The Population at Risk (ประชากรกล่มุ เส่ยี ง) The population at risk (ประชากรกลุ่มเสย่ี ง) The term population-at-risk refers to the group of individuals susceptible to the event of interest (e.g., infection, disease, death) at or during the time period of interest.
The Population at Risk (ประชากรกลุ่มเส่ียง) mid-year population calculation 1. Mid-year 2. National 3. Based on the 3.1 Mid-year population populatio mid-year calculation of data n (July 1) population = (population on January 1) + 1/2 of number of of a given estimates are from the civil births - number of deaths + Number of people made every registration of the moving in - Number of people moving out) of the year 10 years. Ministry of Interior. given year (กระทรวงมหาดไทย) 3.3 Mid-year population 3.2 Mid-year population = 1/2 (population on December 31 of the previous = (population on December 31) - 1/2 of number of year + population on December 31 of the given year) births - number of deaths + Number of people moving in - Number of people moving out) of the given year
Summarize epidemiological measurements Measures of disease frequency Period prevalence 1. Cumulative incidence (CI) 2. Incidence rate 2. Incidence density (ID) or Person-time incidence 3. Attack Rate (อตั ราโจมจบั ) 3.1 Primary 3.2 Secondary
The contents of this chapter 2. The epidemiological measurements 2.2 Measures of association 2.3 Measures of potential impact
The key to epidemiologic analysis is comparison. A measure of association quantifies the relationship between exposure and disease among the two groups.
The measures of association described in the following section compare disease occurrence among one group with disease occurrence in another group. relative risk (risk ratio) odds ratio
RelatRiveelaRtivsek oRrisRkis(คkา่ Rคaวtาioมเ(สRยี่ Rง)ส(มั คพา่ คัทวธา)์ มเสย่ี งสมั พทั ธ์) Relative Risk (RR) A relative risk (RR), also called risk ratio, compares the risk of a health event (disease, injury, risk factor, or death) among one group with the risk among another group. The formula for RR is: Relative Risk (RR) = ������������������������ ������������ ������������������������������������������ (������������������������������������������������������ ������������������������������������������������������������,������������������������������������ ������������������������) ������������ ������������������������������ ������������ ������������������������������������������ ������������������������ ������������ ������������������������������������������ (������������������������������������������������������ ������������������������������������������������������������,������������������������������������ ������������������������) ������������ ������������������������������ ������������ ������������������������������������������������������
Relative Risk or Risk Ratio (RR) (ค่าความเสย่ี งสัมพัทธ์) Relative Risk or Risk Ratio (RR) Interpretation ➢ A risk ratio of 1.0 indicates identical risk among the two groups. ➢ A risk ratio greater than 1.0 indicates an increased risk for the group in the numerator, usually the exposed group. ➢ A risk ratio less than 1.0 indicates a decreased risk for the exposed group, indicating that perhaps exposure actually protects against disease occurrence. Source: https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section2.html
EXAMPLES: Calculating Relative Risk (Risk Ratio) General Format and Notation for a Two-by-Two Table Ill (ป่ วย) Well (ไม่ป่ วย) Total b a+b Exposed (ไดร้ บั ปัจจยั ) a d c+d Unexposed (ไมไ่ ดร้ บั ปัจจยั ) c Total a+c b+d N Relative Risk (RR) = ������������������������ ������������ ������������������������������������������ (������������������������������������������������������ ������������������������������������������������������������,������������������������������������ ������������������������) ������������ ������������������������������ ������������ ������������������������������������������ ������������������������ ������������ ������������������������������������������ (������������������������������������������������������ ������������������������������������������������������������,������������������������������������ ������������������������) ������������ ������������������������������ ������������ ������������������������������������������������������ ������������������������ ������������ ������������������������������������������ among exposed = a ⁄ a+b ������������������������ ������������ ������������������������������������������ among unexposed = c ⁄ c+d
Example A: In an outbreak of COVID-19 among community residents in 2022, 28 of 157 older persons who contacted a COVID-19 patient developed COVID-19, compared with 4 of 137 older persons who uncontacted a COVID-19 patient. These data are summarized in the two-by-two table so-called because it has two rows for the exposure and two columns for the outcome. Here is the general format and notation. Exposed (contacted) Ill (ป่ วย) Well (ไม่ป่ วย) Total Unexposed(uncontacted) 28 (a) 129 (b) 157 (a+b) 4 (c) 133 (d) 137 (c + d) Total 32 (a + c) 262 (b + d) 294 (N) For this example: Risk of COVID-19 among contacted = 28 ⁄ 157 = 0.178 = 17.8% Risk of COVID-19 among uncontacted = 4 ⁄ 137 = 0.029 = 2.9% The risk ratio is simply the ratio of these two risks: Risk ratio = 17.8 ⁄ 2.9 = 6.1 Thus, older people who contacted a COVID-19 patient were 6.1 times as likely to develop COVID-19 as those who uncontacted a COVID-19 patient.
