Background Philadelphia (Ph) chromosome-negative myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematopoietic stem cell clonal diseases. Most patients with MPN are asymptomatic at diagnosis although some of them suffer from constitutional symptoms. Thrombosis and bleeding can also be one of the initial manifestations although the reported prevalence varied considerably across the studies. This systematic review and meta-analysis was conducted with the aims to better understand the prevalence and characteristics of thrombosis and bleeding among patients with newly-diagnosed MPN. Methods Using a search strategy that included the terms for myeloproliferative neoplasms, thrombosis, and bleeding, two investigators independently searched for published articles indexed in the MEDLINE and EMBASE databases from inception to August 2018. The pooled prevalence was calculated using the DerSimonian–Laird random-effects model with a double arcsine transformation. Results A total of 29 cohort studies (8 prospective and 21 retrospective) with 13,436 patients with MPN were included into this meta-analysis. At diagnosis, the pooled prevalence of overall thrombosis among patients with MPN was 20.0% (95% CI, 16.6–23.8%; I 2 96%), with the pooled prevalence of arterial thrombosis of 16.2% (95% CI, 13.0–20.0%; I 2 95%) and the pooled prevalence of venous thrombosis of 6.2% (95% CI, 4.9–7.8%; I 2 89%). Common thrombotic events included cerebrovascular disease/transient ischemic attack, coronary heart disease, and deep venous thrombosis. The pooled prevalence of hemorrhagic complications among patients who were newly diagnosed with MPN patients was 6.2% (95% CI, 5.0–7.8%; I 2 85%). Common sites of bleeding included gastrointestinal, mucosal, and cutaneous bleeding. Conclusions Thrombosis and bleeding are common initial manifestations of MPN. Investigations for MPN should be considered for patients who present with unexplained thrombosis or abnormal bleeding. Electronic supplementary material The online version of this article (10.1186/s12885-019-5387-9) contains supplementary material, which is available to authorized users.

The current systematic review and meta-analysis aimed to summarize the results of all available studies to compare the efficacies of rituximab and conventional treatment for acquired thrombotic thrombocytopenic purpura (TTP). Three investigators independently searched studies in the MEDLINE and EMBASE databases published before December 11, 2018. To be included in the meta-analysis, studies needed to be randomized-controlled or cohort studies comparing the efficacies of rituximab and conventional therapy for TTP treatment. The effect estimates and 95% confidence intervals (CIs) from each study were collected, and Mantel-Haenszel methods were used to pool the data. A total of 570 patients from 9 eligible studies were included in the meta-analysis (280 patients in the rituximab arm and 290 in the conventional treatment arm). Patients receiving rituximab in an acute phase to induce disease remission had a significantly lower relapse rate than those given conventional treatment (odds ratio [OR]: 0.40, 95% CI: 0.19-0.85, P = .02, I 2 = 43%). Similarly, the relapse rate in the rituximab group for preemptive therapy to prevent clinical relapse was also significantly lower than in the control group (OR: 0.09, 95% CI: 0.04-0.24, P < .00001, I 2 = 11%). Furthermore, the conventional treatment group had a significantly higher mortality rate than the rituximab group during the follow-up (OR: 0.41, 95% CI: 0.18-0.91, P = .03, I 2 = 0%). Rituximab offered high efficacy for the prevention of relapses and lower mortality rate in cases of acquired TTP.

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