RESUMEN
OBJECTIVE: To evaluate the difference between combination pharmacotherapy and monotherapy on low back pain (LBP). METHODS: We searched PubMed, Embase, and Cochrane Central Register of Controlled Trials databases up to March 14, 2017. Two authors independently extracted the data and assessed the validity of included trials. RESULTS: Twelve randomized controlled trials comparing the effect of LBP combination pharmacotherapy to monotherapy or placebo were included. In chronic LBP, combination pharmacotherapy was more effective than placebo in pain relief (P<0.001; standardized mean difference [SMD], -0.50; 95% confidence interval [CI], -0.70 to -0.29; I²=0%) and function improvement (P<0.001; SMD, -0.27; 95% CI, -0.41 to -0.13; I²=0%) and showed improved pain relief compared with monotherapy (P<0.001; SMD, -0.84; 95% CI, -1.12 to -0.56; I²=0%). Combination pharmacotherapy did not outperform monotherapy pain relief and function improvement in acute LBP. In addition, risk of adverse effects of combination pharmacotherapy was much higher compared with placebo (P<0.05; relative risk, 1.80; 95% CI, 1.33-2.42; I²>50%) and monotherapy (P<0.05; relative risk, 1.44; 95% CI, 1.01-2.06; I²>50%) in both settings. DISCUSSION: Combination pharmacotherapy is more effective than placebo or monotherapy in the management of pain and disability in chronic LBP, but not in acute LBP. Further, combination pharmacotherapy has a higher risk of adverse effects than placebo and monotherapy.