The difference in event rates between two groups (one subtracted from the other) in a comparative study.

Summary of a study, which may be published alone or as an introduction to a full scientific paper.

An ancient Chinese technique involving the insertion of fine needles just under the skin in specific locations in order to relieve pain and treat a wide variety of complaints. Historically, acupuncture is one component of an overall program of Chinese medicine that includes theory, practice, diagnosis, physiology, and the use of herbal preparations.

A statistical procedure in which the effects of differences in composition of the populations being compared (or treatment given at the same time) have been minimised by statistical methods.

A flow chart of the clinical decision pathway described in the guideline, where decision points are represented with boxes, linked with arrows.

The process used to prevent advance knowledge of group assignment in a RCT. The allocation process should be impervious to any influence by the individual making the allocation, by being administered by someone who is not responsible for recruiting participants.

The degree to which the results of an observation, study or review are likely to hold true in a particular clinical practice setting.

Subsection of individuals within a study who receive one particular intervention, for example placebo arm.

Statistical relationship between two or more events, characteristics or other variables. The relationship may or may not be causal.

The initial set of measurements at the beginning of a study (after run-in period where applicable), with which subsequent results are compared.

A generic term to describe forms of psychological therapy based on the concept that the way we think about things affects how we feel and act. Behavioural therapy focuses on thinking and behaviour and it aims to help people in the ways they act (behaviour).

Systematic (as opposed to random) deviation of the results of a study from the ‘true’ results that is caused by the way the study is designed or conducted.

A technique in which an individual learns to consciously control involuntary responses such as heart rate, brain waves, and muscle contractions. Information about a normally unconscious physiologic process is relayed back to the patient as a visual, auditory, or tactile signal. These responses are electronically monitored and noted through beeps, graphs, or on a computer screen, which are seen and heard by the participant.

Keeping the study participants, caregivers, researchers and outcome assessors unaware about the interventions to which the participants have been allocated in a study

Fullness or swelling in the abdomen that often occurs after meals

The rumbling noise produced by the movement of gas through the intestines. The plural of this word is borborygmi.

A validated, illustrated tool used to define stool type and consistency developed by Dr K W Heaton, Reader in Medicine at the University of Bristol. Copyright Norgine Ltd 2000.

Someone other than a health professional who is involved in caring for a person with a medical condition.

A study in which the amount of exposure to a potentially causative factor in a group of patients (cases) who have a particular condition is compared with the exposure in a similar group of people who do not have the clinical condition (the latter is called the control group).

The extent to which an intervention is active when studied under controlled research conditions.

The extent to which an intervention produces an overall health benefit in routine clinical practice.

The effect that a guideline recommendation is likely to have on the treatment or treatment outcomes, of the target population.

In guideline development, this term refers to the questions about treatment and care that are formulated to guide the development of evidence-based recommendations.

A healthcare professional providing healthcare, for example doctor, nurse or physiotherapist.

A regularly updated electronic collection of evidence-based medicine databases, including the Cochrane Database of Systematic Reviews.

A systematic review of the evidence from randomised controlled trials relating to a particular health problem or healthcare intervention, produced by the Cochrane Collaboration. Available electronically as part of the Cochrane Library.

Coeliac disease (also called celiac disease, non-tropical sprue, c(o)eliac sprue and gluten intolerance) is an autoimmune disorder characterised by damage to all or part of the villi lining the small intestine. This damage is caused by exposure to gluten and related proteins found in wheat, rye, malt and barley, and to a lesser degree in oats.

A relatively short-term form of psychotherapy based on the concept that the way we think about things affects how we feel emotionally. Cognitive therapy focuses on present thinking, behaviour, and communication rather than on past experiences and is oriented toward problem solving. It aims to help people in the ways they think (cognition) and in the ways they act (behaviour).

A retrospective or prospective follow-up study. Groups of individuals to be followed up are defined on the basis of presence or absence of exposure to a suspected risk factor or intervention. A cohort study can be comparative, in which case two or more groups are selected on the basis of differences in their exposure to the agent of interest.

