Table 4.
Stratified meta-analysis for animal studies, by stratification variable
| Number of studies (n=101) | Pooled absolute risk difference (95% CI) | Meta-regression p value | |
|---|---|---|---|
| Study population | |||
| Swine | 30 (30%) | −0·21 (−0·27 to −0·14) | 0·89 |
| Cattle | 24 (24%) | −0·04 (−0·06 to −0·03) | ·· |
| Poultry | 55 (54%) | −0·18 (−0·22 to −0·14) | ·· |
| Sample type | |||
| Retail | 25 (25%) | −0·15 (−0·19 to −0·10) | 0·99 |
| Non-retail | 79 (78%) | −0·14 (−0·16 to −0·12) | ·· |
| Strength of intervention | |||
| Stronger interventions* | 31 (31%) | −0·19 (−0·26 to −0·11) | 0·37 |
| Weaker interventions† | 70 (69%) | −0·13 (−0·15 to −0·11) | ·· |
| Level of antibiotic restriction | |||
| Complete restriction of all antibiotic use | 38 (38%) | −0·16 (−0·19 to −0·12) | 0·59 |
| Therapeutic antibiotic use allowed | 67 (66%) | −0·14 (−0·17 to −0·12) | ·· |
| Laboratory procedure to measure resistance | |||
| Disk diffusion | 32 (32%) | −0·15 (−0·19 to −0·10) | 0·16 |
| Broth or agar dilution | 53 (52%) | −0·11 (−0·13 to −0·09) | ·· |
| Use of selective media containing antibiotics | 11 (11%) | −0·16 (−0·31 to −0·01) | ·· |
| Other or undetermined | 6 (6%) | −0·30 (−0·50 to −0·11) | ·· |
| Recruitment of study populations | |||
| Same source population for intervention and comparator groups | 46 (46%) | −0·12 (−0·16 to −0·09) | 0·15 |
| Different source populations for intervention and comparator groups | 55 (54%) | −0·16 (−0·19 to −0·14) | ·· |
| Recruitment period | |||
| Intervention and comparator groups are recruited over the same time period | 75 (74%) | −0·12 (−0·14 to −0·10) | 0·21 |
| Intervention and comparator groups are not recruited over the same time period | 26 (26%) | −0·20 (−0·28 to −0·13) | ·· |
| Description of interventions | |||
| Well described interventions | 72 (71%) | −0·14 (−0·16 to −0·11) | 0·58 |
| Poorly described interventions | 29 (29%) | −0·17 (−0·21 to −0·12) | ·· |
| Adjustment for potential confounders | |||
| Adequate adjustment | 14 (14%) | −0·10 (−0·15 to −0·06) | 0·35 |
| Inadequate adjustment | 87 (86%) | −0·16 (−0·18 to −0·13) | ·· |
| Publications | |||
| Peer-reviewed publications | 90 (89%) | −0·15 (−0·17 to −0·13) | 0·33 |
| Non-peer reviewed publications‡ | 11 (11%) | −0·10 (−0·19 to −0·02) | ·· |
Studies might be included into more than one stratum if stratum-specific estimates were provided.
*
Externally imposed restrictions, and voluntary restrictions.
†
Self-reported organic, antibiotic-free, and related labels.
‡
Includes meeting abstracts, reports, and dissertations.