Table 1.

Advantages and disadvantages of incorporating both randomized controlled trials and non-randomized comparative cohort studies in network meta-analysis

Advantages

• Non-randomized studies can complement randomized controlled trials or address some of their limitations, such as short follow-up time, small sample size, highly selected population, high cost, and ethical restrictions.

• Incorporating both types of data allows assessments of multiple treatments simultaneously, including treatments that may not have been studied in randomized controlled trials.

• Incorporating both types of data allows larger sample size and more diverse populations, thereby improving the generalizability of the findings.

• Incorporating non-randomized studies might improve network density and connect disconnected networks.

Disadvantages

• Including low-quality, non-randomized comparative cohort studies could perpetuate the biases that are unknown, unmeasured, or uncontrolled.

• There is a greater risk of violating the exchangeability assumption of network meta-analysis, especially if broad populations are considered.

• The analysis may be more complex, time- and resource-intensive, and less understood than network meta-analysis that only includes randomized controlled trials.