Comparison 2. Tramadol versus active treatment.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Pain	10		Std. Mean Difference (Fixed, 95% CI)	0.12 [0.01, 0.22]
1.1 Tramadol alone vs acetaminophen	1		Std. Mean Difference (Fixed, 95% CI)	0.13 [‐0.80, 1.06]
1.2 Tramadol alone vs NSAIDs	3		Std. Mean Difference (Fixed, 95% CI)	0.21 [0.07, 0.36]
1.3 Tramadol alone vs other opioids	4		Std. Mean Difference (Fixed, 95% CI)	‐0.11 [‐0.33, 0.12]
1.4 Tramadol in combination with acetaminophen vs NSAIDs	2		Std. Mean Difference (Fixed, 95% CI)	0.12 [‐0.16, 0.39]
1.5 Tramadol in combination with acetaminophen vs other opioids	1		Std. Mean Difference (Fixed, 95% CI)	0.06 [‐0.31, 0.43]
2 Physical function	4		Std. Mean Difference (Fixed, 95% CI)	0.23 [0.09, 0.36]
2.1 Tramadol alone vs NSAIDs	3		Std. Mean Difference (Fixed, 95% CI)	0.23 [0.09, 0.37]
2.2 Tramadol in combination with acetaminophen vs NSAIDs	1		Std. Mean Difference (Fixed, 95% CI)	0.2 [‐0.21, 0.61]
3 Function: overall assessment	1	190	Risk Ratio (IV, Fixed, 95% CI)	1.32 [1.04, 1.68]
3.1 Tramadol alone vs other opioids	1	190	Risk Ratio (IV, Fixed, 95% CI)	1.32 [1.04, 1.68]
4 Number of participants experiencing any adverse even	5	663	Risk Ratio (IV, Fixed, 95% CI)	1.07 [0.96, 1.19]
4.1 Tramadol alone vs NSAIDs	1	128	Risk Ratio (IV, Fixed, 95% CI)	1.31 [1.03, 1.67]
4.2 Tramadol alone vs other opioids	3	438	Risk Ratio (IV, Fixed, 95% CI)	0.99 [0.87, 1.13]
4.3 Tramadol in combination with acetaminophen vs NSAIDs	1	97	Risk Ratio (IV, Fixed, 95% CI)	1.17 [0.87, 1.57]
5 Number of participants who withdrew due to adverse events	6	1387	Risk Ratio (IV, Fixed, 95% CI)	2.07 [1.57, 2.73]
5.1 Tramadol alone vs acetaminophen	1	20	Risk Ratio (IV, Fixed, 95% CI)	5.0 [0.27, 92.62]
5.2 Tramadol alone vs NSAIDs	2	929	Risk Ratio (IV, Fixed, 95% CI)	1.88 [1.27, 2.76]
5.3 Tramadol alone vs other opioids	3	438	Risk Ratio (IV, Fixed, 95% CI)	2.26 [1.52, 3.37]
6 Number of participants experiencing any serious adverse events	7	698	Risk Ratio (IV, Fixed, 95% CI)	1.31 [0.16, 10.79]
6.1 Tramadol alone vs NSAID	2	188	Risk Ratio (IV, Fixed, 95% CI)	0.21 [0.01, 4.34]
6.2 Tramadol alone vs other opioids	4	495	Risk Ratio (IV, Fixed, 95% CI)	7.42 [0.39, 141.00]
6.3 Tramadol in combination with acetaminophen vs NSAIDs	1	15	Risk Ratio (IV, Fixed, 95% CI)	0.0 [0.0, 0.0]
7 Symptoms of opioid dependence: propensity for abuse	1	97	Risk Ratio (IV, Fixed, 95% CI)	1.03 [0.62, 1.74]
7.1 Tramadol alone vs NSAIDs	1	97	Risk Ratio (IV, Fixed, 95% CI)	1.03 [0.62, 1.74]