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viii Glossary and list of abbreviations Glossary continued Confounding (1) The masking of an actual association or (2) false demonstration of an apparent association between the study variables when no real association between them exists. Construct validity An instrument exhibits this if it is demonstrated that it correlates with other trusted measures of the same effect being measured and that it can discriminate between groups with known differences. Cost–benefit analysis An attempt to give the consequences of the alternative interventions a monetary value. In this way, the consequences can be more easily compared with the costs of the intervention. This involves measuring individuals’ ‘willingness to pay’ for given outcomes, and can be difficult. Cost–consequence analysis Costs are reported separately from health effects. Cost-effectiveness analysis The consequences of the alternatives are measured in natural units, such as years of life gained. The consequences are not given a monetary value. Cost-effectiveness acceptability curve A graphical representation of the probability of an intervention being cost-effective over a range of monetary values for society’s willingness to pay for an additional unit of health gain. Cost minimisation When two alternatives are found to have equal efficacy or outcomes (consequences). Therefore, the only difference between the two is cost. This is sometimes considered to be a subtype of cost-effectiveness analysis. Cost–utility analysis The consequences of alternatives are measured in ‘health state preferences’, which are given a weighting score. In this type of analysis, different consequences are valued in comparison with each other, and the outcomes (e.g. life-years gained) are adjusted by the weighting assigned. In this way, an attempt is made to value the quality of life associated with the outcome so that life-years gained become quality-adjusted life-years gained. Crossover trial A type of clinical trial comparing two or more interventions in which the participants, upon completion of the course of one treatment, are switched to another. For example, for a comparison of treatments A and B, half the participants are randomly allocated to receive them in the order A, B and half to receive them in the order B, A. A problem with this design is that the effects of the first treatment may carry over into the period when the second is given. Discounting The process of converting future pounds sterling and future health effects to their present value. Discriminant validity An instrument exhibits this for the extent to which it does not correlate with variables and measures thought to be unrelated to the construct being measured. Dominance The state when an intervention under study is both less costly and more effective than the comparator(s). Economic evaluation Comparative analysis of alternative course of action in terms of both their costs and effects. Effectiveness The extent to which a specific intervention, when used under ordinary circumstances, does what it is intended to do. Extended dominance The state when a strategy is both more costly and less effective than a linear combination of two other strategies with which it is mutually exclusive. External validity The ability to generalise the results from a particular experiment to a larger population. First-line treatment The first regimen given to patients Incidence The number of new cases of a disease or event in a population during a specific period of time. Incremental cost-effectiveness ratio An expression of the additional cost of health gain associated with an intervention relative to an appropriate comparator. Expressed as the difference in mean costs (relative to the comparator) divided by the difference in mean continued
Glossary continued effects. Sometimes expressed with confidence intervals. Intention-to-treat An ITT analysis is one in which all the participants in a trial are analysed according to the intervention to which they were allocated, whether they received it or not. ITT analyses are favoured in assessments of effectiveness as they mirror the noncompliance and treatment changes that are likely to occur when the intervention is used in practice, and because of the risk of attrition bias when participants are excluded from the analysis. Internal validity The degree to which a study is logically sound and free of confounding variables. Markov Chain Monte Carlo A mathematical model containing a finite number of mutually exclusive and exhaustive health states, with uniform time periods and in which the probability of movement from one state to another depends on the current state and remains constant over time. Methodological quality (synonyms: validity, internal validity) The extent to which the design and conduct of a study are likely to have prevented systematic errors (bias). Variation in quality can explain variation in the results of studies included in a systematic review. More rigorously designed (better ‘quality’) trials are more likely to yield results that are closer to the ‘truth’. Meta-analysis The statistical pooling of the results of a collection of related individual studies, to increase statistical power and synthesise their findings. Mixed treatment comparison Mixed treatment comparison is a form of metaanalysis used to strengthen inference concerning the relative efficacy of two treatments. It uses data based on direct comparisons (A versus B and B versus C trials) and indirect comparisons (A versus C trials); also, it facilitates simultaneous inference regarding all treatments in order to select the best treatments. p-Value In the context of significant tests, the p-value represents the probability that a given © Queen’s Printer and Controller of HMSO 2006. All rights reserved. Health Technology Assessment 2006; Vol. 10: No. 23 difference is observed in a study sample, when such a difference does not exist in the relevant population. Small p-values indicate stronger evidence to reject the null hypothesis of no difference. Parallel group trial (synonym: independent group design) A trial that compares two groups of people, one of which receives the intervention of interest and one of which is a control group. Some parallel trials have more than two comparison groups and some compare different interventions without including a non-intervention control group. Prevalence The measure of the proportion of people in a population who have some attribute or disease at a given point in time or during some time period. Oppositional defiant disorder A mental disorder characterised by a pattern of negativistic, defiant, disobedient and hostile behaviour towards authority figures as evident in such behaviour as temper tantrums, argumentativeness, refusing to comply with requests and deliberately annoying others. Placebo An inactive substance or procedure administered to a patient, usually to compare its effects with those of a real drug or other intervention, but sometimes for the psychological benefit to the patient through a belief that they are receiving treatment. Placebos are used in clinical trials to blind people to their treatment allocation. Placebos should be indistinguishable from the active intervention to ensure adequate blinding. Quality of life A concept incorporating all the factors that might impact on an individual’s life, including factors such as the absence of disease or infirmity and also other factors which might affect their physical, mental and social well-being. Quality-adjusted life-year An index of health gain where survival duration is weighted or adjusted by the patient’s quality of life during the survival period. QALYs have the advantage of incorporating changes in both quantity (mortality) and quality (morbidity) of life. continued ix
