Data quality from a longitudinal study of adolescent health at schools near industrial livestock facilities.
OBJECTIVE
Longitudinal designs enable examination of temporal relationships between exposures and health outcomes, but extended participation can cause study fatigue. We present an approach for analyzing data quality and study fatigue in a participatory, longitudinal study of adolescents.


METHODS
Participants (n = 340) in the Rural Air Pollutants and Children's Health study completed daily diaries for 3 to 5 weeks in 2009 while we monitored outdoor pollutant concentrations. We used regression models to examine established associations between disease, symptoms, anthropometrics, and lung function as indicators of internal consistency and external validity. We modeled temporal trends in data completeness, lung function, environmental odors, and symptoms to assess study fatigue.


RESULTS
Of 5728 records, 94.2% were complete. Asthma and allergy status were associated with asthma-related symptoms at baseline and during follow-up, for example, prevalence ratio = 8.77 (95% confidence interval: 4.33-17.80) for awakening with wheeze among diagnosed asthmatics versus nonasthmatics. Sex, height, and age predicted mean lung function. Plots depicting outcome reporting over time and associated linear trends showed time-dependent declines for most outcomes.


CONCLUSIONS
We achieved data completeness, internal consistency, and external validity, yet still observed study fatigue, despite efforts to maintain participant engagement. Future investigators should model time trends in reporting to monitor longitudinal data quality.
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill. Electronic address: virginia.guidry@unc.edu.
Virginia T
VT
Guidry
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill.
Christine L
CL
Gray
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill.
Amy
A
Lowman
Rural Empowerment Association for Community Help, Warsaw, NC.
Devon
D
Hall
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill.
Steve
S
Wing
D000293:Adolescent; D000067697:Adolescent Health; D000367:Age Factors; D000397:Air Pollution / Q000009:adverse effects*; D000822:Animal Husbandry; D000818:Animals; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D000068598:Data Accuracy; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D008137:Longitudinal Studies; D008297:Male; D011200:Poultry; D012129:Respiratory Function Tests; D012135:Respiratory Sounds; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D013552:Swine
Adolescents; Asthma; Community-based participatory research; Data quality; Environmental health; Livestock; Longitudinal studies; Wheezing