Coexistence of more than one disease or an additional disease (other than that being studied or treated) in an individual.

Similarity of the groups in characteristics likely to affect the study results (such as health status or age).

The extent to which a person adheres to the health advice agreed with healthcare professionals. May also be referred to as ‘adherence’.

An approach first used in the prescribing and taking of medicines but can be applied to many treatments in healthcare. It is an agreement reached after negotiation between a patient and a health care professional that respects the beliefs and wishes of the patient in determining whether, when and how medicines/treatments are to be taken. Although reciprocal, this is an alliance in which the health care professionals recognise the primacy of the patient’s decisions about taking the recommended medications.

The range of numerical values within which we can be confident that the population value being estimated is found. Confidence intervals indicate the strength of evidence; where confidence intervals are wide they indicate less precise estimates of effects.

In a study, confounding occurs when the effect of an intervention on an outcome is distorted as a result of an association between the population or intervention or outcome and another factor (the ‘confounding variable’) that can influence the outcome independently of the intervention under study.

Techniques that aim to reach an agreement on a particular issue. Formal consensus methods include Delphi and nominal group techniques, and consensus development conferences. In the development of clinical guidelines, consensus methods may be used where there is a lack of strong research evidence on a particular topic. Expert consensus methods will aim to reach agreement between experts in a particular field.

A condition in which bowel movements are infrequent, hard and dry, and elimination of faeces is difficult and infrequent.

The process that allows stakeholders and individuals to comment on initial versions of NICE guidance and other documents so their views can be taken into account when the final version is being produced.

A type of economic evaluation, which estimates the net benefit to society of an intervention as the incremental (difference in) benefit of the intervention minus the incremental (difference in) cost, with all benefits and costs measured in monetary units. If benefits exceed costs, the evaluation would be a basis for recommending the intervention.

A type of economic evaluation, whereby both outcomes and costs of alternative interventions are described, without any attempt to combine the results.

The cost per unit of benefit of an intervention. Benefits of different interventions are measured using a single outcome (for example, life-years gained, quality-adjusted life-years gained, deaths avoided, heart attacks avoided, cases detected).

An economic study design in which alternative interventions are compared in terms of cost per unit of effectiveness.

An explicit mathematical framework, which is used to represent clinical decision problems and incorporate evidence from a variety of sources in order to estimate the costs and health outcomes.

An analysis of the total costs incurred by a society due to a specific disease.

The total cost to the person, the NHS or to society.

A type of economic evaluation used to compare the difference in costs between programs that have the same health outcome.

The simplest form of economic study, measuring only the costs of given interventions.

A form of cost-effectiveness analysis in which the units of effectiveness are quality-adjusted life-years (QALYs).

The skilled use of the relationship (between the counsellor and patient) to help the patient develop self-knowledge, self-esteem and the ability to take control of his or her own life. (The British Association of Counselling and Psychotherapy).

A chronic inflammatory disease of the digestive tract and it can involve any part of it - from the mouth to the anus. It typically affects the terminal ileum as well as demarcated areas of large bowel, with other areas of the bowel being relatively unaffected. It is often associated with auto-immune disorders outside the bowel, such as rheumatoid arthritis.

Examination of the relationship between disease and other variables of interest as they exist in a defined population assessed at a particular time.

Tabulated presentation of data collected from individual studies.

A clear specification of the interventions, patient populations and outcome measures and perspective adopted in an evaluation, with an explicit justification, relating these to the decision which the analysis is to inform.

A way of reaching decisions, based on evidence from research. This evidence is translated into probabilities, and then into diagrams or decision trees that direct the clinician through a succession of possible scenarios, actions and outcomes.

A systematic interactive forecasting method based on independent inputs of a panel of selected experts over two or more rounds. Questions are usually formulated as hypotheses and experts are asked to comment. Each round of questioning is followed with the feedback on the preceding round of replies, usually presented anonymously. Thus the experts are encouraged to revise their earlier answers in light of the replies of other members of the group. It is believed that during this process the range of the answers will decrease and the group will converge towards the “correct” answer. After several rounds the process is complete and the median scores determine the final answer.

