Table 4.
Characteristics of studies of hydraulic pipe integrity.a
| Study | Location | Source water | Treatment plant | Distribution system | Design | Exposure | Comparison exposure | Outcome assessment | Effect estimate(95% CI) |
|---|---|---|---|---|---|---|---|---|---|
| Continuous systems | |||||||||
| Fewtrell et al. 1997 | United Kingdom | Not reported | Not reported | Not reported | Ecological | No. of water outages in a ZIP code area | — | Surveillance records | Correlation coefficient: Shigella 0.42 (p = 0.07)a,bHep A 0.67 (p = 0.001)a,b |
| Hunter et al. 2005 | United Kingdom | Not reported | Effluent in compliance with regulations | Not reported | Cross-sectionalc | Water outage | No water outage | Self-report | OR = 12.50 (3.49, 44.71) |
| Nygård et al. 2007 | Norway | Not reported | Not reported | Not reported | Cohort | Water outage | No water outage | Self-report | OR = 2.00 (1.30, 3.20) |
| Nygård et al. 2007 | Norway | Not reported | Not reported | Not reported | Cross-sectionald | Water outage > 6 hr duration | Water outage ≤ 6 hr duration | Self-report | OR = 1.90 (1.00, 3.40)b |
| Özkan et al. 2007 | Turkey | Not reported | Not reported | Not reported | Cross-sectional | Water outage > 12 hr duration | No water outage > 12 hr duratione | Self-report | OR = 10.28 (2.95, 35.48) |
| Huang et al. 2011 | Taiwan | Not reported | Not reported | Not reported | Ecological | Days with water outagef | 10 days with normal water supply before water outage | Hospital records | IDR = 1.31 (1.26, 1.37) |
| Intermittent systems | |||||||||
| Cifuentes et al. 2002 | Mexico | Groundwater | Chlorination | Not reported | Cross-sectional | Intermittent supply | Full-day supply | Self-report | OR = 2.00 (1.16, 3.70) |
| Abu Mourad 2004 | Palestine | Groundwater | Not reported | Not reported | Cross-sectional | Intermittent supply | Full-day supply | Self-report | OR = 1.53 (1.15, 2.03)g |
| Yassin et al. 2006 | Palestine | Groundwater | Chlorination | Inadequate residual | Cross-sectional | Intermittency of > 1 day duration | Intermittency of 1-day duration | Self-report | RR = 1.33 (0.92, 1.91)g |
| Abu Amr and Yassin 2008 | Palestine | Groundwater | Chlorination | Inadequate residual | Cross-sectional | Intermittency of > 1 day duration | Intermittency of 1-day duration | Self-report | RR = 1.49 (1.06, 2.09)g |
| Abbreviations: IDR, incidence density ratio; OR, odds ratio; RR, relative risk.aResults from 1991; no summary result reported by authors for all years in study; authors found no evidence of a causative temporal link at individual level. bNot included in pooled analyses. cCross-sectional analysis within control group of case–control study. dCross-sectional analysis within exposed group of same cohort study. eAuthors specified water outages > 12 hr as a binary exposure variable; we assumed that the comparison exposure includes outages ≤ 12 hr as well as no outages. fEffect estimate was similar when the 10-day period following the outage was used as the exposure. gCalculated from data reported in study. | |||||||||