Recall bias in a prospective cohort study of acute time-varying exposures: Example from the herpetic eye disease study

Kip, Kevin E; Cohen, Frances; Cole, Stephen R; Wilhelmus, Kirk R; Patrick, Donald L; Blair, R.Clifford; Beck, Roy W; for the Herpetic Eye Disease Study Group,

« Previous Next »Journal of Clinical Epidemiology
Volume 54, Issue 5 , Pages 482-487, May 2001

Recall bias in a prospective cohort study of acute time-varying exposures:

Example from the herpetic eye disease study

Kevin E Kip
- University of South Florida, Florida Mental Health Institute, Department of Mental Health Law and Policy, 13301 Bruce B. Downs, Blvd., Tampa FL, 33612-3807, USA
- Jaeb Center for Health Research, Tampa, FL, USA
- Corresponding author. Tel.: 813-974-7873; fax: 813-974-9327.(K.E. Kip)
Frances Cohen
- Health Psychology Program, University of California, San Francisco, CA, USA
Stephen R Cole
- Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
Kirk R Wilhelmus
- Cullen Eye Institute, Baylor College of Medicine, Houston, TX, USA
Donald L Patrick
- University of Washington, Department of Health Services, Seattle, WA, USA
R.Clifford Blair
- University of South Florida, Department of Epidemiology and Biostatistics, Tampa, FL, USA
Roy W Beck
- Jaeb Center for Health Research, Tampa, FL, USA
for the Herpetic Eye Disease Study Group

Received 22 February 2000; received in revised form 30 June 2000; accepted 2 August 2000.

Abstract

Recall bias is possible in a prospective cohort study when exposure status is transient and must be periodically recalled, and ascertainment occurs after symptom onset. We know of no published demonstration of such bias at play in a prospective cohort study. In a substudy of a randomized clinical trial, 308 participants were prospectively followed to investigate potential acute triggers of ocular herpes simplex virus (HSV) recurrences. Participants reported on the presence of systemic infection or high psychological stress (exposures) on a home log that was completed weekly for up to 15 months and mailed to the study's coordinating centers. By protocol, exposure reporting was to occur on the last day of the week (Sunday) so that a prospective 1-week lag period between exposure and outcome in the following week could be assessed. The study outcome was development of a recurrence of ocular HSV disease documented by clinical examination. Using 35 weekly reports of exposure properly completed before the week of an outcome, there was no evidence of higher risk of HSV recurrence associated with systemic infection (rate ratio = 0.62, 95% confidence interval [CI]: 0.19–2.02) or high psychological stress rate (ratio = 0.0, 95% CI: 0.0–undefined). In contrast, when the analysis was based on 26 weekly reports of exposure improperly completed on or after the date of outcome, the risk of recurrence associated with systemic infection was estimated to be 4-fold (rate ratio = 4.07, 95% CI: 1.84–8.98), and there was a suggestion of a 2-fold risk associated with high psychological stress (rate ratio = 2.02, 95% CI: 0.69–5.91). Without real-time monitoring of exposure reporting, preservation of the temporal exposure–disease relationship—an implicit assumption of the prospective cohort study design—may be particularly tenuous when transient exposures are investigated longitudinally.

Keywords: Recall bias, Time-varying exposures, Infection, Herpes, Prospective studies, Bias (epidemiology)