Factors associated with incidence of idiopathic pulmonary fibrosis (primary cohort)
| Incidence rate# (95% CI)¶ | Adjusted incidence rate ratio (95% CI) | |
| All enrolees | 6.1 (5.9–6.4) | |
| Age years+ | ||
| 18–34 | 1.1 (1.0–1.3) | 0.06§ (0.05–0.06) |
| 35–44 | 2.6 (2.4–2.9) | 0.15§ (0.14–0.16) |
| 45–54 | 6.4 (6.0–6.9) | 0.36§ (0.34–0.39) |
| 55–64 | 19.3 (18.4–20.3) | 1.00 (Reference) |
| Sex | ||
| Male | 6.4 (6.1–6.7) | 1.08 (1.02–1.15) |
| Female | 5.9 (5.6–6.2) | 1.00 (Reference) |
| Census region | ||
| New England | 5.4 (5.0–5.9) | 0.80§ (0.71–0.90) |
| Middle Atlantic | 6.3 (5.7–6.9) | 1.00 (0.89–1.12) |
| South Atlantic | 7.9 (7.3–8.5) | 1.22§ (1.09–1.37) |
| East South Central | 8.2 (6.7–9.8) | 1.07 (0.88–1.30) |
| West South Central | 6.1 (5.5–6.7) | 1.22§ (1.08–1.37) |
| East North Central | 6.6 (5.9–7.3) | 1.00 (Reference) |
| West North Central | 4.5 (3.8–5.2) | 0.74§ (0.63–0.87) |
| Mountain | 5.4 (4.6–6.2) | 0.79§ (0.68–0.93) |
| Pacific | 4.0 (3.2–4.9) | 0.91 (0.76–1.09) |
| Other/unknown | 9.1 (2.8–25.2) | 1.72 (0.64–4.61) |
#: incidence rate reported as number of new cases per 100 000 person-years using data from 2005 to 2010; ¶: estimated based on Poisson distribution; +: age at entry into the database; §: statistically significant at p<0.05.