Study search and study characteristic
Of 3506 articles, 652 were screened after duplicates were deleted, 2830 were excluded by reviewing the title and abstract level, and additional 6 related studies were removed for unpublished data, observational trial or cannot be grouped[24, 25, 26, 27, 28, 29] (Figure 1). Eighteen trials were ultimately included with a total of 20536 diabetic patients randomly assigned to receive one of the following four kinds of DAPT durations: short-term (≤3-month), midterm (6-month), standard-term (12-month), extended-term (>12-month)[10, 11, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45]. Besides, short-term DAPT followed by aspirin monotherapy in comparison with P2Y12 monotherapy was conducted for further study. The characteristics of included RCTs for the NMA are shown in Table 1. Detailed inclusion and exclusion criteria of trials are represented in Additional file 3.
Quality of evidence
The detailed risk of bias assessments was summarized in Figure 2. The overall heterogeneity assessment of the results showed that the heterogeneity was low for cardiac mortality (I²= 0%), stroke (I²= 0%), TVR (I²= 6.27%) and major bleeding (I²= 0%). However, moderate to high heterogeneity was detected in comparisons of the primary endpoint (I²= 28.75%), all-cause mortality (I²= 28.19%), MI (I²= 25.51%), stent thrombosis (definite or probable) (I²= 64.76%) observation indicators, although the 95% CIs showed that this heterogeneity was not statistically significant. Forest plots of feasible pairwise comparisons with heterogeneity estimates were generated in Additional file 4.
The fit of the consistency model was similar to or better than that of the inconsistency model (Additional file 5). Inconsistency between direct and indirect estimates from the node splitting analysis did not show significant differences in each comparison (Additional file 6). The convergence diagnosis model can be used to predict the data effectively. We evaluated the convergence of iterations by visual inspection of the chains to establish homogenous parameter estimates and to comply with the Brooks – Gelman – Rubin diagnostic standard (Additional file 7).
Network meta-analysis
Efficacy and safety
Network plots for different outcomes were generated to illustrate the geometries, to clarify which treatments were compared directly or indirectly in the included studies[46]. The network evidence plot of primary endpoint and was shown in Figure 3, while that of short-term DAPT followed by P2Y12 inhibitor or aspirin monotherapy and secondary outcomes was shown in Additional file 8. All of contribution plot was also demonstrated in Additional file 8. Moreover, the primary endpoint result of NMA using random-effects were summarized in Table 2. Other NMA clinical events result were demonstrated in Additional file 9.
Primary endpoint
Compared with extended-term DAPT, short-term DAPT and standard-term DAPT was associated with a reduced risk of primary endpoint (OR 0.48, 0.25 to 0.85; 0.56, 0.32 to 0.9), whereas midterm DAPT showed no significant difference (OR 0.62, 0.33 to 1.06). Furthermore, short-term DAPT followed by P2Y12 inhibitor or aspirin monotherapy had no remarkable difference compared to short-term DAPT followed by aspirin monotherapy (OR 0.90, 0.54 to 1.5). According to the accumulative rankings by SUCRA, we found that the possible best treatment improving primary endpoint was 3-month DAPT, while the effect is consistent with midterm and standard term DAPT. In addition, in the analyses of the primary endpoint, the worst treatment was extended-term DAPT.
Secondary outcomes
All-cause mortality was similar in extended-term DAPT, 12-month DAPT, mid-term DAPT or short-term DAPT. No noticeable difference was also shown for cardiac mortality. Compared with 12-month DAPT, extended-term DAPT, mid-term DAPT and short-term DAPT showed no significant differences in the matter of MI or in respect of stroke. In terms of definite or probable stent thrombosis, compared with 12-month DAPT, extended-term DAPT, mid-term DAPT and short-term DAPT showed no significant differences. Similar result was also shown on the subject of TVR. There were no significant differences with respect to major bleeding between the different DAPT strategies.
Rank probabilities
Figures 4 and Figure 5 show the ranking probabilities for all treatments included (with detail ranking results for other outcomes summarized in Additional file 10 and 11). For the treatment effect of ameliorating primary endpoint, short-term DAPT and standard-term DAPT ranked first with the highest probability (72.18% and 63.55%, respectively), while midterm and extended-term DAPT ranked last with the highest probability (62.84% and 95.32%, respectively). For the effect of reducing all-cause mortality, midterm DAPT ranked first with the highest probability (37.59%), while the extended-term DAPT had the highest probability of ranking last in the incidence of more all-cause mortality (53.43%). The short-term DAPT had the highest probability of ranking first in the incidence of less cardiac mortality and MI (42.98% and 64.05%), while the midterm DAPT had the highest probability of ranking last in the incidence of more cardiac mortality and MI (52.57% and 54.27%, respectively). According to the analysis of stroke and TVR, midterm DAPT (76.61%) and standard-term (44.92%) were the treatments with the highest probability of achieving a good prognosis. In contrast, the treatments with the lowest probability were short-term and midterm DAPT, with a probability of 46.15% and 43.52%, respectively. For the effect of delaying the progression of definite or probable stent thrombosis, short-term DAPT was the most appropriate treatment strategy for ranking first with the highest probability (52.67%), while midterm ranked last with the highest probability (81.18%). To postpone the event of major bleeding, midterm DAPT was favorable treatment for diabetes (59.08%), while extend-term DAPT achieved the worst outcome (89.32%).