Table 3

Quality of evidence in the primary and secondary outcomes rated as high, moderate, low, and very low using the GRADE method based on the risk of bias in the study, inconsistency in the results, indirectness of evidence, imprecision of results, and publication bias.

Outcomes	Quality of evidence	Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias
Pain intensity at rest
0–4 hours after surgery	Low	High*	Moderate†	High	High	High
5–12 hours after surgery	Low	High*	Moderate†	High	High	High
13–24 hours after surgery	Low	High*	Moderate†	High	High	High
25–48 hours after surgery	Low	High*	Moderate†	High	High	High
49–72 hours after surgery	Moderate	High*	High	High	High	High
Pain intensity during coughing
0–4 hours after surgery	Low	High*	Moderate†	High	High	High
5–12 hours after surgery	Low	High*	Moderate†	High	High	High
13–24 hours after surgery	Low	High*	Moderate†	High	High	High
25–48 hours after surgery	Low	High*	Moderate†	High	High	High
49–72 hours after surgery	Moderate	Low	Moderate†	High	High	High
Incidence of chronic pain
1 month after surgery	Moderate	High*	High	High	High	High
2 months after surgery	Moderate	High*	High	High	High	High
3 months after surgery	Moderate	High*	High	High	High	High
6 months after surgery	Moderate	High*	High	High	High	High
Intensity of chronic pain
1 month after surgery	Low	High*	High	High	Moderate‡	High
2 months after surgery	Moderate	Low	High	High	Moderate‡	High
3 months after surgery	Low	Low	Moderate†	High	Moderate‡	High
6 months after surgery	Low	High*	High	High	Moderate‡	High
Postoperative epidural analgesic consumption	Low	High*	Moderate†	High	High	High
Postoperative systemic analgesic consumption	Low	High*	Moderate^†	High	High	High
Forced vital capacity 24 hours after surgery (l)	Very low	High*	Moderate†	High	Moderate‡	High
Forced vital capacity 48 hours after surgery (l)	Low	High*	High	High	Moderate‡	High
Forced expiratory volume in 1 s 24 hours after surgery (l)	Very low	High*	Moderate†	High	Moderate‡	High
Forced expiratory volume in 1 s 48 hours after surgery (l)	Very low	High*	Moderate†	High	Moderate‡	High
Satisfaction with pain management at discharge	Low	Low	Moderate†	High	Moderate‡	High
Satisfaction with pain management 6 months after surgery	Moderate	Low	High	High	Moderate‡	High
Length of hospital stay (day)	Very low	High*	Moderate†	High	Moderate‡	High
Nausea or vomiting	Moderate	High*	High	High	High	High
Pruritus	Moderate	High*	High	High	High	High
Respiratory depression	Low	High*	High	High	Moderate‡	High
Sedation	Low	High*	High	High	Moderate‡	High
Hypotension	Low	High*	High	High	Moderate‡	High
Urinary retention	Moderate	Low	High	High	Moderate^‡	High

*Downgraded by one level because of the studies with high risk of bias.
†Downgraded by one level because of substantial statistical heterogeneity of I²>50%.
‡Downgraded by one level because of a wide CI of the results.
GRADE, Grading of Recommendations, Assessment, Development and Evaluation.