I am doing a meta analysis for the first time and have a few basic questions regarding statistical analysis. Let's say I have one study where the primary outcome (thrombosis) in the 2 treatment groups (intervention v. placebo) was compared using the Mantel-Haenszel chi-square test. It does not report df in the article (is this something I can deduce?). Then it tells me that "Treatment effects were expressed as a weighted average of the strata-specific relative risks." Is this something I need to consider for the meta-analysis statistical calculation? If so, what does it mean? In the results we learn "Among the 866 participants who had patency assessed, the primary outcome of fistula thrombosis at 6 weeks occurred in 53 participants (12.2%) in the clopidogrel group compared with 84 participants (19.5%) in the placebo group (relative risk, 0.63; 95% CI, 0.46-0.97;P=.018).
What do I do with all this information? I tried using a computerized program, but I didn't know what to fill all the blanks in with...
In the second study, we have the following: "The hazard ratio was 0.81 (95% CI, 0.47 to 1.40) in favor of aspirin and clopidogrel therapy, but the reduction was not significant (P= 0.45). Although the event rates in the two treatment arms converged, there was no evidence that the proportional-hazards assumption was violated (P 0.53). The annual hazard rate for thrombosis among articipants receiving placebos was 0.59 (95% CI, 0.39 to 0.87), compared with 0.47 (95% CI, 0.31 to 0.71) among participants receiving aspirin and clopidogrel. The absolute risk reduction for the group receiving aspirin and clopidogrel was 0.03 (95% CI,-0.19 to 0.07), and the number needed to treat was 33.3 (95% CI, 14.9 to >/=1000)." Regarding analysis, it states: "The cumulative incidence of the first episode of thrombosis was estimated with the Kaplan-Meier method, and differences in rates between treatment groups were tested with the log rank test. The cumulative incidence of the first bleeding event was analyzed in a similar manner."
What do I do with all this information? Thank you for any help you can provide.