Table 3.
Sensitivity Analysis for Secondary Outcome, CIN
| Subgroups of Studies | Studies Included | Summary RR | 95% CI | P Homogeneity* |
|---|---|---|---|---|
| Studies included in meta-analysis | 1–9 | 0.43 | 0.24 to 0.75 | .03 |
| High baseline Cr (Cr ≥2.0) | 3–5,8,9 | 0.50 | 0.21 to 1.20 | .02 |
| Low baseline Cr (Cr<2.0) | 1,2,6,7 | 0.35 | 0.19 to 0.62 | .51 |
| High quality† | 5,6 | 0.51 | 0.08 to 3.24 | .02 |
| Low quality | 1–4,7–9 | 0.40 | 0.22 to 0.71 | .14 |
| Studies using NAC 600 mg BID × 4 doses | 1,6–9 | 0.42 | 0.20 to 0.90 | .09 |
| Studies using high-dose PO NAC (≥1,000 mg/dose) | 4,5 | 0.78 | 0.30 to 2.04 | .14 |
| High mean contrast volume (vol ≥150 ml) | 2,6,7 | 0.35 | 0.16 to 0.74 | .32 |
| Low mean contrast volume (vol<150 ml) | 1,3–5,9 | 0.37 | 0.16 to 0.88 | .03 |
| High mean percentage with diabetes (≥50%) | 3,6 | 0.16 | 0.06 to 0.42 | .79 |
| Low mean percentage with diabetes (<50%) | 1,2,5,7–9 | 0.56 | 0.29 to 1.08 | .07 |
| Studies using 0.9 NS for hydration | 1,2 | 0.29 | 0.12 to 0.70 | .75 |
| Studies using 0.45 NS for hydration | 3–9 | 0.46 | 0.23 to 0.91 | .02 |
| All controlled studies reporting CIN | 1–10,14,15 | 0.50 | 0.29 to 0.86 | <.01 |
| Randomized, placebo-controlled | 1,3–6,9,13 | 0.33 | 0.15 to 0.73 | .03 |
| Studies using oral NAC formulation | 1,3–9 | 0.45 | 0.24 to 0.82 | .03 |
| Studies using intra-arterial contrast | 1–8 | 0.46 | 0.26 to 0.82 | .04 |
Relative risk of CIN, NAC versus placebo. Calculations were done using a random effects model. Study numbers are referenced from Table 1.
*
Heterogeneity is present when P<.1.
†
Define quality as: explicitly complying with 2 or more of predefined quality features from abstraction form. These include appropriate randomization, allocation concealment, blinded patients, and blinded providers. Analysis includes excluded studies.
CIN, contrast-induced nephropathy; RR, relative risk; CI, confidence interval; Cr, creatinine; NAC, N-acetylcysteine; NS, normal saline; BID, twice daily; PO, by mouth.