Objectives To investigate whether additional catheter-directed thrombolysis (CDT) improves long-term quality of life (QOL) compared with standard treatment with anticoagulation and compression stockings alone in patients with proximal deep vein thrombosis (DVT).

Design Open-label randomised controlled trial.

Setting 19 Hospitals in the Norwegian southeastern health region.

Participants Patients (18–75 years) with a high proximal DVT, symptoms <21 days and no increased risk of bleeding were eligible. 189 of 209 recruited patients completed 24 months of follow-up.

Interventions Participants were randomised to additional CDT with alteplase for 1–4 days or to standard treatment only with 6 months of anticoagulation and 24 months of compression stockings.

Primary and secondary outcome measures Planned secondary outcome measures included QOL as assessed with the generic instrument EQ-5D and the disease-specific instrument VEINES-QOL/Sym. Primary outcome measure was post-thrombotic syndrome (PTS) after 24 months.

Results After 24 months there were no differences in QOL between the additional CDT and standard treatment arms; mean difference for the EQ-5D index was 0.04 (95% CI −0.10 to 0.17), for the VEINES-QOL score 0.2 (95% CI −2.8 to 3.0) and for the VEINES-Sym score 0.5 (95% CI −2.4 to 3.4; p values>0.37). Independent of treatment arms, patients with PTS had poorer outcomes than patient without PTS; mean difference for EQ-5D was 0.09 (95% CI 0.03 to 0.15), for VEINES-QOL score 8.6 (95% CI 5.9 to 11.2) and for VEINES-Sym score 9.8 (95% CI 7.3 to 12.3; p values<0.001).

Conclusions QOL did not differ between patients treated with additional CDT compared with standard treatment alone. Patients who developed PTS reported poorer QOL and more symptoms than patients without PTS. QOL should be included as an outcome measure in clinical studies on patients at risk of PTS.

Trial registration NCT00251771