Anticoagulation for DVT: Rivaroxaban, Apixaban and the ABCDs of Dose Adjustment

Out of roughly 25 healthcare facilitators sending referrals, only one or two send a report in a structured format. A recent case arrived with mismatched patient names, ages and even genders across different files for what turned out to be the same patient — a PDF here, a broken image file there, no consolidated record. I would rather give no advice than wrong advice built on poorly collated information.

Absolutely, yes — particularly if the D-dimer is done after the acute phase, in a subacute presentation of a few days. Despite the test's high sensitivity, the result can come back in the low hundreds, nowhere near diagnostic. DVT is an anatomical problem, and for an anatomical problem the answer is to see it directly on ultrasound, not infer it from a blood marker. Vascular ultrasound is learnable within three to four months, and we train nearly all our trainees to do it routinely.

Laser ablation for superficial spider veins or one or two perforators has an excellent prognosis, and works well up to the perforator level. But if the saphenofemoral junction itself is regurgitant, open surgery to ligate the SFJ and clip the draining tributaries is usually the better option rather than relying on endovascular ablation alone.

In a fragile patient, angioplasty is best avoided below the knee — it gives reasonable short-term results but nothing very promising long-term. If intervention is genuinely needed, it is more often approached surgically, favouring a reverse femoro-tibial bypass using the patient's own saphenous vein over a prosthetic graft, and favouring open surgery over an endovascular approach in this territory. Below the knee: use the simpler, older, better-proven option, and know when not to intervene at all.

It is a vascular disease, but the vascular problem is not what is causing the pain in this elderly lady — and if medicines can manage the condition, there is no need to intervene, even if that is commercially a loss rather than a win. There has been a silent shift from a doctor-patient relationship to a doctor-hospital relationship, where a patient's data no longer stays with the treating doctor once they change hospitals. Old-school medicine — operating only when needed, never when not needed — is what should endure through that change.

Rivaroxaban, dosed at 15 mg twice daily for an acute presentation.

20 mg once daily. Neither the acute nor the delayed-presentation dose requires renal adjustment, which makes rivaroxaban straightforward to use broadly, including after major orthopaedic surgery such as hip or knee replacement.

Age over 80 years, body weight under 60 kg, and creatinine over 1.5 mg/dL. Meeting these criteria roughly doubles bleeding risk if the standard dose is left unadjusted.

Halve the standard 5 mg twice-daily dose to 2.5 mg twice daily, or move to once-daily dosing in more severe renal impairment or very low body weight.