full Nepean Dyspepsia Index item data.
Strong correlations were found at baseline between the full-item sub-scales and both the 10 individual items which make up the reduced scale (first two canonical correlations 0.93, 0.78) and the five reduced item sub-scales (first two canonical correlations 0.93, 0.77). Similar canonical correlations were found after treatment.
While dyspepsia is a recognized major health problem in the community, probably costing billions annually in the United States, treatment remains unsatisfactory.13 When testing new therapies, validated measures of outcome are needed which are responsive to change, yet these have been largely unavailable.3 The Rome II Working Teams have recommended the use of validated quality-of-life instruments in clinical trials of patients with functional gastrointestinal disorders, especially when such instruments have been shown to be able to detect change.14 Generic instruments are unlikely to be as useful as a disease-specific measure for quantifying changes in impaired quality of life in functional dyspepsia with therapy.15 The lack of availability of a disease specific quality-of-life measure for functional dyspepsia has, in the past, limited the options for researchers.16
The Nepean Dyspepsia Index questionnaire described in this study is actually composed of two distinct, separately scored and interpreted instruments: a symptom checklist and a disease specific quality-of-life measure. The former is made up of a list of common upper gastrointestinal symptoms which respondents rate in terms of three dimensions, whilst the full Nepean Dyspepsia Index quality-of-life section is composed of 25 items which include disease impact items and an importance rating.4 A measurement instrument is valid if the information recorded corresponds to the true state of affairs.17 For this to be the case, the instrument must be reliable; hence repeated measurements should fall closely to each other assuming the situation is stable.17 We have previously shown that the full version of the Nepean Dyspepsia Index was reliable on two distinct occasions by test–retest and had high internal consistency. In the present study, we confirmed the internal consistency of the long form and found that the short 10-item version also had high internal consistency. Hence, we conclude that the Nepean Dyspepsia Index has excellent reliability across various study populations.
However, reliability alone does not necessarily establish validity; an instrument may reliably measure concepts that are systematically missing the mark.17 Because no gold standard exists to establish the validity of a quality-of-life measure, determining an instrument’s validity requires a number of steps. We have previously established that the full Nepean Dyspepsia Index quality-of-life items measure relevant areas of life in patients with functional dyspepsia (i.e. the instrument has face and content validity) and the long form Nepean Dyspepsia Index discriminates patients with uninvestigated dyspepsia from healthy subjects (discriminant validity).3, 4 Furthermore, the instrument measures concepts that are linked to but are not covered by the symptom evaluation.4 Importantly, in the present study we confirmed that symptom items did not adequately explain the quality-of-life domains captured by the Nepean Dyspepsia Index. Similarly, we have previously reported that the SF-36 (a well-established generic quality-of-life measure) correlated with the Nepean Dyspepsia Index, and anxiety and depression also correlated with the Nepean Dyspepsia Index, but none of these measures alone or combined could replace the Nepean Dyspepsia Index (convergent validity).4 It therefore appears that the Nepean Dyspepsia Index can be usefully and confidently applied in studies of functional dyspepsia.
A potential omission with all previous quality-of-life instruments in gastroenterology has been the lack of weighting of items relating to the relative importance to each individual.1 In individuals, certain activities that really matter to that person are likely to be more affected by an illness. Theoretically, weighting the importance of domains could improve the performance of an instrument. In our original report, rating of importance in the Nepean Dyspepsia Index was not of additional discriminatory value.3 While we have subsequently shown that weighting may be of some relevance, it appears not to be essential, based on the present results.4 We found that the originally constructed quality-of-life instrument could be further simplified into five two-item sub-scales, with a total of just 10 items. Applying individual weights from the original groups of items was not required, based on the psychometric testing performed.
