Table 1.
Descriptive Characteristics of the Study Population, Incidence of New-Onset Asthma, and Adjusted Relative Risk of Self-Reported New-Onset Asthma According to Sex, Millennium Cohort Study, United States, 2001–2013
| Characteristic | Mena,b (n = 52,826) | Womena,c (n = 22,944) | ||||||
|---|---|---|---|---|---|---|---|---|
| No. | New-Onset Asthma, % | RR | 95% CI | No. | New-Onset Asthma, % | RR | 95% CI | |
| Exposure of interest | ||||||||
| Combat deployment during follow-upd | ||||||||
| Not deployed | 29,237 | 3.1 | 1.00 | Referent | 15,678 | 5.0 | 1.00 | Referent |
| Deployed without combat experience | 8,922 | 1.6 | 0.97 | 0.83, 1.15 | 3,577 | 3.0 | 0.97 | 0.80, 1.18 |
| Deployed with combat experience | 14,667 | 2.7 | 1.30 | 1.14, 1.47 | 3,689 | 4.4 | 1.24 | 1.05, 1.46 |
| Demographic factors | ||||||||
| Race/ethnicity | ||||||||
| White, non-Hispanic | 41,880 | 2.7 | 1.00 | Referent | 15,895 | 4.4 | 1.00 | Referent |
| Black, non-Hispanic | 4,484 | 3.1 | 1.01 | 0.85, 1.20 | 3,692 | 5.1 | 1.06 | 0.90, 1.24 |
| Asian/Pacific Islander | 1,899 | 2.1 | 0.91 | 0.67, 1.22 | 1,051 | 4.6 | 1.44 | 1.12, 1.86 |
| Hispanic | 3,414 | 3.7 | 1.28 | 1.08, 1.53 | 1,701 | 5.5 | 1.37 | 1.13, 1.66 |
| Other | 1,149 | 2.5 | 0.84 | 0.59, 1.20 | 605 | 5.1 | 1.15 | 0.82, 1.61 |
| Birth year | ||||||||
| 1980 or later | 14,454 | 2.0 | 1.00 | Referent | 9,435 | 3.4 | 1.00 | Referent |
| 1970–1979 | 15,078 | 2.8 | 0.94 | 0.78, 1.14 | 6,754 | 5.0 | 1.14 | 0.96, 1.36 |
| Before 1970 | 23,294 | 3.2 | 0.96 | 0.77, 1.21 | 6,755 | 5.9 | 1.19 | 0.96, 1.48 |
| Marital status | ||||||||
| Never married | 14,362 | 2.1 | 0.88 | 0.77, 1.01 | 9,257 | 4.4 | 1.13 | 0.99, 1.30 |
| Married | 34,164 | 3.0 | 1.00 | Referent | 9,841 | 4.3 | 1.00 | Referent |
| Divorced/widowed/separated | 4,300 | 3.2 | 0.89 | 0.75, 1.05 | 3,846 | 6.0 | 1.19 | 1.02, 1.38 |
| Education | ||||||||
| High school degree/GED or less | 9,686 | 2.5 | 0.95 | 0.79, 1.15 | 3,296 | 4.1 | 0.9 | 0.71, 1.14 |
| Some college or associate degree | 26,452 | 3.0 | 1.02 | 0.88, 1.19 | 12,142 | 4.9 | 1.13 | 0.95, 1.34 |
| Bachelor degree or higher | 16,688 | 2.5 | 1.00 | Referent | 7,506 | 4.3 | 1.00 | Referent |
| BMIe,f | ||||||||
| Underweight/normal (<25.0) | 14,872 | 2.2 | 1.00 | Referent | 13,182 | 4.1 | 1.00 | Referent |
| Overweight (25.0–29.9) | 28,516 | 2.8 | 1.30 | 1.14, 1.47 | 7,498 | 5.2 | 1.36 | 1.20, 1.53 |
| Obese (≥30.0) | 9,438 | 3.4 | 1.88 | 1.62, 2.18 | 2,264 | 5.6 | 1.68 | 1.42, 2.00 |
| Enrollment panelg | ||||||||
| 2001–2003 | 32,852 | 3.2 | 1.00 | Referent | 10,878 | 5.8 | 1.00 | Referent |
| 2004–2006 | 8,016 | 2.6 | 0.97 | 0.81, 1.16 | 5,024 | 4.3 | 1.01 | 0.85, 1.20 |
| 2007–2008 | 11,958 | 1.7 | 0.74 | 0.59, 0.92 | 7,042 | 2.9 | 0.76 | 0.62, 0.95 |
| Military service | ||||||||
| Service branch | ||||||||
| Army | 23,206 | 3.5 | 1.00 | Referent | 10,464 | 5.5 | 1.00 | Referent |
| Navy/Coast Guard | 9,354 | 2.4 | 0.79 | 0.69, 0.91 | 4,309 | 4.4 | 0.96 | 0.82, 1.12 |
