Quality of life the assessment, analysis and reporting of patient-reported outcomes

Preface to the third edition xiii     Preface to the second edition xv     Preface to the fi rst edition xvii     List of abbreviations xix     PART 1 Developing and Validating Instruments for Assessing Quality of Life and Patient-Reported Outcomes     1 Introduction 3     1.1 Patient  ]reported outcomes 3     1.2 What is a patient  ]reported outcome? 4     1.3 What is quality of life? 4     1.4 Historical development 6     1.5 Why measure quality of life? 9     1.6 Which clinical trials should assess QoL? 17     1.7 How to measure quality of life 18     1.8 Instruments 19     1.9 Computer  ]adaptive instruments 32     1.10 Conclusions 32     2 Principles of measurement scales 35     2.1 Introduction 35     2.2 Scales and items 35     2.3 Constructs and latent variables 36     2.4 Single global questions versus multi  ]item scales 37     2.5 Single  ]item versus multi  ]item scales 40     2.6 Effect indicators and causal indicators 42     2.7 Psychometrics, factor analysis and item response theory 48     2.8 Psychometric versus clinimetric scales 52     2.9 Suffi cient causes, necessary causes and scoring items 53     2.10 Discriminative, evaluative and predictive instruments 54     2.11 Measuring quality of life: refl ective, causal and composite indicators? 55     2.12 Further reading 56     2.13 Conclusions 56     3 Developing a questionnaire 57     3.1 Introduction 57     3.2 General issues 58     3.3 Defining the target population 58     3.4 Phases of development 59     3.5 Phase 1: Generation of issues 61     3.6 Qualitative methods 63     3.7 Sample sizes 66     3.8 Phase 2: Developing items 68     3.9 Multi  ]item scales 72     3.10 Wording of questions 73     3.11 Face and content validity of the proposed questionnaire 74     3.12 Phase 3: Pre  ]testing the questionnaire 74     3.13 Cognitive interviewing 77     3.14 Translation 80     3.15 Phase 4: Field  ]testing 80     3.16 Conclusions 86     3.17 Further reading 87     4 Scores and measurements: validity, reliability, sensitivity 89     4.1 Introduction 89     4.2 Content validity 90     4.3 Criterion validity 94     4.4 Construct validity 96     4.5 Repeated assessments and change over time 104     4.6 Reliability 104     4.7 Sensitivity and responsiveness 117     4.8 Conclusions 124     4.9 Further reading 124     5 Multi  ]item scales 125     5.1 Introduction 125     5.2 Significance tests 126     5.3 Correlations 127     5.4 Construct validity 133     5.5 Cronbach   s    and internal consistency 139     5.6 Validation or alteration? 143     5.7 Implications for formative or causal items 144     5.8 Conclusions 147     6 Factor analysis and structural equation modelling 149     6.1 Introduction 149     6.2 Correlation patterns 150     6.3 Path diagrams 152     6.4 Factor analysis 154     6.5 Factor analysis of the HADS questionnaire 154     6.6 Uses of factor analysis 159     6.7 Applying factor analysis: Choices and decisions 161     6.8 Assumptions for factor analysis 167     6.9 Factor analysis in QoL research 171     6.10 Limitations of correlation-based analysis 172     6.11 Formative or causal models 173     6.12 Confirmatory factor analysis and structural equation modelling 176     6.13 Chi-square goodness-of-fit test 178     6.14 Approximate goodness-of-fit indices 180     6.15 Comparative fit of models 181     6.16 Difficulty-factors 182     6.17 Bifactor analysis 183     6.18 Do formative or causal relationships matter? 186     6.19 Conclusions 187     6.20 Further reading, and software 188     7 Item response theory and differential item functioning 189     7.1 Introduction 189     7.2 Item characteristic curves 191     7.3 Logistic models 193     7.4 Polytomous item response theory models 196     7.5 Applying logistic IRT models 197     7.6 Assumptions of IRT models 205     7.7 Fitting item response theory models: Tips 208     7.8 Test design and validation 209     7.9 IRT versus traditional and Guttman scales 209     7.10 Differential item functioning 210     7.11 Sample size for DIF analyses 218     7.12 Quantifying differential item functioning 219     7.13 Exploring differential item functioning: Tips 219     7.14 Conclusions 221     7.15 Further reading, and software 222     8 Item banks, item linking and computer-adaptive tests 223     8.1 Introduction 223     8.2 Item bank 224     8.3 Item evaluation, reduction and calibration 226     8.4 Item linking and test equating 228     8.5 Test information 231     8.6 Computer-adaptive testing 232     8.7 Stopping rules and simulations 235     8.8 Computer-adaptive testing software 236     8.9 CATs for PROs 237     8.10 Computer-assisted tests 238     8.11 Short-form tests 239     8.12 Conclusions 239     8.13 Further reading 240     PART 2 Assessing, Analysing and Reporting Patient-Reported Outcomes and the Quality of Life of Patients     9 Choosing and scoring questionnaires 243     9.1 Introduction 243     9.2 Finding instruments 244     9.3 Generic versus specific 245     9.4 Content and presentation 246     9.5 Choice of instrument 247     9.6 Scoring multi-item scales 250     9.7 Conclusions 256     9.8 Further reading 257     10 Clinical trials 259     10.1 Introduction 259     10.2 Basic design issues 260     10.3 Compliance 262     10.4 Administering a quality  ]of  ]life assessment 268     10.5 Recommendations for writing protocols 270     10.6 Standard operating procedures 280     10.7 Summary and checklist 281     10.8 Further reading 