Scientific Collaboration

Questionnaires & Study Data

The AHS cohort includes 89,656 private pesticide applicators, spouses of private applicators, and commercial pesticide applicators recruited in Iowa and North Carolina (Table 1). Participants were recruited from 1993 to 1997. Follow-up telephone interviews were conducted in 1999-2003 (Phase 2), 2005-2010 (Phase 3) and 2013-2015 (Phase 4). The Phase 2 interview was completed by 64% of private applicators, 59% of commercial applicators, and 74% of spouses. Participants provided updated information on farming practices, lifestyle, and health and were asked to complete a dietary questionnaire and provide a sample of cheek cells as a source of DNA. The Phase 3 and Phase 4 interviews also updated information on farming practices, lifestyle, and health. Phase 3 was completed by 60% of enrolled private applicators and 66% of enrolled spouses. Phase 4 was completed by follow up 61% of the enrolled private applicators and 61% of enrolled spouses.  

Questionnaires Used in the AHS

Phase 1

Phase 2

Phase 3

Phase 4

Phase 1 (1993-1997) Questionnaires
Self-administered questionnaires obtained information on lifetime pesticide use, and demographic and medical history information.

Applicators were asked to complete two questionnaires—one that was filled out at a pesticide training/licensing location and one to be filled out at home and mailed back. While over 80% of licensed applicators enrolled in the study by completing the on-site form, only 44% returned the second questionnaire. Although the content was similar with respect to exposures, the second questionnaire obtained more detailed information one some pesticides, as well as some details of medical history and information on some covariates (e.g., BMI).

Private applicators were also given questionnaires to be filled out by their spouse, and 75% of married spouses completed them to enroll. Women who enrolled (both spouses and female applicators) were asked to complete a Female and Family Health questionnaire that obtained reproductive histories and information about children; 60% of female participants completed it.

Phase 2 (1999-2003) and Phase 3 (2005-2010) Follow-up Questionnaires
These phases involved computer-assisted telephone interviews to obtain information on current pesticide use, potential confounders, and medical history.

In Phase 2, exposure questions were similar for applicators and spouses, and the health questionnaires varied slightly by gender and age. In addition, participants who completed the follow-up survey were asked to complete a self-completed food frequency questionnaire (the NCI Diet History Questionnaire, with added items on cooking practices). About 40% of the cohort completed the diet questionnaire.

In Phase 3, a common instrument was used for better integration of data for applicators and spouses.

Phase 4 (2013-2015) Follow-Up Questionnaire
This follow-up focuses on health changes and updating important covariates such as smoking and family history of disease. We invited approximately 70,000 Phase 3 eligible subjects to participate regardless of whether they participated in the Phase 3 interview. For the first time, in order to recover crucial data on their health histories, we also interviewed the next-of-kin for participants who were incapacitated or deceased. The data collection was done primarily via mailed questionnaires, supplemented by computer assisted telephone interviews with those who did not respond to the mailings. Approximately 61% of eligible AHS participants or their proxies completed the Phase 4 survey. This Phase 4 data collection will greatly facilitate research on non-cancer chronic diseases, including diseases of aging, for which there are no registries.

Table 1: AHS Cohort-wide Data Collection and Response Rates

  Phase 1
Phase 2
Phase 3
Phase 4
  Enrolled Main Questionnaire Buccal cells* Diet History Questionnaire* Main Questionnaire Main Questionnaire
  N N (%) N (%) N (%) N (%) N (%)
Private Applicators 52,395 33,457 69 18,568 38 17,969 37 24,171 60 23,988 61
Spouses 32,347 23,796 76 14,407 46 15,445 49 19,959 66 18,064 61
Commercial Applicators 4,916 2,885 59 1,835 38 1,750 36 NA NA NA NA
Total 89,658 60,138   34,810   35,164   42,052   44,130