Volume 8, Number 1—January 2002
Research
Participant Blinding and Gastrointestinal Illness in a Randomized, Controlled Trial of an In-Home Drinking Water Intervention
John M. Colford*†
, Judy R. Rees*†, Timothy J. Wade*†, Asheena Khalakdina*†, Joan F. Hilton‡, Isaac J. Ergas*, Susan Burns*, Anne Benker*, Catherine Ma, Cliff Bowen, Daniel C. Mills, Duc J. Vugia, Dennis D. Juranek¶, and Deborah A. Levy¶
, Judy R. Rees*†, Timothy J. Wade*†, Asheena Khalakdina*†, Joan F. Hilton‡, Isaac J. Ergas*, Susan Burns*, Anne Benker*, Catherine Ma, Cliff Bowen, Daniel C. Mills, Duc J. Vugia, Dennis D. Juranek¶, and Deborah A. Levy¶Table 3
Episodesa of highly credible gastrointestinal illness (HCGI) and days of illness, Pilot Water Evaluation Trial
| Sham device group | Active device group | Total | |
|---|---|---|---|
| Total episodes of HCGI, defined byb | 103 | 82 | 185 |
| Vomiting | 18 | 30 | 48 |
| Watery diarrhea | 73 | 42 | 115 |
| Soft diarrhea with abdominal cramps | 7 | 6 | 13 |
| Nausea with abdominal cramps | 16 | 17 | 33 |
| Total days of HCGI, defined byb | 261 | 190 | 451 |
| Vomiting | 35 | 78 | 113 |
| Watery diarrhea | 207 | 99 | 306 |
| Soft diarrhea with abdominal cramps | 8 | 8 | 16 |
| Nausea with abdominal cramps | 31 | 30 | 61 |
| Total days at risk for HCGI episodes | 10,790 | 11,380 | 22,170 |
| Total days of observation | 11,642 | 12,036 | 23,678 |
aA new episode was defined as the presence of any of four definitions of HCGI, preceded by 6 HCGI-free days. The difference in total episodes of HCGI was the principal a priori health outcome measure for the study.
bBecause individual participants could report multiple definitions of HCGI on the same day, the total episodes of HCGI (and total days of HCGI) are less than the sums of the individual definitions.