282     11 Sample sizes 283     11.1 Introduction 283     11.2 Signifi cance tests, p  ]values and power 284     11.3 Estimating sample size 284     11.4 Comparing two groups 289     11.5 Comparison with a reference population 298     11.6 Non  ]inferiority studies 298     11.7 Choice of sample size method 301     11.8 Non  ]Normal distributions 302     11.9 Multiple testing 303     11.10 Specifying the target difference 305     11.11 Sample size estimation is pre  ]study 305     11.12 Attrition 306     11.13 Circumspection 306     11.14 Conclusion 306     11.15 Further reading 307     12 Cross  ]sectional analysis 309     12.1 Types of data 309     12.2 Comparing two groups 312     12.3 Adjusting for covariates 324     12.4 Changes from baseline 330     12.5 Analysis of variance 331     12.6 Analysis of variance models 336     12.7 Graphical summaries 337     12.8 Endpoints 342     12.9 Conclusions 343     13 Exploring longitudinal data 345     13.1 Area under the curve 345     13.2 Graphical presentations 348     13.3 Tabular presentations 358     13.4 Reporting 360     13.5 Conclusions 365     14 Modelling longitudinal data 367     14.1 Preliminaries 367     14.2 Auto-correlation 368     14.3 Repeated measures 373     14.4 Other situations 388     14.5 Modelling versus area under the curve 389     14.6 Conclusions 390     15 Missing data 393     15.1 Introduction 393     15.2 Why do missing data matter? 396     15.3 Types of missing data 400     15.4 Missing items 403     15.5 Methods for missing items within a form 404     15.6 Missing forms 408     15.7 Methods for missing forms 410     15.8 Simple methods for missing forms 410     15.9 Methods of imputation that incorporate variability 415     15.10 Multiple imputation 421     15.11 Pattern mixture models 422     15.12 Comments 424     15.13 Degrees of freedom 425     15.14 Sensitivity analysis 426     15.15 Conclusions 426     15.16 Further reading 427     16 Practical and reporting issues 429     16.1 Introduction 429     16.2 The reporting of design issues 430     16.3 Data analysis 430     16.4 Elements of good graphics 436     16.5 Some errors 440     16.6 Guidelines for reporting 442     16.7 Further reading 445     17 Death, and quality-adjusted survival 447     17.1 Introduction 447     17.2 Attrition due to death 448     17.3 Preferences and utilities 449     17.4 Multi-attribute utility (MAU) measures 453     17.5 Utility-based instruments 454     17.6 Quality-adjusted life years (QALYs) 456     17.7 Utilities for traditional instruments 457     17.8 Q-TWiST 462     17.9 Sensitivity analysis 467     17.10 Prognosis and variation with time 470     17.11 Alternatives to QALY 472     17.12 Conclusions 473     17.13 Further reading 474     18 Clinical interpretation 475     18.1 Introduction 475     18.2 Statistical signifi cance 476     18.3 Absolute levels and changes over time 477     18.4 Threshold values: percentages 478     18.5 Population norms 479     18.6 Minimal important difference 488     18.7 Anchoring against other measurements 492     18.8 Minimum detectable change 493     18.9 Expert judgement for evidence-based guidelines 494     18.10 Impact of the state of quality of life 495     18.11 Changes in relation to life events 496     18.12 Effect size statistics 498     18.13 Patient variability 505     18.14 Number needed to treat 506     18.15 Conclusions 509     18.16 Further reading 509     19 Biased reporting and response shift 511     19.1 Bias 511     19.2 Recall bias 512     19.3 Selective reporting bias 513     19.4 Other biases affecting PROs 514     19.5 Response shift 516     19.6 Assessing response shift 521     19.7 Impact of response shift 523     19.8 Clinical trials 523     19.9 Non  ]randomised studies 525     19.10 Conclusions 526     20 Meta  ]analysis 527     20.1 Introduction 527     20.2 Defining objectives 528     20.3 Defining outcomes 528     20.4 Literature searching 528     20.5 Assessing quality 529     20.6 Summarising results 533     20.7 Measures of treatment effect 534     20.8 Combining studies 537     20.9 Forest plot 542     20.10 Heterogeneity 542     20.11 Publication bias and funnel plots 544     20.12 Conclusions 545     20.13 Further reading 546     Appendix 1: Examples of instruments 547     Generic instruments     E1 Sickness Impact Profi le (SIP) 549     E2 Nottingham Health Profi le (NHP) 551     E3 SF36v2TM Health Survey Standard Version 552     E4 EuroQoL EQ-5D-5L 555     E5 Patient Generated Index of quality of life (PGI) 557     Disease-specific instruments 559     E6 European Organisation for Research and Treatment of Cancer QLQ-C30 (EORTC QLQ-C30) 559     E7 Elderly cancer patients module (EORTC QLQ-ELD14) 561     E8 Functional Assessment of Cancer Therapy     General (FACT-G) 562     E9 Rotterdam Symptom Checklist (RSCL) 564     E10 Quality of Life in Epilepsy Inventory (QOLIE-89) 566     E11 Paediatric Asthma Quality of Life Questionnaire (PAQLQ) 570     Domain-specifi c instruments 573     E12 Hospital Anxiety and Depression Scale (HADS) 573     E13 Short-Form McGill Pain Questionnaire (SF-MPQ) 574     E14 Multidimensional Fatigue Inventory (MFI-20) 575     ADL and disability 577     E 15 (Modifi ed) Barthel Index of Disability (MBI) 577     Appendix 2: Statistical tables 579     Table T1: Normal distribution 579     Table T2: Probability points of the Normal distribution 581     Table T3: Student   s t  ]distribution 582     Table T4: The   2 distribution 583     Table T5: The F  ]distribution 584     References 585     Index 613