TY - JOUR AU - Colford, John M. AU - Rees, Judy R. AU - Wade, Timothy J. AU - Khalakdina, Asheena AU - Hilton, Joan F. AU - Ergas, Isaac J. AU - Burns, Susan AU - Benker, Anne AU - Ma, Catherine AU - Bowen, Cliff AU - Mills, Daniel C. AU - Vugia, Duc J. AU - Juranek, Dennis D. AU - Levy, Deborah A. T1 - Participant Blinding and Gastrointestinal Illness in a Randomized, Controlled Trial of an In-Home Drinking Water Intervention T2 - Emerging Infectious Disease journal PY - 2002 VL - 8 IS - 1 SP - 29 SN - 1080-6059 AB - We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was “highly credible gastrointestinal illness” (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention. KW - water supply KW - bias KW - epidemiology KW - double-blind method KW - filtration KW - gastrointestinal diseases KW - public health KW - randomized controlled trials KW - standards KW - sanitation KW - water microbiology KW - bias, epidemiology, double-blind method, filtration, gastrointestinal diseases, public health, randomized controlled trials, standards KW - sanitation, water microbiology KW - United States DO - 10.3201/eid0801.001481 UR - https://wwwnc.cdc.gov/eid/article/8/1/00-1481_article ER - End of Reference