MONDAY, May 15, 2017 (HealthDay News) — Long-term quinine exposure is associated with increased mortality, according to a research letter published in the May 9 issue of the Journal of the American Medical Association.

Laurence Fardet, M.D., Ph.D., from the Université Paris Est Créteil, and colleagues used data from The Health Improvement Network (a primary care database with information on more than 12 million individuals in the United Kingdom) to examine the correlation between long-term quinine exposure and all-cause mortality. Adults who received incident quinine salt prescriptions (mean dosage, 100 mg/d) for idiopathic muscle cramps or restless leg syndrome for at least one year were considered exposed. They compared all-cause mortality for exposed and unexposed populations in models adjusted for sociodemographic data, underlying conditions, and concomitant prescriptions.

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Exposed individuals received a median of 203 mg/d of quinine. The researchers found that there were 11,598 deaths among the 44,699 exposed individuals and 26,753 among the 130,496 unexposed individuals (4.2 versus 3.2 per 100 person-years; adjusted hazard ratio, 1.24). Regardless of the indication for prescription, the increase in risk of death was stronger among those younger than 50 years (adjusted hazard ratio, 3.06). There was a dose effect, with adjusted hazard ratios of 1.25, 1.83, and 2.24 for exposure of 200 to 299 mg/d, 300 to 399 mg/d, and 400 mg/d or more versus less than 200 mg/d.

“The benefits of quinine in reducing cramps should be balanced against the risks,” the authors write.

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