Patient and Hospital Characteristics

Patient characteristics were extracted including demographics and comorbid disease with a focus on risk factors previously associated with device explantation⁵ as defined in Appendix 2. Charlson comorbidity index (CCI) for each subject was calculated using the standard components¹¹.

The type of intravenous (IV) antibiotic(s) administered was determined using Healthcare Common Procedure Coding System (HCPCS) codes billed in conjunction with the index CPT code, shown in Appendix 3. Perioperative antibiotic regimen was considered to be consistent with AUA guidelines if it included an aminoglycoside or aztreonam plus vancomycin or a first or second generation cephalosporin, or a penicillin with beta-lactamase inhibitor⁶. The type of outpatient antibiotic prescribed was determined from outpatient prescription claims within one week of index procedure, and duration determined as the number of days indicated on outpatient prescription claim.

The primary endpoint was device explantation within 90 days of device placement, as defined by CPT codes (Appendix 1). We included any code that specifies device removal or device removal and replacement through an infected field. We did not include codes for device repair or device removal and replacement, assuming that these codes would be more likely to correspond to device failure or pain rather than an infectious complication. The 90-day endpoint was chosen to coincide with the global period for these procedures and in an effort to capture early infectious complications, which are intuitively more likely to be impacted by the choice of peri- and post-operative antibiotic selection than complications requiring explantation remote from implantation¹².