Study selection
This network meat-analysis was conducted stricktly with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (30).
24 eligible studies, including 26 trials, were finally identified (31-54). The details of the selection process is shown in Supplementary appendix Figure 1. Six treatment arms (anti-Interleukin-1α/β dual variable domain immunoglobulins (ALI), selective cox-2 inhibitors (SCI), NSADIs (NSA), duloxetine (DUL), opioids (OPI) and placebo (PLA)) were included into the network (Figure 1).
Study characteristics
11858 patients were assessed in this study. Most of included 26 trials studied on knee or hip OA, only two trials with 541 patients studied on hand OA.
Across the trials, the mean age of the patients was 62.35 years (ranged from 58.15 to 60.00 years), the proportion of male patients was 30.22% (ranged from 15.31% to 54.03%), and the median follow-up was 84 days (IQR 42–89.25 days). The number of patients enrolled for each treatment were 326 (ALI), 2518 (SCI), 3985 (NSA), 621 (DUL), 1405 (OPI) and 3033 (Placebo) respectively.
The details of baseline characteristics are presented in Supplementary appendix Table 1. The methodological quality and bias-risk evalutions of all included studies are presented in Supplementary appendix Table 2. Based on this results, the main contributing factors to risks of bias were performance bias, selection bias, and attrition bias.
Primary efficacy endpoint
Conventional direct meta-analysis
22 trials comparing 5 drugs with placebo were analysized. The random-effects model was used because of the heterogeneity of the included studies and interventions.
No significant difference was found in the comparison of placebo, with ALI (SMD 1.118, 95% CI [-0.374 to 2.610]) and OPI (SMD 1.914, 95% CI [-2.833 to 6.660]). The efficacies of other treatments were all stronger to placebo for pain relief. DUL had the largest efficacy for pain relief (SMD 4.764, 95% CI [3.895 to 5.632]). The details of the direct meta-analyses for all treatments compared with placebo are presented in Table 1.
Network meta-analysis
26 trials were analyzed in pain-relief network. No significant inconsistency was reported in global inconsistency tests and node-split tests, and then the consistency model was used.
DUL was the most efficacious treatment for pain relief (SMD compared with placebo 4.76, 95% CI [2.35 to 7.17]), while both ADL (SMD 1.11, 95% CI [-2.29 to 4.52]) and OPI (SMD 1.65, 95% CI [-1.53 to 4.83]) showed no benifit compared with placebo (Figure 2 and Table 2). According to the SUCRA value, DUL had the largest effect for pain relief (SUCRA=88.7%), followed by SCI (SUCRA=88.4%), and lastly ALI (SUCRA=28.6%). The detailed results of the SURCA rank are presented in Supplementary appendix Table 3.
Secondary efficacy endpoint
Conventional direct meta-analysis
Except for ALI (SMD 0.99, 95% CI [-2.27 to 2.417]) and OPI (SMD 1.700, 95% CI [-2.920 to 6.320]), all of other treatments were superior to placebo. SCI had the highest efficacy for physical function improvement (SMD 4.498, 95% CI [2.402 to 6.594]). The details of the direct meta-analyses for all treatments compared with placebo are presented in Table 1.
Network meta-analysis
A total of 26 trials were included into the function-improvement network. No significant inconsistency was found, the consistency model was more statistically suitable than the inconsistency model.
Similar to the results of direct meta-analysis, non significant difference was found in the comparision of placebo with ALI (SMD 0.992, 95% CI [-0.433 to 4.25]) and OPI (SMD 1.12, 95% CI [-1.92 to 4.17]), and SCI was the most efficacious treatment for physical function improvement (SMD 3.94, 95% CI [2.48 to 5.40]) (Figure 2 and Table 2). The result of most SURCA ranking showed that the most efficacious treatment was SCI (SUCRA=88.4%), and the least effective one was ALI (SUCRA=29.6%) (Supplementary appendix Table 3).
Safety endpoint
Conventional direct meta-analysis
20 trials involving all 5 therapies were analysized in the conventional direct meta-analyses. There was no significant heterogeneity reported, and fixed-effects model was used. DUL, NSA and OPI had greater rates for all of safety endpoints compared with placebo, while ALI and SCI did not show a a significantly higher risk for any safety endpoint. The details of the pairwise meta-analysis for all drugs compared with placebo are shown in Table 1.
Network meta-analysis
24 trials involving all 5 treatments were analyzed in the safety network. Node-split tests and global inconsistency tests were performed, and no inconsistency was reported. The consistency model was preferred rather than the inconsistency model.
All treatments had neither more withdrawals due to AE, nor higher incidence of serious AEs, nor any drug-related AEs. Based on the results of network comparision, SCI has the lowest rate of withdrawal due to AEs (SURCA 92.6%, OR -0.11, 95% CI [-0.40 to 0.17]), the lowest rate of serious AEs (SURCA 80.2%, OR -0.01, 95% CI [-0.70 to 0.68]) and the lowest rate of drug-related AEs (SURCA 75.5%, OR 0.07, 95% CI [-0.10 to 0.24]). The cluster rank plots showed that SCI was the optimum treatment from the perspective of safety and efficacy (The results of cluster-rank plots can be seen in Supplementary appendix Figure 2). The relative safety between different treatments was presented in Table 3. The SURCA and relative safety compare to placebo are presented in Supplementary appendix Table 4.
Subgroup analysis
Two subgroup analyses were conducted.
The first subgroup analysis was conducted exploited the impacts of different drug delivery route. Three of the 26 trials used topical drug delivery methods. After excluding these studies, no substantial change was revealed samely. DUL had the largest efficacy for pain relief (SMD 4.76, 95% CI [2.33 to 7.19]), and SCI for function improvement (SMD 4.19, 95% CI [2.70 to 5.68]). No tratment showed a higher risk of any safety endpoint (Supplementary appendix Table 5).
In the second one, there were only two trials studied on hand joint while others all studied on knee or hip joints. After excluding these studies, no substantial change was reported. Simlarily, DUL had the highest effect for pain relief (SMD 4.76, 95% CI [2.32 to 7.20]), and SCI for function improvement (SMD 4.07, 95% CI [2.59 to 5.55]). No tratment showed a higher risk of any safety endpoint (Supplementary appendix Table 5).