bwallace/OpenMeta-analyst- — Issue #127: Meta-regression: maybe wrong results?
Author: ethanbalk
Created: 2011-12-08 19:24:00+00:00
State: open

Maybe I just don't know how to interpret things. But the renal biopsy/hematuria database is giving what seems to me contradictory results. Maybe this is an example of subgroup and metaregression not agreeing (does that happen)?

Overall (by MA):
Binary Random-Effects Model (Proportion)
+-----------------------------------------------------------------------+
| Estimate | Lower bound | Upper bound | Std. error | p-Value | Z-Value |
|-----------------------------------------------------------------------|
| 0.041 | 0.029 | 0.054 | 0.006 | < 0.001 | 6.467 |
+-----------------------------------------------------------------------+

Subgroup (by MA)
Binary Random-Effects Model (Metric: Proportion)
+---------------------------------------------------------------------------------------------------------------------+
| Studies | Estimate | Lower bound | Upper bound | Std. error | p-Val | Z-Val | Q (df) | Het. p-Val | I^2 |
|---------------------------------------------------------------------------------------------------------------------|
| Subgroup 0 | 0.035 | 0.02 | 0.049 | 0.007 | < 0.001 | 4.749 | 4.564 (4) | 0.335 | 12 % |
|---------------------------------------------------------------------------------------------------------------------|
| Subgroup 1 | 0.042 | 0.028 | 0.057 | 0.007 | < 0.001 | 5.751 | 183.598 (15) | < 0.001 | 92 % |
|---------------------------------------------------------------------------------------------------------------------|
| Overall | 0.041 | 0.029 | 0.054 | 0.006 | < 0.001 | 6.467 | 197.538 (20) | < 0.001 | 90 % |
+---------------------------------------------------------------------------------------------------------------------+

Metaregression
+---------------------------------------------------------------------------------------------+
| Covariate | Level | Estimate | Std. error | p-Value | Z-Value | Lower bound | Upper bound |
|---------------------------------------------------------------------------------------------|
| Intercept | | 0.034 | 0.007 | < 0.001 | 5.081 | 0.021 | 0.047 |
|---------------------------------------------------------------------------------------------|
| passes_gte2 | 0 | | | | | | |
|---------------------------------------------------------------------------------------------|
| | 1 | -0.021 | 0.007 | -0.021 | -0.021 | -0.021 | -0.021 |
+---------------------------------------------------------------------------------------------+

Maybe the -0.021 is wrong for the same reason that's causing it to show up for p-value, z-value, etc.
But if it's "right", then my understanding is that the summary estimate for the passes = 1 group is (0.034-0.021 = 0.013), which is very different from 0.042