Author Contributions: Dr Ottenbacher had full
access to all of the data in the study and takes responsibility for the integrity
of the data and the accuracy of the data analysis.
Study concept and design: Ottenbacher, Granger.
Acquisition of data: Illig, Smith, Linn.
Analysis and interpretation of data: Ottenbacher,
Drafting of the manuscript: Ottenbacher, Ostir,
Critical revision of the manuscript for important
intellectual content: Illig, Smith, Granger.
Statistical analysis: Ottenbacher, Ostir.
Obtained funding: Ottenbacher.
Administrative, technical, or material support:
Illig, Smith, Granger.
Study supervision: Ottenbacher, Linn.
Funding/Support: This research was supported
by National Institutes of Health grants R01 HD34622 and KO2 AG019736 (Dr Ottenbacher).
Role of the Sponsor: The funding agency did
not have any direct influence on the design or conduct of the study; the collection,
analyses, or interpretation of the data; or the preparation, review, or approval
of the manuscript.