Epidemiology and Diagnosis of Post-Thrombotic Syndrome: Qualitative Synthesis with a Systematic Review.

: Post-thrombotic syndrome (PTS) is a common and debilitating sequela of lower limb deep vein thrombosis (DVT). There is significant heterogeneity in reported PTS incidence due to lack of standardised diagnostic criteria. This review aimed to develop diagnostic criteria for PTS and subsequently refine the reported incidence and severity. : PRISMA principles were followed; however, the review was not registered. The Cochrane CENTRAL database, MEDLINE, Embase, the NHS NICE Healthcare Databases Advanced Search interface, and trial registers including isrctn.com and clinicaltrials.gov were searched for studies addressing areas of interest (PTS definition, epidemiology, assessment). An experienced Clinical Librarian undertook the systematic searches, and two independent reviewers agreed on the relevance of the papers. Conflicts were resolved through panel review. Evidence quality was assessed using a modified Coleman scoring system and weighted according to their relevance to the aforementioned areas of interest. : A total of 339 abstracts were retrieved. A total of 33 full-text papers were included in this review. Following qualitative analysis, four criteria were proposed to define PTS: (1) a proven thrombotic event on radiological assessment; (2) a minimum 24-month follow-up period after an index DVT; (3) assessment with a validated score; and (4) evidence of progression of venous insufficiency from baseline. Four papers conformed to our PTS definition criteria, and the incidence of mild to moderate PTS ranged from 7 to 36%. On reviewing the studies which utilised the recommended Villalta scale, PTS incidence narrowed further to 23-36%. Incidence and severity reached a plateau at 24 months. : Four diagnostic criteria were developed from qualitative synthesis. When these criteria were applied to the literature, the range of reported PTS incidence narrowed. These four criteria may standardise PTS diagnosis in future studies, facilitating the pooling of data for meta-analysis and synthesis of higher levels of evidence.