Cost-effectiveness analysis
post-thrombotic syndrome, VTE, PTS
ACUTE DVT, EVENTS, SECONDARY, SEQUELA
Two health economic analyses will be conducted. The main analyses will be performed from the perspective of the NHS and personal social services, with secondary analyses from a societal perspective.A within-trial analysis will compare GCS to no thromboprophylaxis over the 90 days of the study. Resource use items associated with treatments in hospital and community care will be collected using case notes and self-completed patient resource use diaries over the 90-day follow-up, and costed using manufacturers’ list prices, previous literature and national reference costs. Days off work and normal activities and other patient-related costs will be collected for a secondary analysis. EQ-5D will be collected at baseline and follow-up, analysed using the NICE approved tariff. Appropriate methods will be used to handle missing data and any relevant subgroups in line with the Statistical analysis plan.If there are clinically relevant and measurable differences in VTE or QoL between the study arms at 90 days, a Markov (state-transition) decision model will be constructed to compare the Incremental Cost-Effectiveness Ratio (ICER) up to 2 years for GCS versus no GCS. The time horizon of the model will be 2 years allowing extrapolation of sequela of VTE events (such as post-thrombotic syndrome (PTS)) over the longer term to quantify the impact of VTE on patient health (quality adjusted life years (QALYs)) and resource use. A preliminary model has been constructed based on published literature to identify the key variables that would need to be collected during the clinical study, and to estimate the number needed to treat (NNT) to avoid one VTE, above which GCS would not be considered cost-effective at NICE thresholds. The 2-year time point was chosen as we know from previous research that the incidence of PTS after acute DVT levels out after the first year.This preliminary model conservatively assumes 30% of patients with VTE develop PTS, with 3% of those patients having severe PTS. The cost of purchasing and applying GCS stockings is approximately £22.46.The health economic analyses will be conducted and reported according to NICE reference case and Consolidated Health Economic Evaluation Reporting Standards (CHEERS) guidelines,