Table 2. Meta-Regression of Potential Sources of Heterogeneity in the Pooled All-Cause Crude Mortality Rate and Standardized Mortality Ratio.
| Characteristic | Mortality | |||||||
|---|---|---|---|---|---|---|---|---|
| Crude Rate | Standardized Ratio | |||||||
| No. of Studies | Coefficient (SE) | Adjusted R2, % | P Value | No. of Studies | Coefficient (SE) | Adjusted R2, % | P Value | |
| Cohort characteristics at baseline | ||||||||
| Percentage drug injectors | 43 | 4.297 (1.818) | 22.67 | .001 | 16 | 7.592 (4.725) | 43.41 | .006 |
| Percentage male | 76 | 2.316 (1.745) | –0.26 | .27 | 30 | 2.305 (2.908) | –1.89 | .51 |
| Mean or median age | 42 | 1.000 (0.022) | –2.65 | .99 | 19 | 0.953 (0.027) | 10.97 | .10 |
| Percentage HIV positive | 23 | 13.569 (12.041) | 27.68 | .008 | 10 | 107.159 (270.897) | 21.99 | .10 |
| Percentage HCV positive | 19 | 4.134 (2.478) | 19.73 | .03 | 6 | 12.924 (19.898) | 27.35 | .17 |
| Percentage with history of homelessness | 8 | 11.081 (20.865) | 7.24 | .25 | 3 | 0 (0) | 91.52 | .16 |
| History of incarceration | 16 | 0.736 (0.399) | –4.11 | .58 | 6 | 0.674 (0.514) | –19.27 | .63 |
| Study characteristic | ||||||||
| Year of follow-up completion | ||||||||
| Completed by end of 1994 | 7 | Reference | Reference | Reference | 4 | Reference | Reference | Reference |
| Continued or commenced since 1995 | 90 | 0.851 (0.266) | –0.91 | .61 | 39 | 1.058 (0.384) | –2.55 | .88 |
| Sample size | 95 | 1.000 (0) | –0.19 | .39 | 41 | 1.000 (0) | 7.74 | .05 |
| Person-years of follow-up | 96 | 1.000 (0) | 0.66 | .25 | 39 | 1.000 (0) | 6.43 | .07 |
| Recruitment setting | ||||||||
| Drug treatment or harm reduction setting | 57 | Reference | Reference | Reference | 29 | Reference | Reference | Reference |
| Other settingsa | 40 | –0.023 (0.167) | –1.25 | .89 | 14 | 0.927 (0.209) | –2.27 | .74 |
Abbreviation: HCV, hepatitis C virus.
a
Other settings include acute care (eg, emergency departments), prisons, and community settings.