Key takeaways:

• About one-third of the variability in biopsy decisions were tied to physician-level differences.
• Strategies are needed to inform best practices and guidelines for treating patients with IgA nephropathy.

Practices for ordering kidney biopsies or prescribing glucocorticoids for patients with immunoglobulin A nephropathy vary among physicians in Canada, according to study data published in Kidney360.

Researchers wrote that understanding variability patterns for physicians treating patients with immunoglobulin A (IgA) nephropathy could help inform treatment strategies and improve adoption of updated Kidney Disease: Improving Global Outcomes guidelines.

About one-third of the variability in biopsy decisions and 7.5% of the differences in glucocorticoid prescription decisions were tied to physician-level differences. Image: Adobe Stock

“Understanding preexisting physician practice patterns is critical for interpreting the uptake of emerging evidence and increasing implementation of updated guidelines,” Bryce Barr, MD, MSc, assistant professor in the division of nephrology at University of Manitoba, Canada, and colleagues wrote.

In a retrospective cohort study, the researchers examined how 38 physicians in Manitoba, Canada, made treatment decisions for 380 adults with biopsy-proven IgA nephropathy (median age at diagnosis, 42 years; 59% men) from 2002 to 2021.

The primary outcomes were the number of days between first nephrology visit and kidney biopsy and the likelihood of glucocorticoid prescription after biopsy, and how these decisions differed among physicians.

Results showed that the median time to kidney biopsy was 63 days. About one-third of the variability in time to kidney biopsy could be traced back to physician-level differences, according to the researchers.

The median time ratio for biopsy decisions was 2.65 (95% CI, 1.99-3.79), indicating that biopsy decisions could take nearly three times longer based on whether a patient was seen by a “slow-to-biopsy” vs. a “quick-to-biopsy” physician, according to the researchers.

Time to biopsy was longer for patients with higher eGFR vs. lower eGFR (time ratio = 1.52; 95% CI, 1.25-1.88). For patients in urban areas, higher proteinuria vs. lower proteinuria was linked to shorter time to biopsy (time ratio = 0.76; 95% CI, 0.59-0.92). Patients residing in rural areas had longer time to biopsy vs. urban areas (time ratio = 1.62; 95% CI, 1.09-2.39) except when they had higher proteinuria vs. patients in rural areas with lower proteinuria (time ratio = 0.48; 95% CI, 0.26-0.86).

In addition, about 7.5% of differences in glucocorticoid prescription decisions could be traced to physician-level differences, according to the researchers.

The median odds ratio for glucocorticoid prescription decisions was 1.59 (95% CI, 1-2.32), showing that prescription decisions could have 59% different odds when seen by a “high-prescribing physician versus a low-prescribing physician,” the researchers wrote.

Odds of receiving a glucocorticoid prescription were greater for patients with higher proteinuria vs. low proteinuria (OR = 1.36; 95% CI, 1.09-1.63) or patients whose biopsy presented crescents (OR = 6.2; 95% CI, 2.12-10.28) or an Oxford T2 lesion (OR = 0.33; 95% CI, 0.02 to 0.64).

Overall, the findings show that key decisions in IgA nephropathy care differed between physicians before the 2021 KDIGO guidelines for management of glomerular diseases, according to the researchers.

Strategies are needed for “targeted knowledge translation” about the best practices for treating patients with IgA nephropathy, the researchers wrote.

“The practice patterns observed in this study pre-date these major shifts in the evidence base, including recognition of long-term risk even at lower levels of proteinuria and the demonstration of treatment effects of immunosuppressive therapies,” Barr and colleagues wrote. “Our findings reinforce how evolving understanding of risk and treatment efficacy must be translated not only into prescribing decisions, but also into upstream diagnostic behaviors.”