A study of clinical complications and risk factors in 1,001 native and transplant kidney biopsies in Sweden.

BACKGROUND: In Sweden, native and transplant kidney biopsies are usually performed in major renal medical centers. PURPOSE: To clarify risk factors in native and transplant kidney biopsies to improve patient safety. MATERIAL AND METHODS: A total of 1001 biopsies (in 352 women and 565 men) were included. The median age was 54 years (range, 16-90 years). Data were derived from 826 native kidney biopsies (640 prospective and 186 retrospective) and 175 transplant kidney biopsies (170 prospective and 5 retrospective). Various factors and complications were registered while performing native and transplant kidney biopsies, focusing on major (e.g. blood transfusions, invasive procedures) and minor complications. The prospective protocol was used at six centers and at one center data were obtained retrospectively. RESULTS: Women were at greater risk of overall complications than men (12.2% vs. 6.5%; P = 0.003; odds ratio [OR], 2.0; confidence interval [CI], 1.3-3.1) as well as of major complications (9.6% vs. 4.5%; P = 0.002; OR, 2.2, CI 1.3-3.7). Major complications occurred more commonly after biopsies from the right kidney, in women than in men (10.8% vs. 3.1%; P = 0.005; OR, 3.7; CI, 1.5-9.5), and in patients with lower BMI (25.5 vs. 27.3, P = 0.016) and of younger age (45 years vs. 52.5 years; P = 0.001). Lower mean arterial pressure in transplant kidney biopsies indicated a risk of major complications (90 mmHg vs. 98 mmHg; P = 0.039). Factors such as needle size, number of passes, serum creatinine, and eGFR did not influence complication rates. CONCLUSION: The present findings motivate greater attention being paid to the risk of major side-effects after right-side biopsies from women's kidneys, as well as after biopsies from younger patients and patients with lower BMI.