Table 2.
Hazard ratios and 95% confidence intervals for incident gout according to various reproductive factors
| Subjects (n) | Events (n) |
Follow-up duration (PYs) | Incidence rate (per 1000 PYs) | Hazard ratio (95% confidence interval) | |||
|---|---|---|---|---|---|---|---|
| Model 1 | Model 2 | Model 3 | |||||
| Age at menarche (years) | |||||||
| ≤ 12 | 11,847 | 635 | 96,616 | 6.57 | 1 (Ref.) | 1 (Ref.) | |
| 13–14 | 146,020 | 8329 | 1,188,213 | 7.01 | 1.07 (0.98–1.16) | 1.06 (0.98–1.15) | |
| 15–16 | 430,498 | 24,984 | 3,505,757 | 7.13 | 1.08 (1.00–1.17) | 1.07 (0.99–1.16) | |
| > 16 | 488,013 | 30,104 | 3,975,279 | 7.57 | 1.15 (1.06–1.24) | 1.10 (1.02–1.19) | |
| Age at menopause (years) | |||||||
| < 40 | 15,754 | 1091 | 127,654 | 8.55 | 1.19 (1.12–1.26) | 1.12 (1.06–1.19) | |
| 40–44 | 53,742 | 3412 | 436,253 | 7.82 | 1.09 (1.05–1.13) | 1.06 (1.02–1.10) | |
| 45–49 | 290,992 | 17,389 | 2,371,231 | 7.33 | 1.02 (1.00–1.04) | 1.03 (1.01–1.04) | |
| 50–54 | 597,465 | 34,968 | 4,867,834 | 7.18 | 1 (Ref.) | 1 (Ref.) | |
| ≥ 55 | 118,425 | 7192 | 962,894 | 7.47 | 1.04 (1.01–1.07) | 0.97 (0.94–0.99) | |
| Reproductive span (years) | |||||||
| < 30 | 129,369 | 8259 | 1,051,444 | 7.85 | 1.06 (1.02–1.10) | 1.10 (1.06–1.14) | |
| 30–34 | 435,768 | 26,066 | 3,551,041 | 7.34 | 0.98 (0.96–1.02) | 1.06 (1.02–1.09) | |
| 35–39 | 439,093 | 25,375 | 3,577,359 | 7.09 | 0.95 (0.92–0.99) | 1.02 (0.99–1.05) | |
| ≥ 40 | 72,148 | 4352 | 586,022 | 7.43 | 1 (Ref.) | 1 (Ref.) | |
| Oral contraceptives (years) | |||||||
| Never | 895,102 | 52,498 | 7,292,924 | 7.20 | 1 (Ref.) | 1 (Ref.) | 1 (Ref.) |
| < 1 | 110,098 | 6846 | 895,403 | 7.65 | 1.06 (1.04–1.09) | 1.03 (1.00–1.06) | 1.03 (1.01–1.06) |
| ≥ 1 | 71,178 | 4708 | 577,539 | 8.15 | 1.13 (1.10–1.17) | 1.05 (1.02–1.08) | 1.05 (1.02–1.08) |
| Hormone replacement therapy (years) | |||||||
| Never | 877,088 | 51,071 | 7,142,979 | 7.15 | 1 (Ref.) | 1 (Ref.) | 1 (Ref.) |
| < 2 | 116,184 | 7508 | 946,434 | 7.93 | 1.11 (1.08–1.14) | 1.16 (1.13–1.18) | 1.16 (1.13–1.18) |
| 2–5 | 47,584 | 3075 | 387,867 | 7.93 | 1.11 (1.07–1.15) | 1.16 (1.12–1.21) | 1.16 (1.12–1.21) |
| ≥ 5 | 35,522 | 2398 | 288,586 | 8.31 | 1.16 (1.12–1.21) | 1.19 (1.14–1.23) | 1.18 (1.14–1.23) |
| Parity | |||||||
| 0 children | 28,422 | 1700 | 230,168 | 7.39 | 1 (Ref.) | 1 (Ref.) | 1 (Ref.) |
| 1 child | 73,227 | 4210 | 595,161 | 7.07 | 0.96 (0.91–1.01) | 1.00 (0.94–1.06) | 1.00 (0.94–1.06) |
| ≥ 2 children | 974,729 | 58,142 | 7,940,536 | 7.32 | 0.99 (0.94–1.04) | 0.99 (0.94–1.05) | 0.99 (0.94–1.05) |
| Breastfeeding (months) | |||||||
| Never | 79,504 | 4619 | 644,896 | 7.16 | 1 (Ref.) | 1 (Ref.) | 1 (Ref.) |
| < 6 | 78,178 | 4070 | 637,261 | 6.39 | 0.89 (0.85–0.93) | 0.93 (0.89–0.98) | 0.93 (0.89–0.97) |
| 6–12 | 199,070 | 11,213 | 1,621,738 | 6.91 | 0.96 (0.93–1.00) | 0.98 (0.94–1.01) | 0.98 (0.94–1.01) |
| ≥ 12 | 719,626 | 44,150 | 5,861,970 | 7.53 | 1.05 (1.02–1.08) | 1.00 (0.96–1.03) | 1.00 (0.96–1.03) |
PYs person-years, Ref. reference group
Model 1: crude model
Model 2: multivariable model including age, age at menarche, age at menopause, oral contraceptives, hormone replacement therapy, parity, breastfeeding, body mass index, smoking, alcohol consumption, regular exercise, hypertension, diabetes mellitus, hyperlipidemia, chronic kidney disease, and income
Model 3: multivariable model including variables of Model 2 except for age at menarche and age at menopause replaced by reproductive span