Epidemiological Studies: A Practical Guide, 2nd edition

Cover......Page 1
Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Scope of this volume......Page 13
Second edition......Page 16
Part I Introduction......Page 17
1.1a Disease definition......Page 19
1.1b Disease occurrence......Page 20
1.1d Disease outcome......Page 21
1.1e Disease management and disease prevention......Page 22
1.2b Population selection......Page 23
1.2c Information quality......Page 24
1.2f Logistical issues......Page 25
Part II Measuring the occurrence of disease......Page 27
2.1 Incidence......Page 29
2.1a Approaches to measuring incidence......Page 30
2.2 Prevalence......Page 32
2.3 Choice of measure......Page 33
3.1 Introduction......Page 36
3.2a Direct standardisation......Page 37
3.2b Indirect standardisation......Page 38
3.3 Comparison of rates over time......Page 40
3.3a Age-specific rates......Page 41
Part III Studying associations between risk factors and disease......Page 45
4.1 The ecologic study......Page 47
4.2 The migrant study......Page 49
4.3 The cross-sectional study......Page 51
4.4 The case-control study......Page 53
4.5 The cohort study......Page 55
4.6 Choice of study design......Page 57
4.6a Examples of choice of study design......Page 58
5.1a Risk ratios......Page 61
5.1b Rate ratios......Page 62
5.2 Odds ratios......Page 63
5.3 Attributable risks......Page 64
5.5 Categorisation of exposures......Page 65
Part IV Selection of populations and samples to study......Page 67
6 Studies of disease occurrence. I: Identification of the population......Page 69
6.1 Representativeness......Page 70
6.2 Access......Page 71
6.3 Population data accuracy......Page 72
6.4a Sampling from a population......Page 73
7.1 Approaches to measuring incidence......Page 76
7.2 Use of diagnosed cases: retrospective review or prospective notification?......Page 79
7.2a Physician compliance......Page 80
7.3a Case ascertainment......Page 81
7.3b Case verification......Page 82
7.4a Single or duplicate surveys?......Page 83
7.5 Approaches to measuring prevalence......Page 84
7.6 Catchment population methods for measuring prevalence......Page 85
7.7 Population surveys......Page 86
7.8 Other (indirect) measures......Page 87
8.1a Incident or prevalent cases?......Page 90
8.1b Population-based or ‘hospital-based series’......Page 92
8.1c Recruitment of diagnosed cases: using existing databases......Page 93
8.1e Case verification......Page 94
8.1f Exclusion criteria......Page 97
8.2a Strategies for control selection: population-based......Page 98
(ii) Telephone recruitment......Page 100
(i) Disease controls......Page 101
(ii) Family/friend controls......Page 102
8.3 One or two control groups?......Page 103
8.4a Problems with individual matching......Page 104
8.4b Frequency matching......Page 105
8.5 Study size......Page 106
9.1 Retrospective or prospective study cohorts?......Page 109
9.2 How should exposure be categorised?......Page 111
9.2b Ascertainment of exposure status......Page 112
9.3 Study size......Page 113
Part V Information from epidemiological surveys......Page 117
10.1 Interview or subject completing questionnaire?......Page 119
Summary......Page 121
10.2a Open or closed questions?......Page 122
10.2b Questionnaire design......Page 124
11.1 Introduction......Page 127
11.2 Sensitivity and specificity......Page 128
11.3 Validity for variables that are not dichotomous......Page 131
11.4 Possible approaches for independent validation......Page 132
11.5 Misclassification......Page 134
12.1 Introduction......Page 136
12.1a Variation within and between observers......Page 137
12.2 Study designs to measure repeatability......Page 138
12.2a Analysis of repeatability......Page 139
13.2 Reasons for non-participation......Page 144
13.2b Inconvenience......Page 145
13.2e Anxiety about health......Page 147
13.3a Introduction......Page 148
Using existing registers......Page 149
Developing specific information systems......Page 150
13.3c Minimising loss to follow-up......Page 151
14.1 Aims......Page 154
14.1c Study instruments......Page 155
14.1d Other methods of collecting information......Page 156
14.1e Sample size requirements......Page 157
Part VI Analysis and interpretation of epidemiological data......Page 159
15.1a Use of computers......Page 161
15.1b Stages in preparing data for analysis......Page 162
15.2 Initial checking for completeness and accuracy......Page 163
15.4 Development of a data coding schedule......Page 165
15.5 Development of a computer database......Page 167
15.5b In-built range and consistency checks......Page 168
15.6a Immediate data entry......Page 169
15.7 Checking for errors in entered data......Page 170
15.8 Missing data......Page 171
15.9 Recoding of entered data......Page 172
15.10 torage of data and data set......Page 173
16.2 Incidence rates......Page 174
16.2a Confidence interval around an incidence rate......Page 175
16.3 Prevalence (proportions)......Page 176
16.3a Confidence interval around a prevalence (proportion)......Page 177
16.4 Crude, age-specific and standardised rates......Page 179
16.4a Direct standardisation......Page 180
16.4b Indirect standardisation......Page 181
17.1 Introduction......Page 184
17.1a Statistical packages......Page 185
17.2 Effect measurement, interval assessment and significance testing......Page 186
17.3 Analysis of case-control studies......Page 187
17.3a Calculation of confidence interval for an odds ratio......Page 188
17.3b Calculation of odds ratios with multiple levels of exposure......Page 190
Estimate of linear trend......Page 191
17.3c Analysis of matched pairs......Page 193
17.4a Calculation of rate ratio from incidence data......Page 195
Calculation of confidence interval around incidence rate ratio......Page 196
17.4b Calculation of risk ratio estimate from prevalence or cumulative incidence data......Page 197
17.4c Life-table method for incidence data......Page 198
Comparison of survival curves......Page 201
17.5 Conclusion......Page 203
18.1 Introduction......Page 204
Matching......Page 206
18.3 Conduct of study......Page 207
18.4a Baseline comparison of potential confounders......Page 208
18.4b Stratification......Page 209
18.4c Standardisation......Page 213
18.4d Multivariate techniques......Page 215
19.1 Introduction......Page 217
19.1b Non-directional misclassification......Page 218
19.2 Major sources of bias......Page 219
19.3 Selection bias......Page 220
19.3a Non-response bias......Page 221
'Reluctant responders'......Page 223
19.3c Other forms of selection bias......Page 224
19.4a Observer bias......Page 225
19.4b Subject bias......Page 226
19.5 Is an unbiased study ever possible?......Page 228
Part VII Other practical issues......Page 229
20.2 Ethical approval......Page 231
20.3 Ethical constraints in maximising response rate......Page 232
20.3a Opting out or opting in......Page 233
20.4a Legal requirements......Page 234
20.4b Confidentiality of data collected for the study......Page 235
20.4c Access to confidential data from a third party......Page 236
20.5 Detection of previously unrecognised disease......Page 237
20.5a Ascertainment of presymptomatic disorders not requiring intervention......Page 238
20.5b Ascertainment of disorders requiring intervention......Page 239
20.5d Distress amongst participating subjects......Page 240
20.6 Consent......Page 241
21.1 Costs versus design......Page 244
21.2 Costing an epidemiological study......Page 245
21.3 Possibilities for cost containment......Page 249
Data entry......Page 250
21.4a Questionnaire size......Page 251
21.4b Statistical analysis......Page 252
Index......Page 253