Odds ratio • An odds ratio (OR) is another measure of association that quantifies the relationship between exposure with two categories and health outcomes. Referring to the a Two-by-Two Table, the odds ratio is calculated as No Disease Disease No Disease (-) (+) (-) Disease Exposed (+) (+) Unexposed (-) Exposed (+) Unexposed (-)
Relative Risk or Risk Ratio (RR), Odds ratio (คา่ ความเสี่ยงสัมพทั ธ)์ Relative Risk or Risk Ratio (RR), Odds ratio Interpretation ➢ A odds ratio of 1.0 indicates identical risk among the two groups. ➢ A odds ratio greater than 1.0 indicates an increased risk for the group in the numerator, usually the exposed group. ➢ A odds ratio less than 1.0 indicates a decreased risk for the exposed group, indicating that perhaps exposure actually protects against disease occurrence. Source: https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section2.html
➢ Attributable Risk (AR), ➢ Attributable Risk Percent (AR%), ➢ Population Attributable Risk (PAR), ➢ Population Attributable Risk Percent (PAR%)
Attributable risk (AR) Source: https://www.rama.mahidol.ac.th/ceb/sites/default/files/public/pdf/ACADEMIC/2016/race612/Handout _Measurement%20in%20Epidemiology2016.pdf
Measures of Public Health Impact (การวดั ผลกระทบทเ่ี กดิ ข้นึ กบั ชมุ ชน) For example, Breast cancer 2. has many causes, including smoking cigarettes and exposure to the hormone Estrogen. One study showed that the AR% for cigarette smoking and breast cancer was 65%. คือ การคาดคะเนรอ้ ยละของอบุ ตั ิการของโรคในกลม่ สมั ผสั ส่งิ ท่ีคาดวา่ กอ่ โรค Source: https://www.rama.mahidol.ac.th/ceb/sites/default/files/public/pdf/ACADEMIC/2016/race 612/Handout_Measurement%20in%20Epidemiology2016.pdf
3. Population Attributable Risk (PAR) 3. Source: https://www.rama.mahidol.ac.th/ceb/sites/default/files/public/pdf/ACADEMIC/2016/race612/Handout _Measurement%20in%20Epidemiology2016.pdf
4. X 100
The epidemiological measurements 2.1 Measures 2.2 Measures of of disease association frequency Prevalence Incidence RR Risk ratio Odd ratio
Chapter Contents 1 Health Index (ดชั นอี นามยั ) 2 Vital statistics (สถติ ชิ พี )
Concepts Health Index Health Indicators (เครอ่ื งชว้ี ดั สุขภาพ) (ดชั นีอนามยั ) Vital statistics (สถติ ชิ พี ) Health index and vital statistics are health indicators that show information about the health situation of the community, sub-district, province, and country.
Basic concepts of the health index Health Index - Indicator of community health condition in various aspects
Basic concepts of the health index Health Index • indicators of the health condition of a particular community should cover both (ดชั นีอนามยั ) the direct measurement of the sanitary condition and the determinants or various elements that influence the state of health Vital statistics • Vital statistics mean numerical data relating to events that are important to people's lives and (สถิติชีพ) health conditions at a particular time, death, illness and is an indicator of people's health status.
