Table 3.
Categorisation of working hours of 195 Japanese men with acute myocardial infarction and 331 controls matched for age and occupation, and odds ratios for infarction in relation to working hours
| No (%) of subjects
|
Odds ratio (95% CI)
|
||||
|---|---|---|---|---|---|
| Mean daily working hours | Cases (n=195) | Controls (n=331) | Crude* | Multiple logistic† | |
| In last month before infarction | |||||
| ⩽7.00 | 45 (23) | 32 (10) | 3.07 (1.77 to 5.32) | 2.83 (1.52 to 5.28) | |
| 7.01-9.00 | 80 (41) | 182 (55) | 1.00 | 1.00 | |
| 9.01-11.00 | 46 (24) | 96 (29) | 1.06 (0.68 to 1.67) | 0.96 (0.58 to 1.60) | |
| ⩾11.01 | 24 (12) | 21 (6) | 2.44 (1.26 to 4.73) | 2.94 (1.39 to 6.25) | |
| In month with shortest mean working hours | |||||
| ⩽6.00 | 46 (24) | 31 (9) | 2.71 (1.60 to 4.60) | 2.59 (1.44 to 4.69) | |
| 6.01-8.00 | 96 (49) | 195 (59) | 1.00 | 1.00 | |
| 8.01-9.00 | 32 (16) | 59 (18) | 1.08 (0.65 to 1.81) | 1.03 (0.59 to 1.83) | |
| ⩾9.01 | 21 (11) | 46 (14) | 0.89 (0.49 to 1.61) | 0.93 (0.48 to 1.78) | |
| Increase from month with shortest hours to month before infarction | |||||
| ⩽1.00 | 121 (62) | 244 (74) | 1.00 | 1.00 | |
| 1.01-2.00 | 30 (15) | 50 (15) | 1.28 (0.77 to 2.13) | 1.33 (0.75 to 2.37) | |
| 2.01-3.00 | 18 (9) | 17 (5) | 2.24 (1.11 to 4.55) | 2.38 (1.08 to 5.26) | |
| ⩾3.01 | 26 (13) | 20 (6) | 2.53 (1.34 to 4.77) | 2.49 (1.24 to 4.99) | |
*
Adjusted for age and occupation categories classified in 1990 Japanese census.
†
Adjusted for age, occupation category, hypertension, hypercholesterolaemia, diabetes, body mass index, smoking habits, proportion of sedentary work, and burnout index.