Page 1 and 2: A systematic review and economic mo
Page 3 and 4: A systematic review and economic mo
Page 5 and 6: Objectives: To assess the clinical
Page 7 and 8: Glossary and list of abbreviations
Page 9: Glossary Adverse effect An abnormal
Page 13 and 14: Glossary continued point between tw
Page 15 and 16: Background Attention deficit hypera
Page 17 and 18: mean differences with 95% confidenc
Page 19: This review examines the clinical a
Page 22 and 23: 4 Background E. Symptoms should not
Page 24 and 25: 6 Background Concerta XL Concerta X
Page 26 and 27: 8 Methods for reviewing effectivene
Page 28 and 29: 10 Methods for reviewing effectiven
Page 31 and 32: Quantity and quality of research av
Page 33 and 34: TABLE 1 The quality of included stu
Page 35 and 36: TABLE 2 An overview of trials inclu
Page 37 and 38: TABLE 2 An overview of trials inclu
Page 39 and 40: TABLE 3 MPH low dose (≤15 mg/day)
Page 41 and 42: Quality of life Only one of the 12
Page 43 and 44: TABLE 5 MPH medium dose (15-30 mg/d
Page 45 and 46: Hyperactivity All nine studies that
Page 47 and 48: TABLE 6 Results for hyperactivity [
Page 49 and 50: Study Parallel trials Buitelaar 199
Page 51 and 52: TABLE 8 Results for hyperactivity [
Page 53 and 54: Study Parallel trials Gittelman-Kle
Page 55 and 56: TABLE 11 MPH high dose (>30 mg/day)
Page 57 and 58: TABLE 14 ER-MPH medium dose (20-40
Page 59 and 60: Study Crossover trials Stein 2003 S
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TABLE 19 Results for hyperactivity
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TABLE 22 MPH low dose (≤ 15 mg/da
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TABLE 24 MPH medium dose (15-30 mg/
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assessed by parents and teachers. I
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TABLE 30 DEX medium dose (10-20 mg/
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TABLE 38 DEX medium dose (10-20 mg/
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TABLE 41 DEX-SR plus non-drug inter
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Study Michelson 2001 [0.5] Michelso
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Hyperactivity Five trials (publishe
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TABLE 47 IR-MPH low-dose (≤ 15 mg
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STP. 77,78 Neither examined hyperac
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Adverse events No significant diffe
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did report that there were no signi
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Summary The one study in this categ
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showed persisting significant super
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easily rectified with dosage adjust
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Aim The aim of this chapter is to r
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only level of social disability tha
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did not include a ‘global’ HRQo
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might decrease but costs would be e
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1st line pharmacotherapy Response,
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TABLE 70 Data for weighted average
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The probabilistic results were used
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The review also uncovered a mis-ref
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TABLE 77 Results of sensitivity ana
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TABLE 80 Response a rates (%) estim
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TABLE 82 Drug costs used in the cos
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The review of the economic evidence
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Extrapolation A secondary analysis
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economic model rests on the assumpt
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TABLE 87 Data used in calculating w
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not fully probabilistic. The averag
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Probability cost-effective 1.0 0.9
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TABLE 93 Results of sensitivity ana
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Base case model Responder to MPH Re
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TABLE 96 Results of the sensitivity
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The same method for synthesising th
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TABLE 103 Results of the economic m
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of the 64 identified in the clinica
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126 Discussion impact of active dru
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MPH, DEX and ATX improve hyperactiv
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1. National Institute for Clinical
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tutoring on the behavior and achiev
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91. Stein MA, Blondis TA, Schnitzle
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140. Hill P, Taylor E. An auditable
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189. Francis S, Fine J, Tannock R.
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235. Rhodes SM, Coghill DR, Matthew
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hyperactive boys: comparative and c
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This version of HTA monograph volum
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380 Health Technology Assessment Pr
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382 Health Technology Assessment Pr
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