A deterministic analysis is one in which the best estimate for each parameter has been used to give a single estimate of cost-effectiveness. It is the opposite of a probabilistic sensitivity analysis (See sensitivity analysis).

A condition in which the sufferer has frequent and watery or loose bowel movements (from the ancient Greek word διαρροή = leakage; lit. “to run through”).

Distinguishing between two or more diseases and conditions with similar symptoms by systematically comparing and contrasting their clinical findings, including physical signs, symptoms, as well as the results of laboratory tests and other appropriate diagnostic procedures. See also Red Flags.

Costs and perhaps benefits incurred today have a higher value than costs and benefits occurring in the future. Discounting health benefits reflects individual preference for benefits to be experienced in the present rather than the future. Discounting costs reflects individual preference for costs to be experienced in the future rather than the present.

An intervention is said to be dominated if there is an alternative intervention that is both less costly and more effective.

The prescribed amount of a drug to be taken, including the size and timing of the doses.

A participant who withdraws from a clinical trial before the end.

Comparative analysis of alternative courses of action in terms of both their costs and consequences.

The observed association between interventions and outcomes or a statistic to summarise the strength of the observed association.

See “Clinical effectiveness”

See “Clinical efficacy”

A procedure that uses an endoscope to diagnose or treat a condition. There are many types of endoscopy; examples include colonoscopy, sigmoidoscopy, gastroscopy, enteroscopy, and esophogealgastroduodenoscopy (EGD).

A study which looks at how a disease or clinical condition is distributed across populations, e.g. across geographical areas or over time, or between age groups.

Information on which a decision or guidance is based. Evidence is obtained from a range of sources including randomised controlled trials, observational studies, expert opinion (of clinical professionals and/or patients).

A table summarising the results of a collection of studies which, taken together, represent the evidence supporting a particular recommendation or series of recommendations in a guideline.

Explicit standards used to decide which studies should be excluded from consideration as potential sources of evidence.

Criteria that define who is not eligible to participate in a clinical study.

See ‘Consensus methods’.

IBS symptoms that are not directly associated with the GI tract but are not uncommon features of IBS e.g. low back pain, bladder symptoms, thigh pain, gynaecological symptoms

In data analysis, predicting the value of a parameter outside the range of observed values.

Positive test diagnostic result in a subject who does not possess the attribute for which the test is conducted. The incorrect labelling of a healthy person following screening.

Gas or wind produced in the intestines, mostly as a result of the normal activity of bacteria in the bowel.

Observation over a period of time of an individual, group or population whose relevant characteristics have been assessed in order to observe changes in health status or health-related variables.

In medicine, the term functional bowel disorder refers to a group of disorders which are characterised by chronic abdominal complaints without a structural or biochemical cause that could explain symptoms. Functional bowel disorders include: * Functional dyspepsia* Non-cardiac chest pain (NCCP)* Chronic abdominal pain* Functional constipation* Irritable bowel syndrome (IBS).

The extent to which the results of a study based on measurement in a particular patient population and/or a specific context hold true for another population and/or in a different context. In this instance, this is the degree to which the guideline recommendation is applicable across both geographical and contextual settings. For instance, guidelines that suggest substituting one form of labour for another should acknowledge that these costs might vary across the country.

The general non-proprietary name of a drug or device.

A research study outcome measuring an overall improvement in a group of defined IBS symptoms (e.g. pain, bowel habit, quality of life). Each symptom is given a score and the aggregate of the scores from each symptom forms the global improvement score.

An aggregate score of groups of IBS symptoms used to measure changes in severity and frequency of symptoms before, during and after treatment interventions.

A method, procedure or measurement that is widely accepted as being the best available, to which a new method is compared.

Recommended good practice based on the clinical experience of the Guideline Development Group.

