Table II.
Heterogeneity tests for overall survival.
| Testa | Null vs. alternative/thresholds | Measure | Df | χ2 | Prob level |
|---|---|---|---|---|---|
| Cochran's Q | H0: all studies are evaluating the same effect | Risk ratio | 8 | χ2=13.7 | 0.089928 |
| Ha: not all studies are evaluating the same effect | |||||
| I2 | 0 to 40%: may not be important | Risk ratio | I2=42 | ||
| 30 to 60%: may represent moderate heterogeneity | |||||
| 50 to 90%: may represent substantial heterogeneity | |||||
| 75 to 100%: Indicates considerable heterogeneity |
a
Tests performed with RevMan. Cochran's Q and I2 tests demonstrated that the null hypothesis may be rejected at 5% level of significance and that the included studies exhibited moderate heterogeneity. Df, degree of freedom.