Table 4. Possible sources of variation... | American Society of Hematology

Table 4.

Possible sources of variation in the findings of the available randomized controlled trials investigating the association between perioperative allogeneic blood transfusion and postoperative bacterial infection: integration of the findings of studies sharing a particular design characteristic by a meta-analysis

Study attribute	Categories of study attribute	Number of studies	Q test statistic: Pvalue	Summary odds ratio^4-150
Study attribute	Categories of study attribute	Number of studies	Q test statistic: Pvalue	Point estimate	95% confidence interval
Study organization	Single center3-7	5	> .05	2.29^4-151	1.35-3.87^4-151
	Multicenter22 23	2	.95	0.88	0.69-1.12
Surgical setting	Open heart surgery⁶	1	N/A^‡	1.42^4-153	1.00-1.99^4-153
	Elective abdominal surgery3-5,7,22 23	6	< .001	N/A^4-155	N/A^4-155
Homogeneity of patients having	Colorectal cancer4,22 23	3	> .10	0.96	0.67-1.37
elective abdominal surgery: diagnosis	Any disease of the colorectum³⁵ or gastrointestinal tract⁷	3	> .25	2.95^4-151	1.73-5.05^4-151
RBC product transfused to the	Allogeneic whole blood³	1	N/A^‡	7.32^4-154	1.62-33.12^4-154
treatment arm	Allogeneic RBCs⁷	1	N/A^‡	1.85^4-154	0.89-3.85^4-154
	Buffy-coat–reduced RBCs4-6,22 23	5	< .001	N/A^4-155	N/A^4-155
RBC product transfused to the	Autologous RBCs⁴ or whole blood²³	2	> .05	1.35	0.45-4.08
control arm	WBC-reduced allogeneic RBCs5-7 22 or whole blood³	5	< .001	N/A^4-155	N/A^4-155
	WBC-reduced allogeneic RBCs5-7 22	4	< .001	N/A^4-155	N/A^4-155
	Fresh-filtered, WBC-reduced allogeneic RBCs6 22	2	< .05	N/A^4-155	N/A^4-155
	WBC-reduced allogeneic RBCs or whole blood filtered after storage3,5 6	3	< .01	N/A^4-155	N/A^4-155
Overall	Exceeding 20%22 23	2	.95	0.88	0.69-1.12
postoperative infection rate#	20% or lower3-7	5	> .05	2.29^4-151	1.35-3.87^4-151
Overall percentage	Less than 50%⁵⁷	2	> .10	2.73^4-151	1.48-5.04^4-151
of patients having	50% to 67%3,22 23	3	> .10	0.96	0.62-1.49
transfusion#	More than 67%⁴⁶	2	> .25	1.53^4-151	1.00-2.33^4-151
Reported by Jensen	Jensen et al³⁵	2	.50	3.68	2.11-6.43
et al or by other teams of investigators	Other teams4,6,7,22 23	5	> .05	1.17	0.84-1.62

Study attribute	Categories of study attribute	Number of studies	Q test statistic: Pvalue	Summary odds ratio^4-150
Study attribute	Categories of study attribute	Number of studies	Q test statistic: Pvalue	Point estimate	95% confidence interval
Study organization	Single center3-7	5	> .05	2.29^4-151	1.35-3.87^4-151
	Multicenter22 23	2	.95	0.88	0.69-1.12
Surgical setting	Open heart surgery⁶	1	N/A^‡	1.42^4-153	1.00-1.99^4-153
	Elective abdominal surgery3-5,7,22 23	6	< .001	N/A^4-155	N/A^4-155
Homogeneity of patients having	Colorectal cancer4,22 23	3	> .10	0.96	0.67-1.37
elective abdominal surgery: diagnosis	Any disease of the colorectum³⁵ or gastrointestinal tract⁷	3	> .25	2.95^4-151	1.73-5.05^4-151
RBC product transfused to the	Allogeneic whole blood³	1	N/A^‡	7.32^4-154	1.62-33.12^4-154
treatment arm	Allogeneic RBCs⁷	1	N/A^‡	1.85^4-154	0.89-3.85^4-154
	Buffy-coat–reduced RBCs4-6,22 23	5	< .001	N/A^4-155	N/A^4-155
RBC product transfused to the	Autologous RBCs⁴ or whole blood²³	2	> .05	1.35	0.45-4.08
control arm	WBC-reduced allogeneic RBCs5-7 22 or whole blood³	5	< .001	N/A^4-155	N/A^4-155
	WBC-reduced allogeneic RBCs5-7 22	4	< .001	N/A^4-155	N/A^4-155
	Fresh-filtered, WBC-reduced allogeneic RBCs6 22	2	< .05	N/A^4-155	N/A^4-155
	WBC-reduced allogeneic RBCs or whole blood filtered after storage3,5 6	3	< .01	N/A^4-155	N/A^4-155
Overall	Exceeding 20%22 23	2	.95	0.88	0.69-1.12
postoperative infection rate#	20% or lower3-7	5	> .05	2.29^4-151	1.35-3.87^4-151
Overall percentage	Less than 50%⁵⁷	2	> .10	2.73^4-151	1.48-5.04^4-151
of patients having	50% to 67%3,22 23	3	> .10	0.96	0.62-1.49
transfusion#	More than 67%⁴⁶	2	> .25	1.53^4-151	1.00-2.33^4-151
Reported by Jensen	Jensen et al³⁵	2	.50	3.68	2.11-6.43
et al or by other teams of investigators	Other teams4,6,7,22 23	5	> .05	1.17	0.84-1.62

RBC(s) indicates red blood cell(s); WBC, white blood cell; N/A, not applicable.

F4-150

Calculated by the method of DerSimonian and Laird.56

F4-151

Statistically significant (P ≤ .05) summary odds ratio.

‡

Not applicable because only one study was available for meta-analysis.

F4-153

Odds ratio of postoperative infection in patients receiving buffy-coat–reduced RBCs, as compared with recipients of WBC-reduced, buffy-coat–reduced RBCs filtered before or after storage.

F4-155

P < .05 for the Q test statistic; accordingly, the results of the studies could not be integrated by a meta-analysis, and N/A is shown under the summary odds ratio.

F4-154

Odds ratio shown not as reported by the authors, but as recalculated according to an intention-to-treat analysis.

#In the entire study population regardless of randomization arm.

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