Objective To investigate the seasonal variability of the onset of acute deep vein thrombosis(DVT).Methods The clinical manifestations in 774 DVT patients during January 2008 to December 2012 were collected and circular distribution statistics was used to identify seasonal variability.Results The total sample had the significant seasonal variability (P ＜ 0.01):DVT was most frequent in winter while less frequent in summer and the peak day was January 1.Female subgroup has significant seasonal variability (P ＜0.01):on peak in winter and at trough in summer while male subgroup has no significant seasonal variability (P ＜ 0.01).Different age subgroups (＜ 40 years,40-69 years,＜70 years)have significant seasonal variability(P ＜ 0.05,P ＜ 0.01,P ＜ 0.01).DVT was most common in December and less frequent in August.Left lower limb subgroup and both lower limb subgroup has significant seasonal variability (P ＜ 0.01,P ＜ 0.01),on peak in December-January.Immobilization subgroup also has significant seasonal variability (P ＜ 0.001):frequent in winter,January 1 is on the peak.Conclusions DVT has significant seasonal variability in onset:it is most frequently seen in winter while less frequent in summer.Some subgroups (female,＜70 years and immobilization) have the most significant seasonal variability in onset.

Objective To compare the clinical efficacy of catheter directed thrombolysis(CDT ) ,thrombectomy(ST ) and system‐atic anticoagulant(SA) in treating acute iliofemoral deep vein thrombosis(AIFDVT ) of lower limb using Meta analysis method . Methods The systematic review was initialted by electronic literature searches (PUBMED ,MEDLINE ,ELSEVIER ,etc .) for stud‐ies comparing catheter directed thrombolysis ,thrombectomy and systematic anticoagulant clinical effects published from January 1984 to January 2014 based on the keyword such as iliofemoral deep vein thrombosis;thrombolysis;anticoagulant therapy ;throm‐bectomy ;RCTs;Meta analysis.A Meta analysis was conducted to estimate early vein patency ,post thrombotic syndrome(PTS) , venous reflux(VR) rate ,venous obstruction(VO) rate ,etc .Results Ten RCTs were included in this analysis ,including 626 pa‐tients .The early vein patency rate was higher in the CDT group and the difference was statistically significant(OR=4 .61 ,95% CI 1 .93-10 .98 ,P<0 .05);there was no statistically difference between ST and SA group(OR= 2 .54 ,95% CI 0 .49 -13 .24 ,P>0 .05) .The post thrombotic syndrome rate was less both in the CDT group(OR=0 .18 ,95% CI 0 .07 -0 .43 ,P< 0 .05) and ST group(OR=0 .50 ,95% CI 0 .28 -0 .87 ,P< 0 .05);the difference was statistically significant .The difference of the venous reflux rate was not statistically significant in both two groups .The venous obstruction rate was less in the CDT group(OR=0 .19 ,95% CI 0 .11-0 .34 ,P<0 .05) and the difference was statistically significant ;while the difference was not statistically significant between ST and SA group (OR=1 .53 ,95% CI 0 .72-3 .26 ,P>0 .05) .Conclusion For acute iliofemoral deep vein thrombosis(AIFDVT) , short term (< 7 d) outcomes of catheter directed thrombolysis was better than anticoagulant therapy ,but thrombolysis brought more bleeding .In long term(>6 m) outcomes ,the post thrombotic syndrome rate was less both in the thrombolysis group and the thrombectomy ,and catheter directed thrombolysis could diminish the vein obstruction rate .