| Marine Corps | 4,877 | 2.0 | 0.68 | 0.55, 0.84 | 676 | 4.4 | 0.98 | 0.70, 1.39 |
| Air Force | 15,389 | 2.1 | 0.69 | 0.61, 0.79 | 7,495 | 3.5 | 0.79 | 0.69, 0.91 |
| Service component | ||||||||
| Active duty | 32,986 | 2.7 | 1.00 | Referent | 13,354 | 4.5 | 1.00 | Referent |
| Reserve/Guard | 19,840 | 2.8 | 0.83 | 0.74, 0.93 | 9,590 | 4.8 | 0.93 | 0.82, 1.05 |
| Occupation | ||||||||
| Infantry, gun crews, seamen (combat specialist) | 12,285 | 2.5 | 1.00 | Referent | 1,429 | 3.4 | 1.00 | Referent |
| Electrical repair | 5,703 | 2.4 | 1.11 | 0.92, 1.34 | 1,512 | 3.3 | 0.93 | 0.65, 1.33 |
| Communication/intelligence | 4,263 | 3.1 | 1.17 | 0.96, 1.43 | 1,951 | 5.4 | 1.56 | 1.14, 2.15 |
| Health care | 3,745 | 3.2 | 1.26 | 1.03, 1.55 | 5,002 | 4.8 | 1.41 | 1.05, 1.88 |
| Other technical and specialty | 1,475 | 3.3 | 1.54 | 1.18, 2.03 | 698 | 4.7 | 1.51 | 1.01, 2.25 |
| Functional support | 7,403 | 3.1 | 1.34 | 1.14, 1.58 | 6,664 | 4.7 | 1.21 | 0.91, 1.62 |
| Electrical/mechanical equipment repair | 9,041 | 2.7 | 1.17 | 0.99, 1.38 | 1,734 | 3.8 | 1.00 | 0.70, 1.42 |
| Craft workers | 1,878 | 2.7 | 1.26 | 0.96, 1.65 | 422 | 4.0 | 0.97 | 0.58, 1.62 |
| Service and supply | 4,503 | 3.2 | 1.30 | 1.08, 1.57 | 2,318 | 5.7 | 1.32 | 0.96, 1.81 |
| Non-occupation | 2,530 | 1.7 | 0.85 | 0.63, 1.16 | 1,214 | 4.5 | 1.63 | 1.14, 2.32 |
| Pay grade | ||||||||
| Enlisted | 40,620 | 2.9 | 1.25 | 1.05, 1.49 | 17,984 | 4.8 | 1.14 | 0.93, 1.39 |
| Officerh | 12,206 | 2.3 | 1.00 | Referent | 4,960 | 4.0 | 1.00 | Referent |
| Military service statusf | ||||||||
| Currently serving | 44,404 | 2.9 | 1.00 | Referent | 19,450 | 4.6 | 1.00 | Referent |
| Former service member | 8,422 | 1.9 | 1.00 | 0.87, 1.16 | 3,494 | 4.4 | 1.37 | 1.17, 1.59 |
| Prior deploymenti | ||||||||
| Yes | 12,082 | 3.0 | 0.96 | 0.84, 1.09 | 1,429 | 5.6 | 0.98 | 0.79, 1.21 |
| No | 40,744 | 2.7 | 1.00 | Referent | 21,515 | 4.5 | 1.00 | Referent |
| Behavioral factors | ||||||||
| Smoking statusf | ||||||||
| Nonsmoker | 30,367 | 2.7 | 1.00 | Referent | 14,553 | 4.3 | 1.00 | Referent |
| Former smoker | 13,540 | 2.8 | 0.93 | 0.83, 1.05 | 5,163 | 5.0 | 1.11 | 0.97, 1.27 |
| Current smoker | 8,919 | 2.9 | 1.01 | 0.88, 1.16 | 3,228 | 5.3 | 1.09 | 0.92, 1.28 |
| Environmental exposures | ||||||||
| Occupational hazards requiring protective equipmentf | ||||||||
| Yes | 27,680 | 3.0 | 0.97 | 0.86, 1.09 | 7,358 | 5.4 | 1.13 | 0.99, 1.29 |
| No | 24,104 | 2.5 | 1.00 | Referent | 15,139 | 4.2 | 1.00 | Referent |
| Don’t know | 1,042 | 3.4 | 1.09 | 0.80, 1.50 | 447 | 5.6 | 1.11 | 0.76, 1.63 |
| Routine skin contact with paints/solvents/substancesf | ||||||||
| Yes | 13,011 | 3.4 | 1.11 | 0.98, 1.26 | 2,881 | 5.7 | 1.00 | 0.84, 1.19 |
| No | 37,463 | 2.5 | 1.00 | Referent | 19,271 | 4.4 | 1.00 | Referent |
| Don’t know | 2,352 | 3.7 | 1.17 | 0.93, 1.47 | 792 | 5.1 | 0.93) | 0.68, 1.27 |
