Table 4.

Incidence rate ratios for the interaction between tendon rupture and current systemic fluoroquinolone and oral corticosteroid exposure

Tendon rupture	Exposed cases/total	Exposed controls/total	Adjusted IRR	Adjusted p value
Any tendon rupture
Oral corticosteroid alone	287/4836	443/18,356	2.58 (2.19–3.03)	< 0.001
Oral corticosteroid plus fluoroquinolone exposure	36/4836	20/18,356	6.88 (3.93–12.03)	< 0.001
Achilles tendon rupture
Oral corticosteroid alone	148/1557	180/6007	4.59 (3.43–6.14)	< 0.001
Oral corticosteroid plus fluoroquinolone exposure	37/1557	10/6007	19.36 (7.78–48.19)	< 0.001

Adjusted for exact age, body mass index, Charlson co-morbidity score, hypothyroidism, hyperthyroidism, injectable corticosteroid therapy, smoking status, statin therapy and prior history of tendon rupture

IRR incidence rate ratio