Table 3. Incidence of ankylosing spondylitis (AS) according to hs-CRP concentration, with stratification by sex and age.
| Plasma concentrations of hs-CRP (mg/L) | P for trend | P for interaction | ||||
|---|---|---|---|---|---|---|
| <1.00 | 1.00–2.99 | 3.00–9.99 | ≥10.0 | |||
| Sex | 0.39 | |||||
| Male | ||||||
| n | 50,750 | 27,623 | 16,384 | 4,147 | ||
| Incidence of AS | 11 | 8 | 15 | 17 | ||
| Incidence ratea | 0.03 | 0.04 | 0.11 | 0.50 | ||
| HR (95% CI) | 1.00 | 1.62 (0.65–4.06) | 5.6 (2.5–12.4) | 24.9 (11.5–54.1) | <0.001 | |
| Female | ||||||
| n | 12,671 | 6,620 | 4,443 | 1,015 | ||
| Incidence of AS | 3 | 0 | 1 | 0 | ||
| Incidence ratea | 0.03 | 0.00 | 0.03 | 0.00 | ||
| HR (95% CI) | 1.00 | — | 1.4 (0.1–14.0) | — | 0.88 | |
| Age | 0.23 | |||||
| <45 years | ||||||
| n | 24,434 | 11,711 | 5,090 | 1,167 | ||
| Incidence of AS | 8 | 1 | 5 | 6 | ||
| Incidence ratea | 0.04 | 0.01 | 0.14 | 0.71 | ||
| HR (95% CI) | 1.00 | 0.31 (0.04–2.46) | 3.7 (1.2–11.5) | 18.1 (6.1–53.4) | <0.001 | |
| ≥45 years | ||||||
| n | 41,794 | 24,634 | 16,647 | 4,204 | ||
| Incidence of AS | 6 | 7 | 11 | 11 | ||
| Incidence ratea | 0.02 | 0.04 | 0.08 | 0.32 | ||
| HR (95% CI) | 1.00 | 2.35 (0.79–7.05) | 5.5 (2.0–15.2) | 20.6 (7.5–56.4) | <0.001 | |
HR, hazard ratio; CI, confidence interval; hs-CRP, high-sensitivity C-reactive protein. The model was adjusted for age, sex, education, average monthly income of each family member, smoking, alcohol intake, physical activity, body mass index, blood-pressure status, blood glucose status, total cholesterol, history of cardiovascular disease, and use of antihypertensives, lipid-lowering agents, and aspirin.
aIncidence rate per 1,000 person-years.