## 2 Materials and Methods  
The current study was performed with approval from the Center for Population Health Science at Stanford University in the U.S. Patient data collected from the Optum Clinformatics Data Mart Claims Database were derived from commercial and Medicare Advantage health insurance claims. Optum Clinformatics Data Mart is a database comprised of administrative health claims submitted for payment by providers and pharmacies. These claims are verified, adjudicated, adjusted, and de-identified. Data are included for only those covered lives, roughly 70 million over a 14-year period, with both medical and prescription drug coverage. Costs are standardized to create standard prices across all provider services. International Classification of Disease Ninth and Tenth Revisions, Clinical Modification (ICD-9-CM, ICD-10-CM) codes, and Current Procedural Terminology (CPT) codes were used to identify the study cohort, treatments, and comorbidities. A comprehensive list of ICD-9/10 and CPT codes summarizing the analytical steps for the data analysis and inclusion/exclusion criteria are presented in Supplementary File S1. This method has been used in other studies [11; 12; 13; 14], and, given de-identified information, this study was deemed exempt from informed consent requirements by the Stanford University Medical Center Institutional Review Board.  
Patients who had undergone BPH surgery (index date) between 2004 and 2017 in the U.S. were reviewed. As per primary aim, only those patients with an associated code for specific BPH surgical procedure were included (i.e., TURP, HoLEP, ThuLEP, UroLift). Trends and distribution over the years of enrolment were analyzed and reported for each single procedure over the time of database enrolment across the U.S. Moreover, as per inclusion criteria, subjects at least 50 years old, with at least 6 months enrolment time before, and 1 month after the index date were further assessed leading to the final of n = 82,458 men. Additionally, patients were considered eligible per final enrolment, only if they had a least one urodynamic, cystourethroscopy, USG, biopsy, uroflowmetry, or surgical urological procedure treatment code. Overall, this led to the final cohort composition of n = 51,448 men.  
Per the secondary aim of the study, we reviewed the trends in adoption of various diagnostic methods for BPH including urodynamic studies, cystourethroscopy, transrectal ultrasound, prostatic biopsy, uroflowmetry, and the measurement of post-void residual urine volume (PVR). The collected data included patient age, race, household income, educational status, and co-morbidities. In addition, the annual costs of BPH diagnostic and treatment modalities were reviewed from the database for both diagnostic and therapeutic BPH-related procedures. All costs were standardized based on Medicare Relative Value Units and other pricing methods, adjusting for inflation. Finally, incidental diagnoses of prostate cancer (PCa) detected during BPH procedures were recorded over the years to depict the trends in cancer detection and the median prostate specific antigen (PSA) values associated with BPH patients ultimately addressed to surgical disobstruction.