Reports that are unpublished or have limited distribution, and are not included in the common bibliographic retrieval systems.

A term referring to the contractions of the gastrointestinal tract (peristalsis). These contractions cause food to be pushed through the GI tract in a controlled fashion

Adverse effects of an intervention.

Includes nurses, allied health professionals and doctors.

The study of the allocation of scarce resources among alternative healthcare treatments. Health economists are concerned with both increasing the average level of health in the population and improving the distribution of health.

The process by which evidence on the clinical effectiveness and the costs and benefits of using a technology in clinical practice is systematically evaluated.

A combination of an individual’s physical, mental and social well-being; not merely the absence of disease.

Test for lactose intolerance that measures breath samples for too much hydrogen.

A deep state of relaxation is achieved through focused attention. While in this trance-like state, the unconscious mind is highly receptive to new perspectives and ideas. The use of imagery and positive suggestions at this time can help a client imagine and actually experience herself in the future, as she desires to be. This may make the desired changes happen much faster and with less resistance, as a result of the hypnosis experience.

A supposition made as a starting point for further investigation.

Constipation is termed idiopathic when it cannot be explained by any anatomical, physiological, radiological or histological abnormalities. The exact aetiology is not fully understood but it is generally accepted that a combination of factors may contribute to the condition.

Introducing the use of the guidance recommendations in practice.

The number of new cases of illness commencing, or of persons falling ill during a specified time period in a given population.

Explicit criteria used to decide which studies should be considered as potential sources of evidence.

The analysis of additional costs and additional clinical outcomes with different interventions.

The mean cost per patient associated with an intervention minus the mean cost per patient associated with a comparator intervention.

The difference in the mean costs in the population of interest divided by the differences in the mean outcomes in the population of interest.

The value (usually in monetary terms) of an intervention net of its cost compared with a comparator intervention. The INB can be calculated for a given cost-effectiveness (willingness to pay) threshold. If the threshold is £20,000 per QALY gained then the INB is calculated as: (£20,000 × QALYs gained) – Incremental cost

General term for any disease characterized by inflammation of the bowel. Two of the most common Inflammatory Bowel Diseases are ulcerative colitis and Crohn’s disease. Note: Not to be confused with Irritable Bowel Syndrome.

Healthcare action intended to benefit the patient, for example, drug treatment, surgical procedure, psychological therapy.

The defined use of a technology as licensed by the Medicines and Healthcare products Regulatory Agency (MHRA).

An analysis of the results of a clinical study in which the data are analysed for all study participants as if they had remained in the group to which they were randomised, regardless of whether or not they remained in the study until the end, crossed over to another treatment or received an alternative intervention.

The degree to which the results of a study are likely to approximate the ‘truth’ for the participants recruited in a study (that is, are the results free of bias?). It refers to the integrity of the design and is a prerequisite for applicability (external validity) of a study’s findings.

Factors present within the individual.

An authorisation from the MHRA to market a medicinal product.

Average years of life gained per person as a result of the intervention.

A data analysis technique to derive an equation to predict the probability of an event given one or more predictor variables. This model assumes that the natural logarithm of the odds for the event (the logit) is a linear sum of weighted values of the predictor variable. The weights are derived from data using the method of maximum likelihood.

A statistical technique for combining (pooling) the results of a number of studies that address the same question and report on the same outcomes to produce a summary result. The aim is to derive more precise and clear information from a large data pool. It is generally more reliably likely to confirm or refute a hypothesis than the individual trials.

A statistical model for analysis of the relationship between two or more predictor (independent) variables and the outcome (dependent) variable.

Summary of findings given as a written description.

The proportion of individuals with a negative test result who do NOT have the disease.

A methodology for achieving team consensus quickly when the team is ranking several options or alternatives or selecting the best choice among them. The method basically consists of having each team member come up with his or her personal ranking of the options or choices, and collation of everyone’s rankings into the team consensus.

The number of patients that who on average must be treated to prevent a single occurrence of the outcome of interest.

