ME and JR designed the questionnaires, coordinated trial field-work, acquisition of data and follow-up.
RG had the idea for the study, designed the study, obtained the funding, developed the questionnaires, coordinated the study, and wrote the paper.
RG had the idea for the study, obtained the funding, designed the study, developed the questionnaires, coordinated the study, and wrote the paper.
M.B. contributed to the design of the study and the questionnaires, coordinated the data collection, contributed to the data analysis, interpretation of the data and wrote the first draft of the paper.
TMH developed the county questionnaire, coordinated data collection and established the cohort, EA contributed significantly to the statistical analysis and drafting of the paper.
PF wrote the protocol and questionnaire, coordinated both studies and wrote the initial manuscript.
EE and ML conceived of and designed the study, designed the draft questionnaires, coordinated the study and drafted the manuscript.
IB participated in the design of the questionnaire and coordinated the study.
CYC and TCL participated in the design of the study, designed the questionnaire and coordinated the training for telephone interview.
ARV assisted in design of the questionnaire and coordinated data collection and supervised collection of blood samples.
