Kidney donation may raise risk of scrotal surgery later in life

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

\* Donors \* Inclusion criteria: \- Male persons who received a laparoscopic nephrectomy in Ontario, Canada between April 1, 2002, and March 31, 2023 are eligible to enter the study. Exclusion criteria: * Any person with data errors in their database records (such as missing or invalid age; they expect to exclude very few persons for these reasons). Data errors also include evidence of prior dialysis or a prior solid organ transplant, as such persons are not eligible to become a donor. * Any person who was not a permanent Ontario resident (i.e., they live outside of Ontario, and only came to Ontario to donate a kidney to their intended recipient). This will include anyone who is not eligible for the Ontario Health Insurance Plan, anyone whose date of last contact in the databases is less than 4 months after the cohort entry date, and any person without a physician visit in the last 1-year. * Any person who is \<18 years of age on the date of nephrectomy (as only under exceptional circumstances should a person less than 18 be approved for living donation). * Any person who, before donation, received a scrotal ultrasound or a scrotal procedure other than a vasectomy. * Non-donors \* Inclusion, exclusion and selection criteria: * Before nephrectomy, living donors undergo rigorous health screening. The investigators will select a similarly healthy segment of the general population using restriction and matching. * The investigators will randomly assign a cohort-entry date (simulated nephrectomy date) to all male persons who were citizens in Ontario, according to the distribution of cohort-entry dates among donors (April 1, 2002, to March 31, 2023). * Excluded is any person with data errors in their database records (such as missing or invalid age); any person who was not a permanent Ontario resident. This will include anyone who is not eligible for the Ontario Health Insurance Plan, and anyone whose date of last contact in the databases is less than 4 months after the cohort entry date; any person who is \<18 years of age on the cohort entry date * The investigators will then identify baseline illnesses and measures of healthcare access from historic records preceding the cohort entry date. They will then restrict the sample of eligible nondonors to persons without a recorded medical condition that could preclude donation. Such recorded medical conditions will include a hospitalization for mental illness in the prior year; an intensive care unit admission in the prior year; a hospitalization for palliative care services in the prior year; multiple hospital admissions in the prior year; high comorbidity (as assessed by the Charlson comorbidity index and adjusted clinical group scores); receipt of home oxygen therapy; residence at a long-term care facility; dementia; any record of prior nephrology consultation or kidney disease (including receipt of dialysis, a kidney biopsy, or a kidney procedure such as a partial or complete nephrectomy); previous solid organ transplant; disorders of the kidneys, ureters, or bladder; any record of cardiovascular disease (congestive heart failure, cardiovascular procedures, myocardial infarction, peripheral vascular disease, abdominal aortic aneurysm repair, ischemic stroke); hypertension in individuals \<50 years of age (persons with this condition are not accepted as donors in Ontario); any record of obstructive sleep apnea; any cancer diagnosis; any liver disease or cirrhosis; diabetes; any serious infection (hepatitis, HIV, infective endocarditis); any record of autoimmune rheumatic conditions (such as rheumatoid arthritis or systemic lupus erythematosus); and any record of alcoholism. * The investigators will then exclude any person who, before cohort entry, received a scrotal ultrasound or a scrotal procedure other than a vasectomy. * To ensure the nondonors have the same opportunity as donors to obtain health care services from physicians, they will exclude nondonors who had no evidence of a family physician visit in the 2 years prior to index. They will also exclude nondonors with more than 4 family physician visits in the 2 years prior to index, as this could suggest they have an active health issue that needs attention before they would proceed to donate. * Matching \* The investigators will then match each donor to 10 eligible nondonors based on baseline characteristics that might be associated with the risk of scrotal surgery, specifically the age at the time of cohort entry (± 1 years), since amongst adults, as men age they are more likely to have hydroceles; the cohort entry date (± 3 years), to account for any era effects; urban or rural residence (population ≥ 10,000 or \< 10,000), as a rural residence is associated with less access to care and worse outcomes; income (categorized into fifths of average neighborhood income), since lower income is associated with less access to care and worse outcomes; a prior history of vasectomy, and a prior history of inguinal hernia repair, as each procedure on occasion leads to chronic testicular pain. Each nondonor can only be selected once.