Antibiotic proved to be Achilles’ heel for some

By Lynda Williams, Senior medwireNews Reporter

US clinicians have identified patients at particular risk for Achilles injury while using quinolones.

Data collated from 6.4 million patients participating in The Health Improvement Network (THIN) database showed that individuals were 4.3 times more likely to experience Achilles tendonitis and 2.0 times more likely to experience rupture while using this type of antibiotics than nonusers.

The risk for Achilles tendonitis was highest among patients aged over 60 years (odds ratio [OR]=8.3 vs 1.6 in younger patients), people with a nonobese body mass index (OR=7.7 vs 2.4 among obese patients), and patients who were also using oral glucocorticoids (OR=9.1 vs 3.2 for nonusers).

The researchers also identified a trend toward an increased risk for Achilles tendinopathy while using quinolones among women (OR=5.0 vs 3.6 in men), patients with diabetes (OR=7.0 vs 4.1 for individuals without diabetes), and patients with renal failure or using dialysis (OR=20.0 vs 3.9 for patients with healthy kidneys).

Women using quinolones were also at significantly increased risk for Achilles rupture compared with men (OR=4.0 vs 1.1), with borderline significant risks also found for glucocorticoid users (OR=3.7 vs 1.3), and nonobese patients (OR=2.6 vs 0.5 for obese).

"These patient characteristics should be considered carefully by physicians when making decisions regarding antibiotic choice," write Barton Wise (University of California, Sacramento) and co-authors.

"Greater caution may be needed in considering quinolone use in individuals with a higher-risk profile."

The team determined the OR for Achilles injury associated with antibiotic prescriptions using THIN data from 28,907 patients with Achilles tendonitis and 7685 patients with Achilles rupture for the 30 days before injury.

No other antibiotic use was significantly associated with an increased risk for Achilles tendinopathy.

Wise et al say it is "somewhat unclear" why quinolones are associated with tendon and cartilage damage but believe the effect is "multifactorial and likely includes an ischemic component, degradation of matrix, and toxic effects on the mitochondria and other cell components."

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