The significant indicators to measure the health condition of the people are as follows: Group 1 Indicators of community characteristics 1.1 Characteristics of the structure of the people in the community 1.2 Characteristics of economic, society, and culture Group 2 Indicators of quality of life of the population 2.1 Quality of the environment 2.2 The quality of the population Group 3 Health indicators 3.1 Indicators of positive health conditions 3.2 Indicators of negative health conditions
Statistics of calculation of vital statistics and health index 1. Rate (อตั รา) 2. Ratio (อตั ราส่วน) 3. Index (ดชั นี) 4. Proportion (สดั ส่วน) • Index = ������ × ������ • Rate = ������ • Ratio = ������ • Proportion = ������ ������+������ ������+������+������+������ ������+������ ������ • (������ is a constant, it can • Rate = ������ × • or ������ : ������ be 100, 1000, 10,000, • = ������ × ������ 100,000,…) ������+������+������+������ ������+������ Ratio = ������ × ������ where a + b is a ������ • derivative or estimate. ������ • (where ������ is a constant, usually 100) • (������ is a constant, it can be 100, 1000, 10,000, 100,000,…)
1. Measure of morbidity (การวดั การป่วย) 2. Measure of mortality (การวดั การตาย) 3. Dependency ratio (อตั ราสว่ นพง่ึ พงิ )
1. Measure of morbidity (เคร่อื งช้วี ัดปริมาณการเจ็บปว่ ย) 1. Prevalence rate 2. Incidence rate
1. Measure of morbidity: 1.1 Prevalence rate Example 1 A daily activity record form of a public health hospital in November 2021 summarizes the results of dengue fever control as follows: 1. Patients in responsibility are quoted as 25 people. 2. Patients registered as new patients are 30 cases 3. The population in that sub-district in 2021 has a total of 32,000 people. Therefore, the prevalence rate of dengue fever in November 2021 Prevalence rate = (25+30) ×10,000 32,000 = 17.18 per 10,000 populations
1. Measure of morbidity: 1.2 Incidence rate Example 2 A daily activity record form of a public health hospital in November 2021 summarizes the results of dengue fever control as follows: 1. Patients in responsibility are quoted as 25 people. 2. Patients registered as new patients are 30 cases 3. The population in that sub-district in 2021 has a total of 32,000 people. Therefore, the incidence rate of dengue fever in November 2021 Incidence rate = 30 ×10,000 32,000 = 9.37 per 10,000 populations
Measure of morbidity: 3 Attack Rate (อตั ราโจมจับ) Source: Primary Attack Rate https://www.cdc.gov/c sels/dsepd/ss1978/les son3/section2.html จำนวนผู้ป่วยรำยแรก ๆ (∗) ที่เกิดขน้ึ ในช่วงเวลำทีศ่ ึกษำ × 100 = = จำนวนประชำกรท่เี สีย่ งในระยะเวลำเดยี วกัน (*) หมายถงึ ผปู้ ว่ ยรายแรกที่พบและนาโรคเขา้ มาในครอบครัวหรอื ชมุ ชน Secondary Attack Rate * == แลว้ เกดิ กำรปว่ ยข้ึนภำยในชว่ งระยะฟกั ตวั ของโรค∗ ** × 100 จำนวนผู้ท่ีมีภมู ไิ วรับท่ีสัมผัสกับผูป้ ่วยรำยแรก∗∗ * กลุ่ม ผู้ป่วยที่อาจไดร้ ับเช้ือจากกลุ่มผู้ปว่ ยปฐมภูมิ ** ไม่นบั ผปู้ ว่ ยรายแรก (หรือชุดแรก) และรายท่มี ีภูมิต้านทาน
EXAMPLE 3-4: Calculating Attack Rate Ex.3 …. Consider an outbreak of chickenpox in which 15 students in 15 different classrooms all became ill. If the population of the school was 1,000, then Primary attack rate = (15 ⁄ 1,000) × 100 = 1.5% Ex.4 …. One incubation period later, 20 persons in the same classrooms as these “primary” cases developed chickenpox. If the 15 classrooms included 1,000 students, calculate the secondary attack rate. Secondary attack rate = (20 ⁄ (1,000 − 15)) × 100 = (20 ⁄ 985) × 100 = 2.03%
2. Measure of mortality: 2.1 Crude death rate 2.1 Crude death rate refers to the rate representing the number of all-cause deaths per total population /mid-year population over a period of time. (usually for a period of 1 year) = all−cause deaths in period of time total population /mid−year population over a period of time × ������ The value of ������ (constant) can be 100, 1,000, 10,000 EXAMPLE 5: In a sub-district, 28 people died in 2021, and the mid-year population of a sub-district was 32,000. Crude death rate = 28 × 10,000 32,000 = 8.75 per 10,000 populations
2. Measure of mortality: 2.2 Specific Death Rate (SDR) 2.2.1 Age-specific death rate (ASDR)/Age-specific mortality rate ASDR = # of death in a speci������������������ ������������������ ������������������������������ × ������ number of persons in that age group in the population EXAMPLE 6: Number of deaths in the age group 0-5 in 2021 = 150 Estimated 2021 mid-year population in the age group 0-5 = 20,000 The age-specific death rate for the age group 0-5 in 2021 is calculated using formula above as: ASDR = 150 × 1,000 20,000 = 7.5 per 1,000 populations
