Publications of the Week, April 3

Rivaroxaban vs ASA in extended treatment of VTE

Rivaroxaban, even in a prophylactic dose, is more effective in preventing recurrent venous thromboembolism than acetylsalicylic acid (ASA).

In over 3000 patients who underwent 6 to 12 months of anticoagulation therapy for venous thromboembolism, clinicians were not clear about the further course of action: ASA 100 mg per day or once-daily rivaroxaban in either low (10 mg) or higher daily dose (20 mg). Symptomatic recurrent thromboembolism occurred in 1.5% of patients on the higher dose of rivaroxaban, 1.2% of patients on the lower dose, and 4.4% of patients on ASA. Major bleeding occurred in 0.5%, 0.4%, and 0.3% of patients, respectively. Nonmajor bleeding rates in the same groups were 2.7%, 2.0%, and 1.8%.

In the discussion, the authors reminded the readers that in the previous studies ASA reduced the risk of venous thromboembolism recurrence by about a third, and 20 mg of rivaroxaban reduced it by more than two-thirds. The decision to treat or not to treat as well as the choice of treatment may depend on nature of the original event (pulmonary embolism vs deep vein thrombosis), its provoked or unprovoked status, and the presence (or absence) of ongoing risk factors.

Therapies for low back pain: new evidence and medications

Among different pharmacologic therapies for back pain, acetaminophen (INN paracetamol) is likely ineffective, nonsteroidal anti-inflammatory drugs (NSAIDs) have modest effects, while muscle relaxants (acute pain) and duloxetine (chronic pain) have some benefits.

This review, performed at the request of the American College of Physicians, examined the effects of different classes of drugs on acute and chronic back pain. The authors provided their criteria for small, moderate, and large improvements: for a scale from 0 to 100 points, amounting to 5 to 10, 10 to 20, and >20 points, respectively; for a scale measuring the effect in standard deviation units (standardized mean difference [SMD]), 0.2 to 0.5, 0.5 to 0.8, and >0.8 SMD.

For patients with acute back pain, the authors observed no clear benefit of regular acetaminophen use (currently recommended as the first-line treatment) and a small effect of NSAIDs (an average effect of about 8 points on a 100-point scale). The probability of substantial acute pain relief was almost double with the use of muscle relaxants against placebo. There was no convincing evidence supporting the use of benzodiazepines or systemic glucocorticosteroids, and no evidence concerning the use of antiseizure medications.

Examining the effects of different medications on pain intensity in patients with chronic back pain, the authors found no evidence to support the use of acetaminophen, and found evidence suggesting lack of benefits of tricyclic antidepressants and selective serotonin reuptake inhibitors. The effects of NSAIDs in patients with chronic pain were moderate (12 points on a 100-point scale). Opioids, used during short-term trials in such patients, had a small to moderate effect; similar results were observed with tramadol. The beneficial effects of duloxetine were described as small. The authors were not able to detect benefits of muscle relaxants and were unable to estimate the possible benefits of gabapentin/pregabalin.

TAVR vs surgery in intermediate-risk patients with aortic stenosis

Transcatheter aortic-valve replacement (TAVR) is an alternative to surgery in patients with severe aortic stenosis at moderate surgical risk.

Over 1500 patients of an average age of over 79 years with severe aortic stenosis (valve area ≤1 cm² or <0.6 cm²/m² of body-surface area and a mean gradient >40 mm Hg) participated in this randomized controlled trial comparing TAVR with surgery. The patients were judged to be at intermediate surgical risk (3% to 15% 30-day surgical mortality).

The probability of death or disabling stroke within 24 months of surgery was 12.6% in the TAVR and 14.0% in the surgical group. Acute kidney injury (1.7% vs 4.4%) and atrial fibrillation (12.9% vs 43.4%) were less common among TAVR patients; however, this group had a larger need for pacemaker implantation (26% vs 6.6%) and a higher rate of major vascular complications.