In previous work, initial data on responsiveness were also gathered but only a 2-week period was measured.4 While the data suggested that the instrument was at least modestly responsive, as there was no specific intervention tested in this study, large changes were not expected. For this reason, we set out to test the Nepean Dyspepsia Index in a large clinical trial, to determine its level of responsiveness and set the scene for future work. We found that symptoms and quality of life significantly changed from baseline in parallel in the present trial. Concordant with the independent symptom measures, large changes were observed in the placebo and active therapy groups. We assessed the standardized response mean to document sensitivity to change; similar, high responsiveness scores for both the full and short versions of the Nepean Dyspepsia Index were observed. Hence, we now have available a very brief, valid disease-specific quality-of-life measure that can be applied in clinical trials of functional dyspepsia. A strength of the study is that we did include a wide range of patients from multiple countries in this trial, and hence the results should be broadly generalizable.
There are few other disease-specific quality-of-life measures available for dyspepsia. Rabeneck and colleagues reported the development of the SODA (severity of dyspepsia assessment).18 However, this is a complex instrument to score and does not measure quality of life but rather symptoms and satisfaction. Furthermore, its responsiveness is not established and the generalizability outside of males in a Veterans Administration (VA) hospital setting needs to be determined. An international research group has independently developed the quality of life in reflux and dyspepsia (QOLRAD) questionnaire.19 This instrument is psychometrically sound; it contains 25 items measuring emotions, vitality, sleep, diet and physical/social functioning, and is very responsive to change in GERD.20 On the other hand, a distinction between dyspepsia and reflux was not a goal of instrument development and its responsiveness in functional dyspepsia is uncertain. The Gastrointestinal Symptom Rating Scale (GSRS) is a valuable symptom measure but it is not specific for dyspepsia and does not assess quality of life.21 McColl and co-workers have developed the Glasgow Dyspepsia Severity Score.22 Rather than a comprehensive disease-specific quality-of-life measure, the Glasgow scale is an investigator-based global measure of dyspepsia (which is not defined in the instrument); specific symptom items are not assessed. It also asks about the global effect on routine activities, time off work, consultations, tests and medications, and importantly is relatively brief and responsive. However, a disadvantage of the Glasgow scale is its reliance on the investigator (and his or her definition of dyspepsia, which is likely to not be standardized). A study from Ireland has also reported the validation of a new dyspepsia measure, but it only measures four symptoms and the validity remains to be adequately established.23 A study from the US reported excellent psychometrics for the Digestive Health Status Instrument (DHSI), but this is not a quality-of-life measure.24
In conclusion, we have developed a valid multidimensional disease-specific quality-of-life measure that was highly responsive to change in a clinical trial. The available results suggest that the short form Nepean Dyspepsia Index will be useful in future clinical trials of dyspepsia and functional dyspepsia.
This study was supported by an unrestricted research grant from Abbott Laboratories, USA.
A copy of the full Nepean Dyspepsia Index is available from Dr N. J. Talley.
APPENDIX 1: SHORT FORM NEPEAN DYSPEPSIA INDEX©
1. Has your general emotional well-being been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
2. Have you been irritable, tense or frustrated in the last 2 weeks because of your stomach problems?
1 not at all
2 a little
4 quite a lot
Interference with daily activities
3. Has your ability to engage in things you usually do for fun (recreations, going out, hobbies, sports, etc.) been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
4. Has your enjoyment of things you usually do for fun (recreations, going out, hobbies, sports, etc.) been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
1 not applicable (I have not been able to do any of these things in the past 2 weeks)
5. Has your ability to eat or drink (including when, what, and how much) been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
6. Has your enjoyment of eating and/or drinking been disturbed by your stomach problems in the last 2 weeks? (Please also include your appetite, and how you feel after food or drink).
1 not at all
2 a little
4 quite a lot
7. Have you wondered whether you will always have these stomach problems, in the last 2 weeks?
1 almost never
3 fairly often
4 very often
8. Have you thought that your stomach problems might be due to a very serious illness (e.g. cancer or a heart problem), in the last 2 weeks?
1 almost never
3 fairly often
4 very often
9. Has your ability to work or study been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
1 not applicable (I do not work or study).
10. Has your enjoyment of work or study been disturbed by your stomach problems in the last 2 weeks?
1 not at all
2 a little
4 quite a lot
1 not applicable (I have not worked or studied in the last 2 weeks).
Scoring: Add up the items for each of the five sub-scale scores (range of each sub-scale 2–10).