Participants will be defined as having ATR if they receive a diagnosis for ATR as well as one of the following procedures: tenotomy or primary ruptured Achilles Tendon (AT) repair (with or without graft) within 7 days of diagnosis. Index will be based on the earlier date of diagnosis or procedure. Participants with ATR, and exposures to Fluoroquinolone (FQ) or any of the other antibiotics or febrile illness not treated with antibiotic, within a defined study period and at least 1 year of continuous enrollment prior to the event will be included. It will use data from 3 databases, which are Truven CCAE and Medicare (Supplemental) and Optum ClinFormatics (Optum).

Participants will be defined as having a RD if they received a diagnosis of RD and a procedure for RD, e.g.: sclera buckle, vitrectomy, retinopexy, retinal cryotherapy, silicone oil fill, air gas fluid exchange or pneumatic retinopexy, within 14 days of index. Index will be defined as the earlier date of diagnosis or procedure. Participants with RD, and exposures to FQ or any of the other antibiotics or febrile illness not treated with antibiotic, within a defined study period and at least 1 year of continuous enrollment prior to the event will be included. It will use data from 3 databases, which are Truven CCAE and Medicare (Supplemental) and Optum ClinFormatics (Optum).

Participants will be defined as having AAD if they received a primary diagnosis for aortic aneurysm, aortic rupture or dissection and have also received an aortic repair surgical procedure concurrently to the AAD diagnosis, in an inpatient or emergency department (ED) setting. Index will be defined as the earlier date of diagnosis or procedure. Participants with AAD, and exposures to FQ or any of the other antibiotics or febrile illness not treated with antibiotic, within a defined study period and at least 1 year of continuous enrollment prior to the event will be included. It will use data from 3 databases, which are Truven CCAE and Medicare (Supplemental) and Optum ClinFormatics (Optum).

Participants will not receive any intervention as a part of this study. The FQ include all oral forms of FQ (24-hours extended release tablets, extended release tablets, oral solution, oral suspension, oral tablet, pack). The drugs included are ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin.

Participants will be having ATR if they receive a diagnosis for ATR and 1 of the following: tenotomy/primary ruptured AT repair (with/without graft) within 7 days of diagnosis. Participants will be having RD if they receive a diagnosis of RD and a procedure for RD, e.g.: sclera buckle, vitrectomy, retinopexy, retinal cryotherapy, silicone oil fill, air gas fluid exchange or pneumatic retinopexy, within 14 days of index (earlier date of diagnosis/procedure). Participants will be having AAD if they receive a diagnosis for aortic aneurysm, aortic rupture/dissection and an aortic repair surgical procedure concurrently to it, in an inpatient/ED setting. The FQ include all oral forms of FQ (ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin). Relative risk of RD, ATR, and AAD between periods of exposure and non-exposure to FQ will be assessed using number of events. Temporal associations between RD, ATR or AAD and exposure to FQ will be estimated.

Other antibiotics includes amoxicillin, azithromycin, trimethoprim and trimethroprim/sulfamethoxazole. Relative risk of RD, ATR, and AAD between periods of exposure and non-exposure to other antibiotics will be assessed using number of events. Temporal associations between RD, ATR or AAD and exposure to other antibiotics will be estimated.

Febrile illness not treated with antibiotics is defined as: concurrent diagnoses of viral disease with concurrent fever, and no concurrent prescription for any antibiotic during the 60-day period before and after the first date of viral disease diagnosis; or a diagnosis of influenza with no concurrent inpatient admission during the 60-day period pre- or post-influenza diagnosis, and no prescription for any antibiotics during the 60-day period pre- or post-influenza diagnosis. Relative risk of RD, ATR, and AAD between periods of exposure and non-exposure to febrile illness not treated with antibiotics will be assessed using number of events. Temporal associations between RD, ATR or AAD and febrile illness not treated with antibiotics (analyzed as an exposure) will be estimated.