\*Donors\*
Inclusion Criteria: Living kidney donors who underwent donor nephrectomy in Ontario, Alberta, and British Columbia, Canada, between July 1, 1992, and March 31, 2024 are eligible to enter the study.
Exclusion Criteria:
* Any person with data errors in their database records (such as missing or invalid age; it is expected to exclude very few persons for these reasons). Data errors also include evidence of prior dialysis or a prior solid organ transplant, as such individuals are not eligible to become donors.
* Any person who was not a permanent resident of the province (i.e., the patient lives outside of the province, and only came to the province to donate a kidney to the intended recipient). This will include anyone who is not eligible for the province's health insurance plan, anyone whose last contact date in the databases is less than 1 year after the cohort entry date, and anyone without a physician visit in the year following the nephrectomy hospital discharge.
* 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 with a history of kidney stones.
\*Non-donors\*
Inclusion criteria: Before nephrectomy, living donors undergo rigorous health screening. A similarly healthy segment of the general population will be selected using restriction and matching. A random cohort entry date (simulated nephrectomy date) will be assigned to all persons who were residents of the province, according to the distribution of cohort entry dates among donors (July 1, 1992, to March 31, 2024).
Exclusion Criteria:
* Any person with data errors in their database records (such as missing or invalid age).
* Any person who was not a permanent resident of the province. This will include anyone who is not eligible for the province's health insurance plan and anyone whose last contact date in the databases is less than 1 year after the cohort entry date.
* Any person who is \<18 years of age on the cohort entry date.
* Anyone who is pregnant at the time of the cohort entry date.
* Baseline illnesses and measures of health care access from historic records preceding the cohort entry date will be identified. The sample of eligible nondonors will be restricted 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, where data are available); 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 Canada); 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.
* To ensure the nondonors have access to health care services from physicians, nondonors who had no evidence of a family physician visit in the 2 years prior to cohort entry will be excluded. Additionally, nondonors with more than 5 family physician visits in the 2 years prior to cohort entry will be excluded, as this could suggest an active health issue that needs attention before donation could occur.
* Any person with a history of kidney stones.