Retrospective or prospective study in which the investigator observes the natural course of events with or without control groups; for example, cohort studies and case–control studies.

A measure of treatment effectiveness. The odds of an event happening in the treatment group, expressed as a proportion of the odds of it happening in the control group. The ‘odds’ is the ratio of non-events to events.

A drug or device used treat a condition or disease for which it is not specifically licensed.

The opportunity cost of investing in a healthcare intervention is the other healthcare programmes that are displaced by its introduction. This may be best measured by the health benefits that could have been achieved had the money been spent on the next best alternative healthcare intervention.

Measure of the possible results that may stem from exposure to a preventive or therapeutic intervention. Outcome measures may be intermediate endpoints or they can be final endpoints.

A research study outcome measuring changes in pain using an aggregate score of pain type, duration, frequency and severity. Scales used vary.

The probability that an observed difference could have occurred by chance, assuming that there is in fact no underlying difference between the means of the observations. If the probability is less than 1 in 20, the p value is less than 0.05; a result with a p value of less than 0.05 is conventionally considered to be ‘statistically significant’.

A process where research is scrutinised by experts that have not been involved in the design or execution of the studies.

Synchronized or coordinated contraction of the muscles that propel food content through the gastrointestinal (GI) tract to facilitate normal digestion and the absorption of nutrients. Peristalsis is dependent upon the coordination between the muscles, nerves, and hormones in the digestive tract.

An inactive and physically identical medication or procedure used as a comparator in controlled clinical trials.

The proportion of individuals with a positive test result who actually have the disease.

The proportion of persons with a particular disease within a given population at a given time.

A probable course or outcome of a disease. Prognostic factors are patient or disease characteristics that influence the course. Good prognosis is associated with low rate of undesirable outcomes; poor prognosis is associated with a high rate of undesirable outcomes.

The brand name given by the manufacturer to a drug or device it produces.

A set of techniques intended to cure or improve psychological and behavioural problems in humans. The commonest form of psychotherapy is direct personal contact between therapist and patient, mainly in the form of talking.

The treatment of any condition by psychological means. This may utilise insight, persuasion, suggestion, reassurance, and instruction so that patients may see themselves and their problems more realistically and have the desire to cope effectively with them. There are many different psychological interventions, these include psychotherapy, biofeedback, cognitive behavioural therapy, family therapy, hypnotherapy, interpersonal therapy and psychodynamic therapy.

Research concerned with subjective outcomes relating to social, emotional and experiential phenomena in health and social care.

See “Health-related quality of life”

An index of survival that is adjusted to account for the patient’s quality of life during this time. QALYs have the advantage of incorporating changes in both quantity (longevity/mortality) and quality (morbidity, psychological, functional, social and other factors) of life. Used to measure benefits in cost-utility analysis. The QALYs gained are the mean QALYs associated with one treatment minus the mean QALYs associated with an alternative treatment.

An abridged version of NICE guidance, which presents the key priorities for implementation and summarises the recommendations for the core clinical audience.

Allocation of participants in a research study to two or more alternative groups using a chance procedure, such as computer-generated random numbers. This approach is used in an attempt to ensure there is an even distribution of participants with different characteristics between groups and thus reduce sources of bias.

A comparative study in which participants are randomly allocated to intervention and control groups and followed up to examine differences in outcomes between the groups. The random allocation eliminates bias in the assignment of treatment to patients and establishes the basis for the statistical analysis.

A symptom and/or sign that resolves then returns at least once.

A warning term used to indicate further investigation of specific symptoms is warranted to identify potential differential diagnosis.

An agreed standard, for example for a test or treatment, against which other interventions can be compared.

people with IBS who do not respond to first line therapies after 12 months and who develop a continuing symptom profile.

The number of times more likely or less likely an event is to happen in one group compared with another (calculated as the risk of the event in group A/the risk of the event in group B).

The degree of agreement exhibited when a measurement is repeated under identical conditions. Reliability refers to the degree to which the results obtained by a measurement procedure can be replicated.