Fre2qu.eMntlyeaUseudreMeoafsumreos rotf aMloitrtyality Measure Numerator Denominator K • 1.Crude • Total number of • Mid-interval • 1,000 or death rate deaths during a population • 100,000 given time interval ▪ 2. Cause- ▪ Mid-interval ▪ 100,000 specific ▪ Number of population death rate deaths assigned to a specific cause during a given time interval
Frequently Used Measures of Mortality Measure Numerator Denominator K • 3. Maternal • Number of deaths • Number of live • 100,000 mortality assigned to births during the rate pregnancy-related same time interval causes during a 4. Death-to- given time interval ▪ Number of new ▪ 100 case ratio cases of same อตั ราสว่ นการเสยี ชีวิต (42 days or 6 weeks disease reported ของโรค after delivery) during the same time interval ▪ Number of deaths assigned to a specific cause during a given time interval
Frequently Used Measures of Mortality Measure Numerator Denominator K • 5. Fetal • Number of resident • Number of resident • 1,000 mortality fetal deaths in a live births plus fetal rate specified geographic deaths for the same area (country, state, geographic area อตั ราเดก็ เกิดไรช้ ีพ county, etc.) 6. Neonatal ▪ Number of deaths ▪ Number of live ▪ 1,000 births during the mortality rate among children same time (อตั ราการตายของ ▪ < 28 days of age interval ทารกแรกเกิด) during a given time interval
Frequently Used Measures of Mortality Measure Numerator Denominator K • 7 . Infant • Number of deaths • Number of resident •1,000 mortality among children < 1 live births during rate year of age during a the same time given time interval interval • (อตั ราการตาย ของทารก)
The formula for the dependency ratio is – (the number of people aged between 0 and 15 + the number of people aged 60 and above) divide by the total population between 16 and 59, times by 100. (#people aged between 0 − 15) + (#people aged 60 and above) X 100 total population age 16 − 59 in a period of time
1. Measure of morbidity Prevalence Rate Incidence Rate Attack Rate 2. Measure of mortality [The Division of Vital Statistics (DVS)] Source: https://www- doh.state.nj.us /doh- shad/view/sha redstatic/Fetal MortalityRate. pdf
observation without manipulation Case- 1. Start from the outcome control retrospective to exposure study (factor) 2. Initially, the diseased Source: https://deakin.libguides.com/quantitative-study-designs/casecontrol population was divided into 2 groups, namely the diseased group (case) and the group without the disease (control or non-case).
Study design Time Case-control study Past Present Future Search for risk Selection samples factors (case and control) retrospective Initially the Study (Onset of study) End of Study
The nature of the case-control study observation without manipulation Exposed (+) retrospective Case Case Non-exposured (-) (diseased) (+) Population Exposed (+) retrospective control Non Case Population Non-exposured (-) (non-diseased) (-) retrospective Initially the Study (Onset of study) End of Study
Steps for conducting a case-control study (retrospective study) 1. Formulation of 2. Selection of samples of 3. Data Collection hypothesis and disease (patients) interested study scope in studying (case) and control group (control) 5. Conclusion 4. Data Analysis and Interpretation
Search
Read the Text Version
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
- 102
- 103
- 104
- 105
- 106
- 107
- 108
- 109
- 110
- 111
- 112
- 113
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151
- 152
- 153
- 154
- 155
- 156
- 157
- 158
- 159
- 160
- 161
- 162
- 163
- 164
- 165
- 166
- 167
- 168
- 169
- 170
- 171
- 172
- 173
- 174
- 175
- 176
- 177
- 178
- 179
- 180
- 181
- 182
- 183
- 184
- 185
- 186
- 187
- 188
- 189
- 190
- 191
- 192
- 193
- 194
- 195
- 196
- 197
- 198
- 199
- 200
- 201
- 202
- 203
- 204
- 205
- 206
- 207
- 208
- 209
- 210
- 211
- 212
- 213
- 214
- 215
- 216
- 217
- 218
- 219
- 220
- 221
- 222
- 223
- 224
- 225
- 226
- 227
- 228
- 229
- 230
- 231
- 232
- 233
- 234
- 235
- 236
- 237
- 238
- 239
- 240
- 241
- 242
- 243
- 244
- 245
- 246
- 247
- 248
- 249
- 250
- 251
- 252
- 253
- 254
- 255
- 256
- 257
- 258
- 259
- 260
- 261
- 262
- 263
- 264
- 265
- 266
- 267
- 268
- 269
- 270
- 271
- 272
- 273
- 274
- 275
- 276
- 277
- 278
- 279
- 280
- 281
- 282
- 283
- 284
- 285
- 286
- 287
- 288
- 289
- 290
- 291
- 292
- 293
- 294
- 295
- 296
- 297