Validation of venous thromboembolism diagnoses in patients receiving rivaroxaban or warfarin in The Health Improvement Network

Abstract

PurposeTo describe the effect that validation of venous thromboembolism (VTE) coded entries in the health improvement network (THIN) has on incidence rates of VTE among a cohort of rivaroxaban/warfarin users.MethodsAmong 36 701 individuals with a first prescription for rivaroxaban/warfarin between 2012 and 2015, we performed a two‐step VTE case identification process followed by a two‐step case validation process involving manual review of patient records. A valid case required a coded entry for VTE at some point after their first rivaroxaban/warfarin prescription with evidence of referral/hospitalization either as a coded entry or entered as free text. Positive predictive values (PPVs) with 95% confidence intervals (CIs) were calculated using validated cases as the gold standard. Incidence rates were calculated per 1000 person‐years with 95% CIs.ResultsWe identified 2166 patients with a coded entry of VTE after their initial rivaroxaban/warfarin prescription; incidence rate of 45.31 per 1000 person‐years (95% CI: 43.49‐47.22). After manual review of patient records including the free text, there were 712 incident VTE cases; incidence rate of 14.90 per 1000 person‐years (95% CI: 13.85‐16.02). The PPV for coded entries of VTE alone was 32.9%, and the PPV for coded entries of VTE with a coded entry of referral/hospitalization was 39.8%; this increased to 69.6% after manual review of coded clinical entries in patient records.ConclusionsAmong rivaroxaban/warfarin users in THIN, valid VTE case identification requires manual review of patient records including the free text to prevent outcome misclassification and substantial overestimation of VTE incidence rates.

Venous Thromboembolism Among People With HIV: Design, Implementation, and Findings of a Centralized Adjudication System in Clinical Care Sites Across the United States

“…Several general population studies have identified issues with relying solely on medical diagnoses including inaccuracy, missed events, and low PPV. 59,60 We found diagnoses misidentified potential VTEs when the documentation was referencing VTE prophylaxis not VTE. Diagnoses also were sometimes inaccurate in the setting of superficial phlebitis.…”

Safety profile of rivaroxaban in first-time users treated for venous thromboembolism (deep vein thrombosis and pulmonary embolism) in four European countries

“…The de nitions of outcomes were based on speci c diagnostic procedure codes (Read Codes in the UK, or International Statistical Classi cation of Diseases and Related Health Problems [ICD] 9th Revision or ICD 10th Revision in Germany, the Netherlands and Sweden) and were harmonized between databases as much as possible for the purpose of this analysis; studies that detail the design and validation of this methodology have previously been published [10,16]. The evaluated safety outcomes included bleeding events that led to hospitalization (as measure of severity), categorized as intracranial haemorrhage (intracerebral haemorrhage, subarachnoid haemorrhage or subdural haematoma), gastrointestinal bleeding (upper and lower gastrointestinal tract), urogenital bleeding and bleeding events at other sites [17]. All-cause mortality was also evaluated among rivaroxaban users.…”

Safety profile of rivaroxaban in first-time users treated for venous thromboembolism in four European countries

“…The definitions of outcomes were based on specific diagnostic procedure codes (Read Codes in the UK, or International Statistical Classification of Diseases and Related Health Problems [ICD] 9th Revision or ICD 10th Revision in Germany, the Netherlands and Sweden) and were harmonized between databases as much as possible for the purpose of this analysis; studies that detail the design and validation of this methodology have previously been published [ 10 , 16 ]. The evaluated safety outcomes included bleeding events that led to hospitalization (as measure of severity), categorized as intracranial haemorrhage (intracerebral haemorrhage, subarachnoid haemorrhage or subdural haematoma), gastrointestinal bleeding (upper and lower gastrointestinal tract), urogenital bleeding and bleeding events at other sites [ 17 ]. All-cause mortality was also evaluated among rivaroxaban users.…”