Thakrar 2024: buprenorphine-precipitated withdrawal in hospital patients

What they tested

Researchers reviewed records at three academic hospitals in Philadelphia for adults with opioid use disorder who began buprenorphine between January 2020 and December 2021, with a first dose of at least 2 mg under the tongue after a Clinical Opiate Withdrawal Scale (COWS) score of 8 or more. People started on low-dose regimens, or without a withdrawal score recorded within 4 hours, were left out.

Precipitated withdrawal, a sudden worsening of withdrawal caused by the medicine, was defined as a rise of 5 or more COWS points from just before to within 4 hours after the first dose. Four possible risk factors were examined: withdrawal severity beforehand, first dose, body mass index (BMI) and urine fentanyl level.

What they found

Overall, 26 of 226 patients (11.5%) met the definition. Among them, the median rise in COWS score was 9 points.

Of 123 patients with confirmed fentanyl use, 20 (16.3%) had precipitated withdrawal.

A BMI of 30 or more, compared with under 25, was linked to higher odds (adjusted odds ratio 5.12, 95% CI 1.31-19.92). So was a urine fentanyl level of 200 ng/mL or more, compared with under 20 ng/mL (adjusted odds ratio 8.37, 95% CI 1.60-43.89). Both confidence intervals were wide.

Limits

• It was a look back at records from three hospitals in one city.
• People without a withdrawal score recorded within 4 hours were excluded, which could shift the rate either way.
• The risk-factor estimates were imprecise, and the authors say the rate, and whether fentanyl built up in the body is a risk factor, need confirming.

What it means if you're considering naltrexone

Estimates of how often buprenorphine causes precipitated withdrawal vary between studies: this one found 11.5% in hospital patients, while a large emergency department trial (D'Onofrio 2023) found under 1%. The study concerns buprenorphine only. Naltrexone's own precipitated withdrawal risk is covered in the site's precipitated withdrawal guide.