Dropout in a longitudinal, cohort study of urologic disease in community men

BMC Med Res Methodol. 2006 Dec 14:6:58. doi: 10.1186/1471-2288-6-58.

Abstract

Background: Reasons for attrition in studies vary, but may be a major concern in long-term studies if those who drop out differ systematically from those who continue to participate. Factors associated with dropout were evaluated in a twelve-year community-based, prospective cohort study of urologic disease in men.

Methods: During 1989-1991, 2,115 randomly selected Caucasian men, ages 40-79 years from Olmsted County, Minnesota were enrolled and followed with questionnaires biennially; 332 men were added in follow-up. A random subset (approximately 25%) received a urologic examination. Baseline characteristics including age, benign prostatic hyperplasia (BPH) symptoms, comorbidities, and socioeconomic factors were compared between subjects who did and did not participate after the twelfth year of follow-up.

Results: Of the 2,447 men, 195 died and were excluded; 682 did not participate in 2002. Compared with men in the 40-49 year age group, men > or = 70 years of age at baseline had a greater relative odds of dropout, 2.65 (95% CI: 1.93, 3.63). In age-adjusted analyses, relative to men without stroke, men who had suffered a stroke had a higher odds of dropout, age-adjusted OR 3.07 (95% CI: 1.49, 6.33). Presence of at least one BPH symptom was not associated with dropout, (age-adjusted OR 1.12 (95% CI: 0.93, 1.36)).

Conclusion: These results provide assurance that dropout was not related to primary study outcomes. However, factors associated with dropout should be taken into account in analyses where they may be potential confounders.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Cohort Studies
  • Health Status
  • Humans
  • Male
  • Middle Aged
  • Minnesota / epidemiology
  • Patient Dropouts / psychology*
  • Patient Dropouts / statistics & numerical data
  • Patient Selection
  • Prospective Studies
  • Prostatic Diseases / diagnosis*
  • Prostatic Diseases / etiology
  • Prostatic Diseases / psychology
  • Quality of Life
  • Research Subjects / psychology*
  • Residence Characteristics
  • Social Class
  • Surveys and Questionnaires
  • Urologic Diseases / complications
  • Urologic Diseases / diagnosis*
  • Urologic Diseases / psychology