The brief given by the Department of Health and Welsh Assembly Government at the beginning of the guideline development process. This defines core areas of care that the guideline needs to address.

The likely impact in terms of finance, workforce or other NHS resources.

A study in which a defined group of persons with an exposure that occurred in the past and an appropriate comparison group who were not exposed are identified at a time later than when they were exposed and followed from the time of exposure to the present, and in which the incidence of disease (or mortality) for the exposed and unexposed are assessed.

An article that summarises the evidence contained in a number of different individual studies and draws conclusions about their findings. It may or may not be systematically researched and developed.

Benefits resulting from a treatment in addition to the primary, intended outcome.

A systematic bias in selecting participants for study groups, so that the groups have differences in prognosis and/or therapeutic sensitivities at baseline. Randomisation (with concealed allocation) of patients protects against this bias.

The proportion of individuals classified as positive by the gold (or reference) standard, who are correctly identified by the study test.

The proportion of relevant studies identified by a search strategy expressed as a percentage of all relevant studies on a given topic. It describes the comprehensiveness of a search method (that is, its ability to identify all relevant studies on a given topic). Highly sensitive strategies tend to have low levels of specificity and vice versa.

A means of representing uncertainty in the results of economic evaluations. Uncertainty may arise from missing data, imprecise estimates or methodological controversy. Sensitivity analysis also allows for exploring the generalisability of results to other settings. The analysis is repeated using different assumptions to examine the effect on the results.

One-way simple sensitivity analysis (univariate analysis): each parameter is varied individually in order to isolate the consequences of each parameter on the results of the study.

Multi-way simple sensitivity analysis (scenario analysis): two or more parameters are varied at the same time and the overall effect on the results is evaluated.

Threshold sensitivity analysis: the critical value of parameters above or below which the conclusions of the study will change are identified.

Probabilistic sensitivity analysis: probability distributions are assigned to the uncertain parameters and are incorporated into evaluation models based on decision analytical techniques (For example, Monte Carlo simulation).

The proportion of individuals classified as negative by the gold (or reference) standard, who are correctly identified by the study test.

Those with an interest in the use of a technology under appraisal or a guideline under development. Stakeholders include manufacturers, sponsors, healthcare professionals, and patient and carer groups.

The ability to demonstrate an association when one exists. Power is related to sample size; the larger the sample size, the greater the power and the lower the risk that a possible association could be missed.

Solid waste that pass through the rectum as bowel movements. Stools are undigested foods, bacteria, mucus, and dead cells.

A research study outcome measuring changes in bowel habit using an aggregate score of stool type, stool consistency, stool frequency, complete evacuation. Scales used vary.

A combination of signs and/or symptoms that forms a distinct clinical picture indicative of a particular disorder.

A generic term to describe methods used for summarising (comparing and contrasting) evidence into a clinically meaningful conclusion in order to answer a defined clinical question. This can include systematic review (with or without meta-analysis), qualitative and narrative summaries.

Research that summarises the evidence on a clearly formulated question according to a predefined protocol using systematic and explicit methods to identify, select and appraise relevant studies, and to extract, collate and report their findings. It may or may not use statistical meta-analysis.

The length of time food takes to pass through the gastrointestinal tract from ingestion to excretion. It is estimated using radio opaque markers and can define three types of delay: right colon (colonic inertial), left colon and recto sigmoid. The exact type of delay may be an important basis for treatment.

The time span used in the NICE appraisal which reflects the period over which the main differences between interventions in health effects and use of healthcare resources are expected to be experienced, and taking into account the limitations of supportive evidence.

Assigning a participant to a particular arm of the trial.

The choices of intervention available.

Any one using the guideline.

A measure of the strength of an individual’s preference for a specific health state in relation to alternative health states. The utility scale assigns numerical values on a scale from 0 (death) to 1 (optimal or ‘perfect’ health). Health states can be considered worse than death and thus have a negative value.

Enhanced perception or enhanced responsiveness within the gut.