Definition of primary and secondary variables
| Variable | Units or category labels | Definition |
|---|---|---|
| *Regular defined as at least several times weekly. | ||
| †Regular defined as at least daily. | ||
| Primary | ||
| Age | Years | Age at baseline test |
| Gender | Yes/no | Yes if male |
| Dominant sided ear | Yes/no | Yes if ear is same side as dominant hand |
| Family history | Yes/no | If family member had unusual HL |
| Construction work | Years | Years of work in construction industry |
| Non-construction work | Years | Years of work in non-construction jobs with high noise exposure |
| Secondary | ||
| Race | Yes/no | Yes if Caucasian |
| Brown eyes | Yes/no | Yes if brown |
| Dark hair | Yes/no | Yes if black, brown, dark brown |
| Firearms, military | Years | Years of regular* military use of firearms or exposure to blasts/explosions |
| Firearms, non-military | Years | Years of regular* non-military firearm use |
| Machinery, military | Years | Years of regular† exposure to heavy machinery in the military |
| Machinery, non-military | Years | Years of regular† use of heavy machinery at home |
| Power tools | Hours/week | Average hours per week spent using power tools at home |
| Motorcycle use | Years | Years of regular* motorcycle riding |
| Other vehicles | Yes/no | Yes if regular* use of snowmobiles or piloting aircraft |
| Loud recreation | Yes/no | Yes if regular (at least several times monthly) attendance at concerts, dances, races, or sporting events |
| Loud music | Yes/no | Yes is listen to music at “loud” levels |
| Smoking status | Current, ex, never | Smoking status category at baseline test |
| Disease | Yes/no | Yes if any of the following were self reported: arthritis, kidney disease, meningitis, mumps, diabetes, autoimmune diseases, hypertension, high cholesterol, cardiovascular disease, scarlet fever, neurological or seizure disorders, otoschlerosis, or Meniere’s disease |
| Ear trauma | Yes/no | Yes if report of ear surgery (include P/E tube placement), or ear injury (including damage due to explosions or blasts) |
| Ototoxic therapy | Yes/no | Yes if history of intravenous antibiotic therapy within 6 months prior to test, chemotherapy within 6 months prior to test, antimalarials (quinine or chloroquine) within 48 hours prior to test or diuretics (Edecrin or Lasix) within one week prior to test |
| Aspirin | Yes/no | Yes if within 24 hours prior to test |
| Solvents | Years | Years of frequent exposure to solvents on or off the job |
| Paints | Years | Years of frequent exposure to oil based paints on or off the job |