Table 3. Pooled HRs Between Multivitamin Use and Mortality .
| Cause of death | Follow-up period 1a | Follow-up period 2a | P value | |||
|---|---|---|---|---|---|---|
| Nondaily use | Daily use | Nondaily use | Daily use | |||
| All-cause mortality | ||||||
| Deaths, No. | 4505 | 17 843 | 13 822 | 52 834 | NA | |
| Age and sex-adjusted HR (95% CI) | 1.06 (1.02-1.09) | 0.99 (0.97-1.01) | 0.92 (0.86-0.99) | 0.99 (0.95-1.04) | <.001 | |
| Multivariable-adjusted HR (95% CI)b | 1.09 (1.05-1.13) | 1.04 (1.02-1.07) | 0.95 (0.88-1.02) | 1.04 (0.99-1.08) | <.001 | |
| Heart disease mortality | ||||||
| Deaths, No. | 789 | 3422 | 2930 | 11 609 | NA | |
| Age and sex-adjusted HR (95% CI) | 0.99 (0.91-1.07) | 1.00 (0.95-1.05) | 0.90 (0.77-1.06) | 1.00 (0.90-1.10) | .95 | |
| Multivariable-adjusted HR (95% CI)b | 1.03 (0.95-1.11) | 1.06 (1.01-1.11) | 0.93 (0.79-1.10) | 1.04 (0.94-1.15) | .06 | |
| Cancer mortality | ||||||
| Deaths, No. | 1937 | 7426 | 3748 | 13 221 | NA | |
| Age and sex-adjusted HR (95% CI) | 1.02 (0.97-1.07) | 0.96 (0.93-0.99) | 0.90 (0.81-1.01) | 0.94 (0.87-1.01) | .004 | |
| Multivariable-adjusted HR (95% CI)b | 1.05 (1.00-1.10) | 1.01 (0.98-1.05) | 0.93 (0.84-1.04) | 0.98 (0.91-1.06) | .20 | |
| Cerebrovascular diseases mortality | ||||||
| Deaths, No. | 186 | 808 | 839 | 3370 | NA | |
| Age and sex-adjusted HR (95% CI) | 1.06 (0.90-1.24) | 1.05 (0.95-1.16) | 0.97 (0.70-1.36) | 1.07 (0.87-1.31) | .58 | |
| Multivariable-adjusted HR (95% CI)b | 1.04 (0.89-1.23) | 1.05 (0.95-1.16) | 0.97 (0.69-1.36) | 1.06 (0.86-1.31) | .66 | |
Abbreviations: HR, hazard ratio; NA, not applicable.
The proportional hazards assumption was violated (P < .001). Therefore, follow-up time was stratified by the midpoint, and HRs were calculated using an interaction term between follow-up period and the exposure variable. Follow-up period 1 was the first 12 years of follow-up and follow-up period 2 was the last 15 years of follow-up.
Models were adjusted sex (male or female), age at enrollment (years), race and ethnicity (American Indian or Alaska Native, Asian or Pacific Islander, Hispanic, non-Hispanic Black, or non-Hispanic White), education (≤11 years; 12 years, completed high school or General Educational Development; post–high school training; some college; college and postgraduate; or other), body mass index (calculated as weight in kilograms divided by height in meters squared) category (<18.5, 18.5 to <25, 25 to <30, ≥30), marital status (married or living as married, divorced or separated, widowed, or never married), smoking status (never smoker, former smoker, current smoker ≤20 cigarettes/d, current smoker 21-40 cigarettes/d, or current smoker >40 cigarettes/d), alcohol consumption (0 drinks per day, <1 drink/d, 1 to <2 drinks/d, 2 to <3 drinks/d, ≥3 drinks/d), physical activity level (never, low, moderate, high), coffee intake (0 cups/d, <1 cup/d, 1 cup/d, 2-3 cups/d, 4-5 cups/d, or ≥6 cups/d), family history of cancer (yes or no), Healthy Eating Index 2015 quartile (quartile 1, 21.55 to <60.90; quartile 2, 60.90 to <68.00; quartile 3, 68:00 to <74.20; and quartile 4, 74.20 to <96.10), and use of individual supplements (yes or no). Detailed results for each cohort are presented in eTable 2 in Supplement 1.