title: A randomized, controlled trial of in-home drinking water intervention to reduce gastrointestinal illness.
abstract: Trials have provided conflicting estimates of the risk of gastrointestinal illness attributable to tap water. To estimate this risk in an Iowa community with a well-run water utility with microbiologically challenged source water, the authors of this 2000-2002 study randomly assigned blinded volunteers to use externally identical devices (active device: 227 households with 646 persons; sham device: 229 households with 650 persons) for 6 months (cycle A). Each group then switched to the opposite device for 6 months (cycle B). The active device contained a 1-microm absolute ceramic filter and used ultraviolet light. Episodes of "highly credible gastrointestinal illness," a published measure of diarrhea, nausea, vomiting, and abdominal cramps, were recorded. Water usage was recorded with personal diaries and an electronic totalizer. The numbers of episodes in cycle A among the active and sham device groups were 707 and 672, respectively; in cycle B, the numbers of episodes were 516 and 476, respectively. In a log-linear generalized estimating equations model using intention-to-treat analysis, the relative rate of highly credible gastrointestinal illness (sham vs. active) for the entire trial was 0.98 (95% confidence interval: 0.86, 1.10). No reduction in gastrointestinal illness was detected after in-home use of a device designed to be highly effective in removing microorganisms from water.
authors.affiliation: Centers for Occupational and Environmental Health and Family and Community Health, University of California, Berkeley, School of Public Health, Berkeley, CA, USA. jcolford@socrates.berkeley.edu
authors.forename: John M
authors.initials: JM
authors.lastname: Colford
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wade
authors.forename: Sukhminder K
authors.initials: SK
authors.lastname: Sandhu
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Wright
authors.forename: Sherline
authors.initials: S
authors.lastname: Lee
authors.forename: Susan
authors.initials: S
authors.lastname: Shaw
authors.forename: Kim
authors.initials: K
authors.lastname: Fox
authors.forename: Susan
authors.initials: S
authors.lastname: Burns
authors.forename: Anne
authors.initials: A
authors.lastname: Benker
authors.forename: M Alan
authors.initials: MA
authors.lastname: Brookhart
authors.forename: Mark
authors.initials: M
authors.lastname: van der Laan
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Levy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004326:Drinking; D005260:Female; D005767:Gastrointestinal Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control*; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000592:standards*