Four-Month Rifampin Less Costly Than Nine-Month Isoniazid for Latent TB

By Marilynn Larkin

June 16, 2020

NEW YORK (Reuters Health) - A four-month regimen of rifampin - already shown to be as effective against latent tuberculosis as a nine-month course of isoniazid - is also less expensive and requires less health service use, a cost-comparison study finds.

The researchers had also shown previously that a four-month regimen of rifampin had significantly better completion rates and was significantly safer than the usual isoniazid treatment. (https://bit.ly/3hxHUlN)

"However, policymakers do not look only at regimen effectiveness when adopting new regimens, but also consider affordability," Dr. Dick Menzies of McGill University told Reuters Health by email. "For this reason, we decided to look beyond the effectiveness and safety of the regimen and compared the costs...from the perspective of the health system."

Dr. Menzies and colleagues compared costs of four months of rifampin versus nine months of isoniazid using data on all healthcare activities recorded during two randomized clinical trials. Activities were related to initial medical evaluation, study drugs, routine follow-up visits (including assessments of adherence and potential adverse events), and evaluation and management of possible adverse events or active tuberculosis.

Comparisons included high-income (Australia, Canada, Saudi Arabia, and South Korea), middle-income (Brazil and Indonesia), and African countries (Benin, Ghana, and Guinea).

For all sites, the team obtained local unit costs for the five most common tests performed during the study: liver enzymes and bilirubin tests, complete blood count, chest x-ray, tuberculosis microbiological tests, and testing for HIV antibodies

As reported in Annals of Internal Medicine, data from 6,012 adults and 829 children were included in the analysis. The treatment completion rate was 71% among adults and 82% among children. Among adults, 229 adverse events led to treatment discontinuation, 54% of which occurred in high-income countries

Overall, greater health system use and higher costs were seen with nine months of isoniazid compared with four months of rifampin in both adults and children.

The highest costs per participant were in high-income countries: $549.1 in the rifampin group versus $725.4 for isoniazid (mean ratio, 0.76). By contrast, the cost per participant at the African sites was $112.1 for rifampin and $140.5 for isoniazid, and the cost ratio was similar to that in high-income countries (mean, 0.80).

In adults, the cost ratios for the rifampin versus isoniazid regimens were 0.76 in high-income, 0.90 in middle-income, and 0.80 in African countries. Findings were similar in children.

Dr. Menzies said, "Before our study, a common argument was that four months of rifampin would be more costly, since the price of the pills is generally more expensive than isoniazid pills."

"However," he noted, "we found that the higher costs of rifampin pills are offset by reduced health care utilization (e.g., fewer visits and tests) with the shorter regimen - and this was true in low-income countries in Africa, and middle-income countries like Indonesia and Brazil."

"This robust body of evidence of equivalent efficacy, better safety and lower costs supports new recommendations from the World Health Organization to use four months of rifampin as one of the first-line treatments for latent tuberculosis," he added.(https://bit.ly/30KdWVL)

Dr. Aaron Glatt, Chairman, Department of Medicine at South Nassau Communities Hospital and a professor at Icahn School of Medicine at Mt. Sinai in New York City, commented in an email to Reuters Health, "Rifampin is an excellent drug for the treatment of latent tuberculosis, at least as good...as any other currently recommended therapeutic option."

"Shorter-course therapies are, in general, better for compliance, and combination therapies even allow for even shorter regimens," he said. "As the cost appears to also be lower, short-course options are becoming the treatment of choice for latent tuberculosis therapy."

The four-month rifampin regimen should also be compared with 12-week, once-weekly isoniazid and rifapentine, which is included in the US Centers for Disease Control and Prevention's updated recommendations for latent tuberculosis, he noted. (https://bit.ly/3hyptgQ)

SOURCE: https://bit.ly/3fqc8W1 Annals of Internal Medicine, online June 15, 2020.

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