| Pesticides, including creams, sprays, and uniform treatments, and applied in the environment/surroundingsf | ||||||||
| Yes | 19,133 | 3.2 | 1.08 | 0.96, 1.21 | 6,238 | 5.7 | 1.18 | 1.03, 1.35 |
| No | 29,579 | 2.4 | 1.00 | Referent | 14,732 | 4.1 | 1.00 | Referent |
| Don’t know | 4,114 | 3.2 | 1.01 | 0.84, 1.21 | 1,974 | 5.0 | 0.99 | 0.80, 1.21 |
| Stressors | ||||||||
| Life stressor eventsf,j | ||||||||
| None | 40,568 | 2.2 | 1.00 | Referent | 14,243 | 3.5 | 1.00 | Referent |
| 1 event | 9,401 | 4.2 | 1.31 | 1.16, 1.47 | 5,231 | 5.4 | 1.11 | 0.97, 1.27 |
| >1 event | 2,857 | 5.6 | 1.37 | 1.15, 1.62 | 3,470 | 8.0 | 1.31 | 1.12, 1.52 |
| PTSDf,k | ||||||||
| Yes | 2,840 | 4.8 | 1.82 | 1.55, 2.15 | 1,506 | 7.8 | 1.56 | 1.30, 1.88 |
| No | 49,986 | 2.6 | 1.00 | Referent | 21,438 | 4.4 | 1.00 | Referent |
Abbreviations: BMI, body mass index; CI, confidence interval; GED, General Educational Development certificate; PTSD, posttraumatic stress disorder; RR, relative risk.
a Univariate analyses were performed separately for men and women. For both sexes, combat deployment, birth year, marital status, education, BMI, enrollment panel, service branch, occupation, pay grade, environmental exposures, life stressor events, and PTSD were significantly associated with new-onset asthma (α = 0.05). Models were fitted separately for men and women; both models adjusted for all variables in the table.
b Among men, race/ethnicity and military service status were also significantly associated with new-onset asthma (α = 0.05).
c Among women, smoking status was also significantly associated with new-onset asthma (α = 0.05).
d Deployment was defined as being deployed in support of Operation Enduring Freedom or Operation Iraqi Freedom. Combat was defined as reporting personal exposure to ≥1 of the following: witnessing death, witnessing physical abuse, dead and/or decomposing bodies, maimed soldiers or civilians, or prisoners of war or refugees. Combat deployment was assessed over the entire follow-up period.
e BMI was calculated as weight (kg) divided by height (m) squared.
f Time-varying covariates were measured at the survey prior to the final survey (the survey at which new-onset asthma was reported or the last survey completed, whichever came first).
g This study used 3 panels of Millennium Cohort Study participants. Participants completed their baseline survey during the listed years (Panel 1: 2001–2003, Panel 2: 2004–2006, Panel 3: 2007–2008).
h Officer includes commissioned and warrant officers.
i Prior deployments to Bosnia, Kosovo, or Southwest Asia between January 1, 1998, and September 1, 2001.
j Categorized number of endorsements of the following events: divorce or separation, financial problems, sexual assault, sexual harassment, physical assault, or suffered a disabling illness or injury.
k Based on the PTSD Checklist–Civilian Version, using sensitive diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition.