Table 1.
Characteristics of cases and controls
| Variable | Category | Case | Control | ||
|---|---|---|---|---|---|
| n | % | n | % | ||
| Total | 395 | 1308 | |||
| Age group | <21 | 13 | 3.3 | 140 | 10.7 |
| 21 to 30 | 130 | 32.9 | 396 | 30.3 | |
| 31 to 40 | 97 | 24.6 | 238 | 18.2 | |
| 41 to 50 | 76 | 19.2 | 235 | 18.0 | |
| 51 to 60 | 55 | 13.9 | 197 | 15.1 | |
| 61 and above | 24 | 6.1 | 102 | 7.8 | |
| Gender (Female/Male) | Female | 142 | 35.9 | 503 | 38.5 |
| Ethnicity | Chinese | 265 | 67.1 | 781 | 59.7 |
| Malay | 33 | 8.4 | 240 | 18.3 | |
| Indian | 57 | 14.4 | 193 | 14.8 | |
| Other | 40 | 10.1 | 94 | 7.2 | |
| Home address region | SW | 52 | 13.4 | 204 | 15.8 |
| C | 204 | 52.4 | 646 | 50.0 | |
| NW | 62 | 15.9 | 264 | 20.4 | |
| NE | 61 | 15.7 | 158 | 12.2 | |
| SE | 10 | 2.6 | 20 | 1.5 | |
| Country of origin (Singapore/Others) | Singapore | 248 | 62.8 | 909 | 69.5 |
| Healthcare recruitment site | A | 217 | 54.9 | 807 | 61.7 |
| B | 12 | 3.0 | 24 | 1.8 | |
| C | 34 | 8.6 | 180 | 13.8 | |
| D | 28 | 7.1 | 63 | 4.8 | |
| E | 33 | 8.4 | 193 | 14.8 | |
| F | 71 | 18.0 | 41 | 3.1 | |
| Medical history (Diabetes/Hypertension/IHD/Malignancy/Steroid treatment) [No/Yes] | No | 338 | 85.6 | 1099 | 84.1 |
| Self-reported history of past dengue infection (No/Yes) | No | 378 | 96.7 | 1235 | 95.0 |
| Dwelling type | Multistorey public flats | 291 | 73.7 | 1082 | 82.8 |
| Multistorey private flats | 18 | 4.6 | 64 | 4.9 | |
| Landed houses | 35 | 8.9 | 83 | 6.4 | |
| Foreign (construction) workers dormitory/hostel | 51 | 12.9 | 77 | 5.9 | |
| Dwelling floor level | mean floor | 6 | 4a | 7 | 4a |
| Travel history (No/Yes) | No | 342 | 86.6 | 1101 | 84.3 |
| Type of employment (Indoor/Outdoor/Both) and Primary mode of transportation to work (Public-train or bus/Private-taxi or car/Walking) | Unemployed | 90 | 22.8 | 269 | 20.7 |
| Indoor & Public | 90 | 22.8 | 410 | 31.6 | |
| Indoor & Private | 24 | 6.1 | 84 | 6.5 | |
| Indoor & Walking | 10 | 2.5 | 41 | 3.2 | |
| Outdoor & Public | 37 | 9.4 | 108 | 8.3 | |
| Outdoor & Private | 24 | 6.1 | 51 | 3.9 | |
| Outdoor & Walking | 19 | 4.8 | 29 | 2.2 | |
| Both & Public | 52 | 13.2 | 208 | 16.0 | |
| Both & Private | 35 | 8.9 | 80 | 6.2 | |
| Both & Walking | 14 | 3.5 | 19 | 1.5 | |
| Self-reported history of mosquito bite (No/Yes) | No | 291 | 73.7 | 994 | 76.5 |
| Self-reported history of household dengue (No/Yes) | No | 372 | 94.4 | 1294 | 99.2 |
| Self-reported history of household fever (No/Yes) | No | 295 | 74.7 | 1076 | 82.6 |
aStandard Deviation