Frequency for socioeconomic status (SES) variables for cases and controls in the INTERHEART study
| Controls | Cases | χ2 | p Value | |
| No (%) | No (%) | |||
| Education | ||||
| Trade school/college/university | 5370 (36.7) | 3557 (29.1) | ||
| 9–12 years | 3677 (25.2) | 3177 (26.0) | ||
| ⩽8 years | 5575 (38.1) | 5508 (45.0) | 190.6 | <0.0001 |
| Household income | ||||
| Quintile 4, 5 | 4266 (29.6) | 3119 (25.9) | ||
| Quintile 3 | 2969 (20.6) | 2567 (21.3) | ||
| Quintile 1, 2 | 7168 (49.8) | 6360 (52.8) | 40.6 | <0.0001 |
| Possessions | ||||
| ⩽2 | 2003 (13.7) | 1795 (14.7) | ||
| 3 | 3408 (23.3) | 2973 (24.3) | ||
| 4 | 3887 (26.6) | 3526 (28.8) | ||
| 5 or more | 5317 (36.4) | 3934 (32.2) | 30.5 | <0.0001 |
| Occupation | ||||
| Professional | 2409 (16.5) | 1552 (12.7) | ||
| All other | 6194 (42.4) | 5341 (43.6) | ||
| Skilled labour | 2401 (16.4) | 2162 (17.7) | ||
| General labour | 3618 (24.7) | 3187 (26.0) | 36.8 | <0.0001 |
Missing data on household income in 219 controls and 196 cases, and on possessions for 7 controls and 14 cases.