Characteristics of study participants according to symptom pattern
| Characteristic | Asymptomatic | Resolved LRS | Persistent LRS |
| n=321 | n=110 | n=55 | |
| %* | %* | %* | |
| Female sex | 52.3 | 62.7 | 78.2 |
| Age on 9/11 (years) | |||
| <25 | 10.0 | 2.7 | 1.8 |
| 25–44 | 54.8 | 58.2 | 50.9 |
| 45–64 | 34.0 | 36.4 | 45.5 |
| 65+ | 1.3 | 2.7 | 1.8 |
| Race/ethnicity | |||
| non-Hispanic white | 76.0 | 58.2 | 38.2 |
| Non-Hispanic black | 6.2 | 19.1 | 16.4 |
| Hispanic | 4.4 | 10.0 | 27.3 |
| Asian | 11.5 | 10.0 | 7.3 |
| Multiracial and other races | 1.9 | 2.7 | 10.9 |
| Education: college or higher | 85.7 | 74.6 | 50.9 |
| BMI at exam 1 | |||
| normal/low (<25) | 57.3 | 33.6 | 21.8 |
| Overweight (25–29.9) | 28.0 | 31.8 | 40.0 |
| Obese (≥30) | 13.7 | 34.6 | 38.2 |
| Dust cloud exposure on 9/11 | |||
| No | 64.2 | 32.7 | 23.6 |
| Yes | 31.5 | 64.6 | 65.5 |
| PTSD (assessed 2006–2007) | 2.5 | 29.1 | 43.6 |
p Value for χ2 comparing patterns across three main symptom groups <0.001 for all characteristics shown except age (p=0.07).
*Percentages may not sum up to 100 due to missing data.
†Defined as a PTSD checklist score ≥44 on the 2006–2007 Registry questionnaire.
BMI, body mass index; LRS, lower respiratory symptoms; PTSD, post-traumatic stress disorder.