Summary odds ratio of an adverse clinical outcome (ie, cancer recurrence, death due to cancer recurrence, or overall mortality) across published observational studies comparing patients having or not having transfusion.

The univariate (unadjusted) results of the available studies are integrated separately for each cancer site. The data on colorectal and prostate cancer (representing 28 and 6 studies, respectively) are shown as reported by Vamvakas.17 The data on head and neck (14 studies), breast (10 studies), gastric (8 studies), lung (8 studies), and cervical cancer (6 studies) are shown as reported by Brand and Houbiers.18 The references to the included primary studies can be found in the reports of these 2 meta-analyses.17 18Each summary OR is surrounded by its 95% CI. A summary OR of the null value (1) indicates that the risk of an adverse clinical outcome is the same, on average, with or without transfusion across the combined studies. When the 95% CI of the summary OR extends on both sides of the null value, the calculated summary TRIM effect is not statistically significant.